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Gennadiy Murastov, Muhammad Awais Aslam, Tuan-Hoang Tran, Alice Lassnig, [Kenji Watanabe](https://orcid.org/0000-0003-3701-8119), [Takashi Taniguchi](https://orcid.org/0000-0002-1467-3105), Stefan Wurster, Manfred Nachtnebel, Christian Teichert, Evgeniya Sheremet, Raul D. Rodriguez, Aleksandar Matkovic

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[Photoinduced edge-specific nanoparticle decoration of two-dimensional tungsten diselenide nanoribbons](https://mdr.nims.go.jp/datasets/08fc28f4-5cbf-47da-a5a4-811c5df7f461)

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Photoinduced edge-specific nanoparticle decoration of two-dimensional tungsten diselenide nanoribbonsARTICLEPhotoinduced edge-specific nanoparticledecoration of two-dimensional tungsten diselenidenanoribbonsGennadiy Murastov 1✉, Muhammad Awais Aslam1, Tuan-Hoang Tran2, Alice Lassnig3, Kenji Watanabe 4,Takashi Taniguchi 5, Stefan Wurster3, Manfred Nachtnebel6, Christian Teichert1, Evgeniya Sheremet2,Raul D. Rodriguez 2 & Aleksandar Matkovic 1✉Metallic nanoparticles are widely explored for boosting light-matter coupling, optoelectronicresponse, and improving photocatalytic performance of two-dimensional (2D) materials.However, the target area is restricted to either top or bottom of the 2D flakes. Here, weintroduce an approach for edge-specific nanoparticle decoration via light-assisted reductionof silver ions and merging of silver seeds. We observe arrays of the self-limited in size silvernanoparticles along tungsten diselenide WSe2 nanoribbon edges. The density of nano-particles is tunable by adjusting the laser fluence. Scanning electron microscopy, atomic forcemicroscopy, and Raman spectroscopy are used to investigate the size, distribution, andphoto-response of the deposited plasmonic nanoparticles on the quasi-one-dimensionalnanoribbons. We report an on-surface synthesis path for creating mixed-dimensional het-erostructures and heterojunctions with potential applications in opto-electronics, plasmonics,and catalysis, offering improved light matter coupling, optoelectronics response, and pho-tocatalytic performance of 2D materials.https://doi.org/10.1038/s42004-023-00975-6 OPEN1 Chair of Physics, Department Physics, Mechanics and Electrical Engineering, Montanuniversität Leoben, Franz Josef Strasse 18, 8700 Leoben, Austria.2 Tomsk Polytechnic University, Lenina Avenue 30, 634034 Tomsk, Russia. 3 Erich Schmid Institute of Materials Science, Austrian Academy of Sciences,Jahnstrasse 12, 8700 Leoben, Austria. 4 Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044,Japan. 5 International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan. 6 Graz Centrefor Electron Microscopy (ZFE), Steyrergasse 17, 8010 Graz, Austria. ✉email: gennadiy.murastov@unileoben.ac.at; aleksandar.matkovic@unileoben.ac.atCOMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschem 11234567890():,;http://crossmark.crossref.org/dialog/?doi=10.1038/s42004-023-00975-6&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1038/s42004-023-00975-6&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1038/s42004-023-00975-6&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1038/s42004-023-00975-6&domain=pdfhttp://orcid.org/0000-0002-7681-3118http://orcid.org/0000-0002-7681-3118http://orcid.org/0000-0002-7681-3118http://orcid.org/0000-0002-7681-3118http://orcid.org/0000-0002-7681-3118http://orcid.org/0000-0003-3701-8119http://orcid.org/0000-0003-3701-8119http://orcid.org/0000-0003-3701-8119http://orcid.org/0000-0003-3701-8119http://orcid.org/0000-0003-3701-8119http://orcid.org/0000-0002-1467-3105http://orcid.org/0000-0002-1467-3105http://orcid.org/0000-0002-1467-3105http://orcid.org/0000-0002-1467-3105http://orcid.org/0000-0002-1467-3105http://orcid.org/0000-0003-4016-1469http://orcid.org/0000-0003-4016-1469http://orcid.org/0000-0003-4016-1469http://orcid.org/0000-0003-4016-1469http://orcid.org/0000-0003-4016-1469http://orcid.org/0000-0001-8072-6220http://orcid.org/0000-0001-8072-6220http://orcid.org/0000-0001-8072-6220http://orcid.org/0000-0001-8072-6220http://orcid.org/0000-0001-8072-6220mailto:gennadiy.murastov@unileoben.ac.atmailto:aleksandar.matkovic@unileoben.ac.atwww.nature.com/commschemwww.nature.com/commschemMetallic nanoparticles (NPs) are widely used in photo-catalysis, surface-enhanced Raman spectroscopy(SERS), and plasmonics, due to their capability tostrongly couple the incoming light to a plasmonic response1–5. Toharness light-matter interaction in 2D material transition metaldichalcogenides (TMDCs)6,7 they’re combined with NPs viadifferent approaches including drop-casting8, dip-coating9,10,atomic layer deposition11,12, self-assembled layer13,14, and spon-taneous redox reaction15. Yielding with mixed-dimensionalheterostructures16, hybrid materials17, and heterojunctions18that have been effectively employed for various applicationsranging from hydrogen evolution reaction (HER) to light-emitting diodes and sensors19–25. For example, molybdenumdisulfide (MoS2) with deposited Au@Ag co-shell nanorattlesattenuated overpotential and reduced Tafel slope for the HER dueto plasmonic hot electron photocatalysis tuned by laser powerand wavelength26.Commonly in these hybrid structures, both the basal plane andthe edges of 2D materials are covered with NPs to optimize themfor SERS and optoelectronic devices with large active surfacearea27–31. This has been demonstrated by Rahaman et al., wherethey show localized surface plasmon resonance assisted by hotelectron transfer, resulting in anomalous Fröhlich interaction32.However, there are several drawbacks of the aforementionedmethods such as non-selective deposition, basal plane crystallinitydisruption of 2D materials and their straining.2D material-based nanoribbons (NRs) provide a promisingplatform to overcome these issues, as these systems offer a highedge-to-surface ratio. Since the edges predominantly serve asnucleation sites, the basal plane coverage is minimized. NRs havebeen employed for targeted drug delivery, molecular and gassensing, filtering, (photo-)catalytic reaction, electronics, andoptics24,33–38.Recently, spatially controlled deposition of metallic NPs and“nanoflowers” was demonstrated for transparent and non-transparent substrates utilizing the laser-induced photo-decom-position of [{Au10Ag12(C2Ph)20}Au3(PPh2(C6H4)3PPh2)3] [PF6]5complexes in different solutions39,40. Also, the high-precisionpatterning ability of the spot scanning system was utilized toselectively deposit NPs on the topmost surface of MoS2 2D flakesvia light-induced photoreduction of silver nitrate AgNO3solution41. The NPs were found more likely to be attached to thechemically active sides, i.e., intrinsic and laser-induced defectsregions41. Therefore, the edges of the flakes or the 2D material-based NRs are expected to serve as primary nucleation sites forsilver seeds. This was observed in our previous study for grapheneNRs decorated by metallic NPs via the photo-activated reductionof Ag ions at the edges via electron transfer from graphene42.In this work, we perform silver nanoparticle (AgNP) edge-specific decoration of WSe2 flakes and their NRs. We demonstratethe tunable particle density along the NR edges in-line with thelaser fluence. Protected with an organic mask—a by‑product ofthe NR fabrication method—the basal plane of NR remainsencapsulated while the NR edges are simultaneously decoratedwith metallic NPs. Obtained hybrid systems have shown theenhancement in Raman signal and photocatalytic activity byconversion of 4-nitrobenzenthiol (4-NBT) to p, p′-dimercaptoa-zobenzene (DMAB).Results and discussionEdge-specific decoration of 2D NR networks. The NR networksof WSe2 were prepared by a method previously established byAslam et al. in ref. 42. It utilizes needle-like nanostructures ofpara-hexaphenyl C36H26 (6P, p-6P) grown on top of the 2D flakesand acts as a mask for the following oxygen plasma treatment.Here, we employ a single-step treatment to simultaneouslyreduce, merge and deposit AgNPs in the silver ionic solution viadirect light irradiation of immersed NR samples. Moreover, we varythe power of a continuous-wave 637 nm laser from 200 μW to35mW and adjust the scanning speed from 5 to 50 μm s-1 to tunethe total applied laser fluence in the range of 1 to 300 μJ μm-2(detailed information is given in the Supplementary Note 1).Aiming to understand the mechanism behind the NPformation and to emphasize the role of the 2D material edges,we focus on the edge-specific decoration of the photoactivequasi-1D WSe2 NRs. The 6P organic masks remained on top ofthe ribbon’s networks to prevent tungsten oxide formation duringlaser exposure43,44. The organic ‘caps’ also help to enhance theedge-selectivity of silver NPs deposition. The scheme of thedeposition process and the double-side arrays of AgNPs obtainedby atomic force microscopy (AFM) and scanning electronmicroscopy (SEM) are presented in Fig. 1.Direct laser illumination of the AgNO3 solution does not createNPs while in the presence of WSe2 the light triggers the reductionof a silver ion to the neutral state due to the release of photo-excited electrons from NRs. Ag0 seed acts as a source for furtherNPs growth. The NR cross-section view is schematicallyillustrated in Figs. 1b, c with a single-step reduction of silverions and NP assembly, respectively. As the electrons originatemostly from the edge defects of the 2D TMDC NRs, the seeds areanchored to them, and the decoration with AgNPs remainsexclusive to the edges. Also, the organic ‘caps’ on top of NRs serveas a shield and a guide for the NPs deposition. An overview of theobtained WSe2 NR network decorated with NPs anchored to theribbon edges is presented in Fig. 1d.Figures 1e, f present in higher magnification images of WSe2NR junction with AgNPs. Most of the AgNPs stick to the edges.In the case of the TMDC NR networks, and for the properlytuned growth parameters, non‑edge specific nucleation or shiftingof the NPs during the rinsing steps was found to occur for lessthan 1% of all detected NPs within the illuminated area. At thesame time, the basal plane of the NRs is protected by the organiclayer, which prevents any NP deposition on the NR top surface.The NRs retain most of the structural and electronic propertiesof the original 2D TMDC flakes42. Therefore, the sameedge‑specific decoration process was also tested on the non‑pat-terned WSe2 flakes without an organic mask. The edges of theflakes, with respect to the basal plane of the 2D sheet, inevitablyintroduce intrinsic inhomogeneity and defect complexes. There-fore, the edge‑specific decoration process also occurs for theflakes, as demonstrated for the edge of the mechanically cleavedWSe2 layers (Fig. 2a). Corresponding Raman spectra obtainedfrom the bare flake and the NPs on the edge are presented inFig. 2b.Usually, the Raman spectrum of WSe2 is described by severalpeaks originating from the interlayer breathing mode A1g, the in-plane displacement E1g of the chalcogen atoms, the E2g2 shearmode corresponding to the vibration of two rigid layers againsteach other47. The overtone of the LA phonon branch at the Mpoint of the Brillouin zone can be observed in Raman. It iscommonly noted as 2LA(M) alongside the prominent B2g1 peakand is associated with an A-symmetry first-order modecorresponding to an interlayer vibration18,45–48. In Fig. 2b, thepresence of the A1g (250 cm-1), E2g2 (248 cm-1), B2g1 (308 cm-1),2LA(M) (~260 cm-1) modes together is attributed to the thicknessof 3 trilayer (3TL) WSe245.Near the NP decorated edges, A1g and E2g2 were found to forma single A+ E mode at ~251 cm-1 associated with the out-of-plane vibration in WSe2. No laser-induced tungsten (tri-)oxidesWO3-x formation49 were found supported with almost zero-lineRaman in Fig. 2b. The dashed line represents O-W-O stretchingARTICLE COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-62 COMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschemwww.nature.com/commschemmodes at 717 cm-1 and 807 cm-1 for the hybrid system ofAg(25 nm)-WO349.Figure 2c demonstrates one of the densest NP-decoratednetworks obtained in our experiments. Corresponding Ramanspectra of AgNP decorated WSe2 NRs and untreated NRs arepresented in Fig. 2d. It contains the unique features coming frominactive resonant phonons such as E1g (~175 cm-1), TA(M)(~205 cm-1) which could be attributed to the z¯(xx)z polarizedconfiguration in double and multilayer system of WSe245,48.Further, decorated NRs exhibit the second‑order features of WSe2Raman modes due to double and triple plasmon resonancemechanism46 and are obtained as enhanced peaks at ~358 cm-1,~372 cm-1, and ~394 cm-1. Lastly, compared to the untreatedWSe2 NRs, the decorated ones bring a strong luminescencebackground in the Raman signal assigned to the possibility of theheterojunction formation18.The same WSe2 NR network as for Fig. 2c was analyzed byenergy dispersive X-ray (EDX) spectrometry. The presence ofsilver is confirmed by tracking the Ag L peak during the mapmeasurements. To obtain a better signal-to-noise ratio, spectralmap points from the areas labeled with dashed circles in Fig. 2ewere merged and are presented as an integrated spectrum inFig. 2g. The same is done for Se peak from the basal plane of theNR given in Fig. 2f. Applying the edge‑selective NP decorationprocess to the NR networks benefits from their enhancededge‑to‑surface ratio42 and provides a possible pathway toincorporate these hybrid nanostructures in sensing and catalyticapplications19,36,38.AgNP distribution. To exploit the tunability of the light-assisteddeposition method over the AgNP’s distribution in the patternedareas, we performed a series of experiments with different laserpower, time, and scanning speeds. The results presented in Fig. 3are given as a function of laser fluence, while all varying para-meters are included in Supplementary Table 1. A fairly goodstability and reproducibility in size were achieved, especiallyconsidering that the proposed edge-specific laser-treatmentmethod is a solution-based process (Fig. 3d–f). Also, NPs growthwas found to be very similar on both predominantly zigzag andarmchair edge types. This can be seen at ~90° joints between theNRs from Fig. 3b, c (more details in Supplementary Fig. 1). Thereare still a few NPs that could be found not anchored to the edgesdue to thermal fluctuations and diffusion in water.The size distribution of the deposited AgNPs slightly deviatesbetween the samples (see the error bars in Fig. 3g). Surprisingly,the average NP diameter with a mean value of ~32 nm remainsthe same for the laser fluence up to 300 μJ μm-2. This is attributedto the limited number of seeds available in a short reaction time.Essentially, the self‑stabilizing particle size would support ourhypothesis that the creation of new nucleation spots prevails as adominant mechanism over the merging process of the NPs. Thisis further supported by the fact that NP merging is ratherslow50,51.Also, we found the correlation between the laser fluence andthe linear NP density along the NR edges. We did not observe alot of agglomerates and large particles among the deposited NPs,instead, the NPs nucleation linear density varied from ~2 to ~12NPs per μm of the NR length as laser fluence increased (Fig. 3h).The results imply that this is a self-saturated edge-driven process,i.e., the reduced Ag+ competes for the edge’s nucleation spotleading to the dense deposition instead of the larger particleformation. Contrary to this, in a colloidal solution the triangle-Fig. 1 Edge-specific WSe2 nanoribbons decorated with silver nanoparticles. a The sketch of the laser-scanning NP’s deposition process in the silver ionicsolution. b The main mechanism of ‘seeds’ formation via silver ions reduction under the strong laser fluence. c The light-assisted NP merging on the edge ofNR. d The overview (AFM topography, z scale is 60 nm) of the WSe2 NR network decorated with AgNP. e, f A zoom-in region marked by the red square ind presenting the surface topography (AFM, z scale is 28 nm) and scanning electron microscopy (SEM) images of the WSe2 NR network decoratedwith AgNPs.COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-6 ARTICLECOMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschem 3www.nature.com/commschemwww.nature.com/commschemand the rod-shaped NPs within hundreds of nm in size could beobtained via the plasmon oscillation enhancement merger in afew hours of the continuous light-annealing50–52.It should be mentioned that no edge decoration of WSe2 NRscapped with 6 P is observed with the laser fluence less than~5 μJ μm-2. Compared to the WSe2 flake, 5 times higher fluence isneeded to induce edge-specific AgNPs formation on NRs.The sources of photo‑excited electrons and the influence of theorganic layer on the NP growth. As we highlighted before, theWSe2 edges are a key factor to perform the AgNO3 reductionand to anchor the NPs to the edges of the NR networks. In theperformed NP growth experiments, the 6P organic capremained partly on the NR’s basal plane. Further, 6P is knownas a photoluminescent material53. Therefore, 6P caps shouldFig. 2 SEM and Raman spectroscopy on the WSe2 flake and nanoribbon network with edge-specific decoration by silver nanoparticles. a WSe2 flake’sedge-specific assembly of the AgNPs with a laser fluence of ~1.3 μJ μm-2. b Comparison of Raman spectra between the intact area and NP decorated edge.The SERS signal on Ag(25 nm)-WO3 system (dashed line) was adapted with permission from ref. 49. © 2014 Springer Nature. c WSe2 NR’s edge-specificAgNPs decoration with a laser fluence of ~100 μJ μm-2. This region was laser scanned twice to obtain more NPs. d The Raman spectra with and without NPdeposition. The Raman peaks marked with the red stars are attributed to the second-order features excited with the double and the triple resonancemechanisms due to plasmon resonance46. EDX elemental maps performed for silver e and selenium f at the same area as on panel c. g Correspondingenergy dispersive X-ray spectra to the NR edges (Ag rich area) and NR basal plane (Se rich area).ARTICLE COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-64 COMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschemwww.nature.com/commschemalso be able to initiate the Ag seed formation assisted by strongcoherent light.To investigate the impact of 6P on the proposed laser‑assistedNP growth, we have performed a negative experiment onhexagonal boron nitride NRs with and without 6P caps (Fig. 4).Since hBN is an insulator (~6 eV bandgap)54, we can assume thatphoto‑excited electrons cannot be generated with our ~1.9 eV laser.However, essentially identical 6P organic nanostructures can begrown on hBN55 and hBNNR networks can be fabricated using thesame method as was employed for WSe2 NRs42. Furthermore, hBNis more thermally stable and can withstand the prolonged vacuumannealing needed to desorb 6P56. This allowed us to test the NPdecoration on clean hBN nanoribbons, as a negative experiment.Therefore, we could test the influence of the 6P caps in NP seeding.Both WSe2 and 6P can actively support the growth of NPs onthe edges by donating the excited electrons and promoting thenucleation centers, yielding the dense AgNPs NR edge decorationat ~80 μJ μm-2 (Fig. 4a). Also, the hBN NRs covered with 6Penable the AgNPs decoration with the laser fluence of~102 μJ μm-2 (Fig. 4b). However, at higher fluence (above400 μJ μm-2) 6P decomposition starts to occur providing anadditional electron source for the reduction process. This yieldsalso non-edge-specific deposition on the ribbon’s basal plane aswell as on the bare substrate near the ribbons.The deposition process on hBN capped with 6P is ~5 times lessefficient in comparison to WSe2 (Fig. 4a, b) as the process ismostly driven by the 6P source. This can be simply attributed tothe fact that hBN, unlike WSe2, is not promoting the nucleationof AgNPs. Opposite results were obtained for MoS2 and WS2NRs. In these cases, and within the explored parameter space, thesulfide-based 2D materials were easily oxidized forming theAg2MoO4 dendrites and WOx, Ag2S, structure as shown inSupplementary Figs. 2–3.Finally, as a confirmation that the NP growth process is alsopartly driven by the photo‑excited electrons from the organics,the decoration process was repeated on hBN NRs without 6P caps(Fig. 4c). Almost zero AgNPs were observed on the cleaned hBNNRs, even with a higher laser fluence ~347 μJ μm-2 applied.Interestingly, the same finding was obtained on PtSe2 NRs likelydue to lower light-matter interaction. Still, randomly sedimentedFig. 3 Multilayer WSe2 nanoribbon networks irradiated with different laser fluences. SEM images of AgNPs deposited with a relatively low laser fluenceof a ~15 μJ μm-2, b ~80 μJ μm-2 and c ~300 μJ μm-2. d, e, and f NPs size distribution (diameter of AgNP) calculated from a, b, and c, respectively. The countsare normalized to one to have a uniform scale. g The average deviation of AgNP size along the NR edges. h The evaluated linear NP density depends on theapplied laser fluence. Irradiation with a laser fluence of more than 400 µJ μm-2 leads to NP agglomeration. The error bars in g, h present a standarddeviation.COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-6 ARTICLECOMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschem 5www.nature.com/commschemwww.nature.com/commschemNPs were occasionally observed, but no systematic deposition, aspointed in Fig. 4c, what can be attributed to a liquid-basedprocess and the presence of natural contaminants in the solution.Light-mediated catalysis on AgNPs decorated edges. As apotential system for HER, the conversion of 4-NBT to 4-ABT andp, p′-dimercaptoazobenzene on plasmonic NPs are highly used inbig pharma industries57–59. Here, we demonstrate the possibilitiesof our AgNP-decorated NRs as a platform for the photocatalyticconversion of 4-NBT molecules to DMAB.Raman spectroscopy allows us to track chemical compositionchanges in real-time in a non-destructive manner. No moleculardegradation, peak shifting, or quenching of the Raman peaksfrom the 4-NBT powder was observed with direct laser exposureup to 100mW for a 532 nm wavelength laser irradiation. For thecatalysis experiments, we used freshly prepared AgNPs tominimize the metal oxide formation in ambient conditions.Figure 5a illustrates the plasmon-assisted surface catalyticreaction to perform the dimerization of 4-NBT to DMAB. Bymonitoring the main peak located at ~1330 cm−1 assigned to thesymmetric stretching vibration of the nitro group ν(NO2) in 4-NBT, we could track the degree of conversion. The other distinctpeaks in Fig. 5b are attributed to the C–C ring stretching(~1575 cm−1) and C−S vibration (~1100 cm−1)60,61.After laser irradiation in the presence of AgNPs, all Ramanpeaks, except ~1575 cm−1 one, change drastically. The newFig. 5 Demonstration of photoactive silver nanoparticles behavior via photocatalysis of 4-nitrobenzenthiol probe molecules intop, p′-dimercaptoazobenzene with the green Raman laser (532 nm). a The dimerization reaction of 4-NBT on metallic NPs via ‘hot’ electron doping.b Raman spectra of 4-NBT powder and 4-NBT laser-induced conversion to DMAB in the presence of AgNP at the NR edge.Fig. 4 SEM images of the WSe2 nanoribbon and hBN nanoribbon networks with and without para-hexaphenyl organic mask. a AgNP’s double-edgearray on the WSe2 NR network with 6 P on top. b hBN NR with 6P on top of the network immersed in the AgNO3 solution and irradiated with a red laser(637 nm). c No AgNPs deposited on the cleaned hBN NR network. The scale bar is 1 μm.ARTICLE COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-66 COMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschemwww.nature.com/commschemcombined peak of νCC+ δCH ring vibration appeared at~1435 cm−1, evidencing the successful photocatalytically drivenDMAB formation as shown in Fig. 5b.These experiments confirm that the deposited AgNPs via theproposed edge-specific method show high photocatalytic activity.Almost all of 4-NBT was transformed to the DMAB after a fewseconds under 0.1 mW@532 nm Raman laser as no ν(NO2) peakwas visible anymore in the Raman spectra (Fig. 5b, black curve).The NP-decorated NRs perform similarly to conventional AgNP-based SERS-substrates62,63.Conclusion. We proposed a solution‑based method foredge‑specific laser-assisted NP formation. This method isdemonstrated using 2D WSe2 flakes and their NRs. Photonsexcite the electrons at the TMDC edges immersed in the AgNO3solution, reducing the silver ions and leading to the formation ofAgNP seeds that grow and remain anchored to the edges. Thismethod is pushed to the limit by employing nanopatterned net-works of WSe2 NRs that enhance the edge‑to‑surface ratio byorders of magnitude compared to the pristine 2D flakes. A con-stant laser fluence is needed to merge the seeds into NPs. Thisresults in double linear arrays of NPs along the NRs with anaverage diameter of ~32 nm, which is attributed to short reactiontime and a limited number of seeds. Remaining the average size ofNP fixed, the linear NPs density along the NR edge can becontrolled by tuning the laser fluence. Freshly deposited AgNPsresult in an increase in the Raman signal of WSe2 NRs and anenhancement of the resonant modes. Further, the high photo-catalytic activity of the AgNPs/NRs system was demonstrated bythe full conversion of 4-NBT to DMAB.The edge-selective decoration of metallic NPs is an approachfor building mixed-dimensional heterostructures and heterojunc-tions with high lateral precision and synergy between optoelec-tronic properties of 2D materials and the strong light coupling ofplasmonic NPs. We expect that this will yield much betterelectronic properties of the WSe2 NRs than of the basal planedecorated thin films. Decoration of the basal plane can lead todamage of the 2D semiconductor crystal structure and thereforean increased scattering rate of the free carriers. Consequently, theelectronic properties of the 2D semiconductor could besignificantly degraded making potential electronic excitation orreadout impossible.This laser-assisted decoration method can be extended and usedin tandem with other strategies and other 2D materials to develop,pattern, enhance and investigate the complex micro- and nano-properties of materials and systems. Our proposed edge‑specificand laser‑assisted NP decoration method of 2D materials opens anew pathway to develop ultra-sensitive devices based on the hybridheterostructures and heterojunctions between 2D materials, theirreactive edges, and metallic NPs, with potential impact mainly onoptoelectronic, catalytic, and plasmonic systems.MethodsNR network fabrication. NR network fabrication was described in ref. 42. Briefly,hot wall epitaxy was used to deposit the organic mask containing 6P (p-6P orC36H26 consists of six phenyl rings connected by single sp² carbon–carbon bondsforming a rod-like conjugated molecule) on top of 2D flakes (WSe2, MoS2, WS2,graphene, and hBN) followed by reactive oxygen ion etching. The obtained NRnetworks were further used for AgNP decoration.Solution preparation. The silver nitrate was purchased from Sigma Aldrich (99.9 %chemical grade, powder). 1.7 mg of AgNO3 was dissolved in 10ml of DI water toobtain the 1mM silver ionic solution used for further NPs deposition.Deposition setup. A homemade 3D-printed microscope coupled with a red laserdiode (RLT 635-180MGE, with a central peak wavelength of 637 nm, a maximumpower of 180 mW) was used for the laser treatment of the sample. The laser powerwas controlled by Keithley 2400 current source meter. The average spot size givenby the 20× objective was estimated to be 5 μm. A 3D printed XY stage64 allows thesample scanning with respect to the fixed laser spot position.6P cleaning. The NR networks with organic masks on top were annealed in highvacuum (10-6 mbar) with a constant temperature of 200 °C for at least 6 h. Thesuccessful removal of 6P was confirmed by Raman spectroscopy and by comparingthe AFM images before and after heating.Atomic force microscopy (AFM). The samples were measured using the scanningprobe microscope Horiba/AIST-NT Omegascope AFM system in ambient condi-tions. Topography profiles were obtained in tapping mode with high-frequencyprobes Nunano Scout (spring constant of 42 Nm-1, resonant frequency ~ 350 kHz,and tip radius of 5 nm).Scanning electron microscopy (SEM). The scanning electron microscopymicrographs were obtained using a field-emission scanning electron microscopeZeiss LEO 1525 to evaluate the NP size and distribution. The micrographs wererecorded with an acceleration voltage of 20 kV and an aperture size of 60 μm insecondary electron detection mode.EDX mapping. Zeiss Sigma 300 VP coupled with EDS Detector Oxford SDD 80was used to obtain the elemental map from the decorated WSe2 nanoribbonscovered within 5–10 nm carbon coating to minimize surface changing and imagedrifting during the long-term measurements.NP edge-decoration and photocatalysis experiments. 5 μl of 1 mM AgNO3 weredropped on the samples. The thin glass was used to reduce water evaporationduring the laser scanning. The constant spacing of 400 μm between the surface andglass was maintained by polydimethylsiloxane small sheets (Gel-Pak-DLG-X4)attached to the edges of Si substrate. The 3D-printed deposition setup is used forpatterning.For the photocatalytic experiment, the 4-NBT powder was dissolved in DI watermixed with ethanol in a ratio of 50:50 to have a concentration of 0.1 mM. 2D NRnetworks decorated with AgNPs were immersed into a solution for several hoursand rinsed with DI water several times prior to Raman measurements.Raman spectroscopy. Raman measurements were performed using a HoribaLabRam HR Evolution confocal Raman spectrometer using 600 lines mm-1 and1800 lines mm-1 gratings. A 532 nm laser source was used to excite the sampleswith an excitation power of 0.1–3.2 mW. The laser spot was focused by a 100×, 0.9NA objective.Data availabilityThe authors declare that all the data supporting the findings of this study are availablewithin the article or available from the corresponding authors on reasonable request.Received: 17 February 2023; Accepted: 3 August 2023;References1. Roguska, A., Kudelski, A., Pisarek, M., Opara, M. & Janik-Czachor, M.Surface-enhanced Raman scattering (SERS) activity of Ag, Au and Cunanoclusters on TiO2-nanotubes/Ti substrate. Appl. Surf. Sci. 257, 8182–8189(2011).2. Wang, L. et al. SERS-based test strips: principles, designs and applications.Biosens. Bioelectron. 189, 113360 (2021).3. Li, C. et al. Towards practical and sustainable SERS: a review of recentdevelopments in the construction of multifunctional enhancing substrates. J.Mater. Chem. C. Mater. Opt. Electron. Devices 9, 11517–11552 (2021).4. Liu, C., Xu, D., Dong, X. & Huang, Q. A review: research progress of SERS-based sensors for agricultural applications. Trends Food Sci. Technol. 128,90–101 (2022).5. Langer, J. et al. Present and Future of Surface-enhanced Raman scattering.ACS Nano 14, 28–117 (2020).6. Wurstbauer, U., Miller, B., Parzinger, E. & Holleitner, A. W. Light–matterinteraction in transition metal dichalcogenides and their heterostructures. J.Phys. D. Appl. Phys. 50, 173001 (2017).7. Deilmann, T., Rohlfing, M. & Wurstbauer, U. Light-matter interaction in vander Waals hetero-structures. J. Phys. Condens. Matter 32, 333002 (2020).8. Kaliyaraj Selva Kumar, A., Zhang, Y., Li, D. & Compton, R. G. A mini-review:how reliable is the drop casting technique? Electrochem. Commun. 121,106867 (2020).COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-6 ARTICLECOMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschem 7www.nature.com/commschemwww.nature.com/commschem9. Wu, L. et al. Dip-coating process engineering and performance optimizationfor three-state electrochromic devices. Nanoscale Res. Lett. 12, 390 (2017).10. Barad, H.-N., Kwon, H., Alarcón-Correa, M. & Fischer, P. Large areapatterning of nanoparticles and nanostructures: current status and futureprospects. ACS Nano 15, 5861–5875 (2021).11. Lee, S. et al. Atomic layer deposited Pt nanoparticles on functionalized MoS2as highly sensitive H2 sensor. Appl. Surf. Sci. 571, 151256 (2022).12. Sivakov, V. A. et al. Silver coated platinum core-shell nanostructures onetched Si nanowires: atomic layer deposition (ALD) processing andapplication in SERS. Chemphyschem 11, 1995–2000 (2010).13. Madhu, M., Chao, C.-M., Ke, C.-Y., Hsieh, M.-M. & Tseng, W.-L. Directedself-assembly of Ag-deposited MoS quantum dots for colorimetric, fluorescentand fluorescence-lifetime sensing of alkaline phosphatase. Anal. Bioanal.Chem. 414, 1909–1919 (2022).14. Binu, S. et al. Photoinduced formation of Ag nanoparticles on the surface ofAs2S3/Ag thin bilayer. Mater. Res. Express 1, 045025 (2014).15. Kim, J., Byun, S., Smith, A. J., Yu, J. & Huang, J. Enhanced electrocatalyticproperties of transition-metal dichalcogenides sheets by spontaneous goldnanoparticle decoration. J. Phys. Chem. Lett. 4, 1227–1232 (2013).16. Jariwala, D., Marks, T. J. & Hersam, M. C. Mixed-dimensional van der Waalsheterostructures. Nat. Mater. 16, 170–181 (2017).17. Rasuli, H. & Rasuli, R. Nanoparticle-decorated graphene/graphene oxide:synthesis, properties and applications. J. Mater. Sci. 58, 2971–2992 (2023).18. Wang, L.-Y. et al. Photoexcitation and radiation regulation mechanism of Aganchoring WSe2 heterojunction with plasma coupling effect. Appl. Surf. Sci.591, 153240 (2022).19. Ling, N. et al. Active hydrogen evolution on the plasma-treated edges ofWTe2. APL Mater. 9, 061108 (2021).20. Wen, X., Gong, Z. & Li, D. Nonlinear optics of two‐dimensional transitionmetal dichalcogenides. InfoMat 1, 317–337 (2019).21. Guo, H. et al. All-two-dimensional-material hot electron transistor. IEEEElectron Device Lett. 39, 634–637 (2018).22. Turker, F., Rajabpour, S. & Robinson, J. A. Material considerations for thedesign of 2D/3D hot electron transistors. APL Mater. 9, 081103 (2021).23. Michaelis de Vasconcellos, S. et al. Single‐photon emitters in layered Van derWaals materials. Phys. Status Solidi B Basic Res. 259, 2100566 (2022).24. Alavi, S. K. et al. Photodetection using atomically precise graphenenanoribbons. ACS Appl. Nano Mater. 3, 8343–8351 (2020).25. Lee, K., Duan, X., Hersam, M. C. & Kim, J. Fundamentals and applications ofmixed-dimensional heterostructures. APL Mater. 10, 060402 (2022).26. Kang, Y. et al. Plasmonic hot electron enhanced MoS2 photocatalysis inhydrogen evolution. Nanoscale 7, 4482–4488 (2015).27. Li, X. et al. Optimizing thermoelectric performance of MoS2 films byspontaneous noble metal nanoparticles decoration. J. Alloy. Compd. 781,744–750 (2019).28. Lampeka, Y. D. & Tsymbal, L. V. Nanocomposites of two-dimensionalmolybdenum and tungsten dichalcogenides with metal particles: Preparationand prospects for application. Theor. Exp. Chem. 51, 141–162 (2015).29. Hong, X. et al. A universal method for preparation of noble metalnanoparticle-decorated transition metal dichalcogenide nanobelts. Adv.Mater. 26, 6250–6254 (2014).30. Petit, P. et al. Study of the thermal stability of supported catalyticnanoparticles for the growth of single-walled carbon nanotubes with narrowdiameter distribution by chemical vapor deposition of methane. J. Phys. Chem.C. Nanomater. Interfaces 116, 24123–24129 (2012).31. Alcaraz Iranzo, D. et al. Probing the ultimate plasmon confinement limits witha van der Waals heterostructure. Science 360, 291–295 (2018).32. Rahaman, M., Aslam, M. A., He, L., Madeira, T. I. & Zahn, D. R. T. Plasmonichot electron induced layer dependent anomalous Fröhlich interaction in InSe.Commun. Phys. 4, 172 (2021).33. Luo, S. et al. Recent advances in graphene nanoribbons for biosensing andbiomedicine. J. Mater. Chem. B Mater. Biol. Med. 9, 6129–6143 (2021).34. Johnson, A. P., Gangadharappa, H. V. & Pramod, K. Graphene nanoribbons: apromising nanomaterial for biomedical applications. J. Control. Release 325,141–162 (2020).35. Johnson, A. P. et al. Graphene nanoribbon: an emerging and efficient flatmolecular platform for advanced biosensing. Biosens. Bioelectron. 184, 113245(2021).36. Liang, F.-X. et al. Plasmonic hollow gold nanoparticles induced high-performance Bi2S3 nanoribbon photodetector. Nanophotonics 6, 494–501(2017).37. Wang, L. et al. Plasmonic silver nanosphere enhanced ZnSe nanoribbon/Siheterojunction optoelectronic devices. Nanotechnology 27, 215202 (2016).38. Kuru, C., Choi, D., Choi, C., Kim, Y. J. & Jin, S. Palladium decoratedgraphene-nanoribbon network for enhanced gas sensing. J. Nanosci.Nanotechnol. 15, 2464–2467 (2015).39. Bashouti, M. Y. et al. Spatially-controlled laser-induced decoration of 2D and3D substrates with plasmonic nanoparticles. RSC Adv. 6, 75681–75685 (2016).40. Povolotckaia, A. et al. Plasmonic carbon nanohybrids from laser-induceddeposition: controlled synthesis and SERS properties. J. Mater. Sci. 54,8177–8186 (2019).41. Lei, Y. T. et al. One-step selective formation of silver nanoparticles on atomiclayered MoS2 by laser-induced defect engineering and photoreduction. J.Mater. Chem. C. Mater. Opt. Electron. Devices 5, 8883–8892 (2017).42. Aslam, M. A. et al. Single-crystalline nanoribbon network field effecttransistors from arbitrary two-dimensional materials. Npj 2D Mater. Appl. 6,76 (2022).43. Zhu, C. et al. Direct laser patterning of a 2D WSe2 logic circuit. Adv. Funct.Mater. 31, 2009549 (2021).44. Tan, C. et al. Laser-assisted oxidation of multi-layer tungsten diselenidenanosheets. Appl. Phys. Lett. 108, 083112 (2016).45. Luo, X. et al. Effects of lower symmetry and dimensionality on Raman spectrain two-dimensional WSe2. Phys. Rev. B. 88, 195313 (2013).46. del Corro, E. et al. Excited excitonic states in 1L, 2L, 3L, and bulk WSe2observed by resonant Raman spectroscopy. ACS Nano 8, 9629–9635(2014).47. Zhao, W. et al. Lattice dynamics in mono- and few-layer sheets of WS2 andWSe2. Nanoscale 5, 9677–9683 (2013).48. Shi, W. et al. Raman and photoluminescence spectra of two-dimensionalnanocrystallites of monolayer WS2 and WSe2. 2d Mater. 3, 025016 (2016).49. Xu, L., Yin, M.-L. & Liu, S. F. Ag(x)@WO3 core-shell nanostructure for LSPenhanced chemical sensors. Sci. Rep. 4, 6745 (2014).50. Stamplecoskie, K. G. & Scaiano, J. C. Light emitting diode irradiation cancontrol the morphology and optical properties of silver nanoparticles. J. Am.Chem. Soc. 132, 1825–1827 (2010).51. Jin, R. et al. Controlling anisotropic nanoparticle growth through plasmonexcitation. Nature 425, 487–490 (2003).52. Jin, R. et al. Photoinduced conversion of silver nanospheres to nanoprisms.Science 294, 1901–1903 (2001).53. Simbrunner, C. et al. Color tuning of nanofibers by periodic organic-organichetero-epitaxy. ACS Nano 6, 4629–4638 (2012).54. Watanabe, K., Taniguchi, T. & Kanda, H. Direct-bandgap properties andevidence for ultraviolet lasing of hexagonal boron nitride single crystal. Nat.Mater. 3, 404–409 (2004).55. Matković, A. et al. Epitaxy of highly ordered organic semiconductor crystallitenetworks supported by hexagonal boron nitride. Sci. Rep. 6, 38519 (2016).56. Matković, A. et al. Probing charge transfer between molecular semiconductorsand graphene. Sci. Rep. 7, 9544 (2017).57. Kim, K., Lee, I. & Lee, S. J. Photolytic reduction of 4-nitrobenzenethiol on Aumediated via Ag nanoparticles. Chem. Phys. Lett. 377, 201–204 (2003).58. Ren, X. et al. Observing reduction of 4-nitrobenzenthiol on gold nanoparticlesin situ using surface-enhanced Raman spectroscopy. Phys. Chem. Chem. Phys.15, 14196 (2013).59. Golubev, A. A., Khlebtsov, B. N., Rodriguez, R. D., Chen, Y. & Zahn, D. R. T.Plasmonic heating plays a dominant role in the plasmon-inducedphotocatalytic reduction of 4-nitrobenzenethiol. J. Phys. Chem. C. Nanomater.Interfaces 122, 5657–5663 (2018).60. Skadtchenko, B. O. & Aroca, R. Surface-enhanced raman scattering ofp-nitrothiophenol molecular vibrations of its silver salt and the surfacecomplex formed on silver islands and colloids. Spectrochim. Acta A Mol.Biomol. Spectrosc. 57A, 1009–1016 (2001).61. Ye, J. et al. Excitation wavelength dependent surface enhanced Ramanscattering of 4-aminothiophenol on gold nanorings. Nanoscale 4, 1606 (2012).62. Dong, B., Fang, Y., Chen, X., Xu, H. & Sun, M. Substrate-, wavelength-, andtime-dependent plasmon-assisted surface catalysis reaction of4-nitrobenzenethiol dimerizing to p,p’-dimercaptoazobenzene on Au, Ag, andCu films. Langmuir 27, 10677–10682 (2011).63. Dai, Z. G. et al. In situ Raman scattering study on a controllable plasmon-driven surface catalysis reaction on Ag nanoparticle arrays. Nanotechnology23, 335701 (2012).64. McDermott, S. et al. Multi-modal microscopy imaging with the OpenFlexureDelta Stage. Opt. Express 30, 26377–26395 (2022).AcknowledgementsThis work has been supported by the Austrian Science Fund (FWF der Wissenschafts-fonds) through project number I4323-N36 and START grant number Y1298-N, RussianFoundation for Basic Research (RFBR, project number 19-52-14006). K.W. and T.T.acknowledge support from the JSPS KAKENHI (Grant Numbers 19H05790, 20H00354and 21H05233). A.L. acknowledges the funding of Austrian Science Fund (FWF) throughproject number T891-N36. The authors would also like to thank the AFM/Raman facilityof the Department of Applied Geosciences and Geophysics at Montanuniversität Leoben.This work was supported by the European Union Horizon 2020 program (grant No.823717_ESTEEM3). The purchase of the SEM system was enabled by the project“HRSM-Projekt ELMINet Graz-Korrelative Elektronenmikroskopie in den Bio-wissenschaften” (i.e., cooperation within “BioTechMed-Graz”, a research alliance of theARTICLE COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-68 COMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschemwww.nature.com/commschemUniversity of Graz, the Medical University of Graz, and the Graz University of Tech-nology), which was financed by the Austrian Federal Ministry of Education, Science, andResearch (BMBWF).Author contributionsR.R. and A.M. conceived the concept. G.M. wrote the manuscript under the supervisionby R.R. and A.M. G.M. designed and performed the experiments, fabricated the samples,and processed the data. M.A.A. contributed to the sample preparation and to the dataanalysis. A.L., S.W., and M.N. performed the SEM/EDX experiments and EDS dataanalysis. H.T. designed AgNP’s deposition protocol. K.W. and T.T. provided hBNcrystals. C.T. and E.S. contributed to the main text. All authors discussed the results,contributed to the analysis, and commented on the manuscript.Competing interestsThe authors declare no competing interests.Additional informationSupplementary information The online version contains supplementary materialavailable at https://doi.org/10.1038/s42004-023-00975-6.Correspondence and requests for materials should be addressed to Gennadiy Murastovor Aleksandar Matkovic.Peer review information Communications Chemistry thanks the anonymous reviewersfor their contribution to the peer review of this work. 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To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.© The Author(s) 2023COMMUNICATIONS CHEMISTRY | https://doi.org/10.1038/s42004-023-00975-6 ARTICLECOMMUNICATIONS CHEMISTRY |           (2023) 6:166 | https://doi.org/10.1038/s42004-023-00975-6 | www.nature.com/commschem 9https://doi.org/10.1038/s42004-023-00975-6http://www.nature.com/reprintshttp://creativecommons.org/licenses/by/4.0/http://creativecommons.org/licenses/by/4.0/www.nature.com/commschemwww.nature.com/commschem Photoinduced edge-specific nanoparticle decoration of two-dimensional tungsten diselenide nanoribbons Results and discussion Edge-specific decoration of 2D NR networks AgNP distribution The sources of photo‑excited electrons and the influence of the organic layer on the NP growth Light-mediated catalysis on AgNPs decorated edges Conclusion Methods NR network fabrication Solution preparation Deposition setup 6P cleaning Atomic force microscopy (AFM) Scanning electron microscopy (SEM) EDX mapping NP edge-decoration and photocatalysis experiments Raman spectroscopy Data availability References References Acknowledgements Author contributions Competing interests Additional information