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## Creator

Hajime Suzuki, [Shusaku Shoji](https://orcid.org/0000-0002-8481-2633), Fernando Garcia‐Escobar, Tomoya Tashiro, [Hideki Abe](https://orcid.org/0000-0002-8392-7586), [Keisuke Takahashi](https://orcid.org/0000-0002-9328-1694)

## Rights

This is the peer reviewed version of the following article: Suzuki Hajime, Shoji Shusaku, Garcia-Escobar Fernando, Tashiro Tomoya, Abe Hideki, Takahashi Keisuke, Phys. Status Solidi RRL, 2025, 19, e2500298, which has been published in final form at https://doi.org/10.1002/pssr.202500298. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Red Phosphorus‐Induced Transformation of Gold Mesh into Crystalline Gold Phosphide Mesh](https://mdr.nims.go.jp/datasets/e4ade9d5-e5c4-4b28-b169-e2768200fddd)

## Fulltext

Red Phosphorus-Induced Transformation of Gold Mesh into Crys-talline Gold Phosphide MeshHajime Suzuki* Shusaku Shoji Fernando Garcia-Escobar Tomoya Tashiro Hideki Abe* Keisuke Taka-hashi*H. Suzuki*, F. G. Escobar, T. Tashiro, K. Takahashi*AddressDepartment of Chemistry, Hokkaido University, North 10, West 8, Sapporo 060-0810, JapanEmail Addresssuzukihazime@eis.hokudai.ac.jpkeisuke.takahashi@sci.hokudai.ac.jpS. Shoji, H. Abe*AddressNational Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, JapanEmail Addressabe.hideki@nims.go.jpK. Takahashi*AddressInstitute for Chemical Reaction Design and Discovery, Hokkaido University, Kita 21, Nishi 10, Kita-ku,Sapporo, Hokkaido, 001-0021, Japan Email Addresskeisuke.takahashi@sci.hokudai.ac.jpKeywords: Gold Phosphide,Materials Synthesis, Density Functional Theory, Macroscopic CrystallineAmong transition metal phosphides, Gold phosphide (Au2P3) is particularly uncommon and lacks established synthesis methods forlarge-scale or structurally controlled materials, thus hindering its functional applications. This study introduces a synthetic strategyinvolving annealing gold mesh in red phosphorus vapor within a sealed quartz tube reactor, enabling a direct structural transforma-tion into crystalline Au2P3 while preserving macroscopic geometry. Comprehensive characterization using XRD, SEM, EDS, andXPS confirms successful formation, revealing covalent Au–P bonding and a semiconducting nature validated by density functionaltheory (DFT) simulations, which accurately predict lattice parameters and electronic properties. This method opens possibilities forpractical applications of Au2P3.1 IntroductionGold phosphides remain an underexplored class of compounds compared to their transition metal coun-terparts, despite gold’s distinct electronic structure and chemical inertness[1, 2, 3]. Among them, Au2P3is particularly rare, with limited reports focused primarily on crystallography and no established syn-thesis strategies for controlled morphology or large-scale structures. No functional applications have yetbeen demonstrated for Au2P3, largely due to challenges in synthesizing phase-pure material and inacces-sibility of defined geometries. Recent advances in phosphidation chemistry, especially involving red phos-phorus, have enabled the conversion of various metals into their corresponding phosphides[4, 5, 6]. How-ever, such methods typically produce nanoparticles, thin films, or powders, and have not been extendedto macroscale metallic substrates. Direct structural transformation of metallic gold into a crystallinegold phosphide structure with preserved macroscopic architecture has not been previously reported. Here,gold phosphorus is used to transform macroscopic gold mesh to Au2P3 method via gas flow reactor.2 Materials SynthesisAu2P3 mesh is synthesized by annealing Au mesh in phosphorus vapor. A quartz tube with an outer di-ameter of 15 mm, a wall thickness of 1 mm, and a length of 100 mm is selected as the growth container,which is dried in oven after cleaning. Red phosphorus (50 mg, RP, 99.9999%, FURUUCHI CHEMICAL),quartz cotton, and Au mesh (300 mg, 99.95%, THE NILACO CORPORATION) are put into a quartz1Figure 1: (a)Au mesh before reaction. (b)Gold phosphide (Au2P3) mesh in quartz tube. (c)XRD patterns of Au andAu2P3 mesh. Blue lines represent measured peaks and red lines represent simulated peaks.tube. After being sealed under a vacuum (<10 Pa) using rotary pump and turbo molecular pump, thequartz tube is put into the tube furnace. RP is located in the low-temperature zone of quartz tube, andAu mesh is in the high-temperature zone. The reactor is heated to 600 ◦C at a rate of 10 ◦C/min fromroom temperature to avoid cracking of the material and kept for 1 h of heat preservation at this temper-ature. The quartz tube after reaction is shown in Fig. 1(b). The black mesh is Au2P3 and red chunk iswhite phosphorus. Au2P3 mesh is taken from quartz tube and washed by water to remove white phos-phorus. The Au2P3 samples are extracted from the sealed quartz tubes under extra careful precautions.3 Result and DiscussionX-ray diffractometers (XRD, Rigaku, MiniFlex600), scanning electron microscope (SEM, Hitachi High-Tech, SU1510), and X-ray energy scattering spectroscope (EDS) are performed in order to analyze thesize, morphology, and composition of sample. The XRD pattern shows sample has Au2P3 peaks as shownin Fig. 1(c), which correspond to previous work[7]. SEM images are acquired using an accelerating volt-age of 20 kV under a vacuum of 30 Pa. The sample for SEM is coated by platinum to improve electronicconductivity. SEM image and EDS spectrum indicate that Au2P3 crystal size is ∼10 µm and the ratio ofP/Au is 1.26 as shown in Fig. 2(a).X-ray photoelectron spectroscopy (XPS, JEOL, JPS-9200) with a Mg-Kα X-ray source (10 mA, 10 kV)is performed in order to analyze the surface electron states of Au2P3 as shown in Fig. 2(e)(f). The resultindicates that the surface electron state of Au2P3 is characterized by Au 4f peaks at 83.4 eV and 87.1 eVand P 2p peaks at 128.7 eV and 133.5 eV. The Au peaks are shifted to lower binding energies relativeto metallic Au (∼ 84 eV for 4f7/2 and ∼ 88 eV for 4f5/2), suggesting covalent environment around theAu atoms[8]. Meanwhile, the primary P peak at 128.7 eV is comparable to the peak observed in typicalmetal phosphides (∼ 129 eV), and the higher-energy peak at 133.5 eV is attributed to surface-oxidation-induced phosphate species[8]. These observations imply that Au2P3 forms covalent bonds rather thanionic bonds.The density functional theory (DFT) calculation are confirmed through direct comparison with exper-imental measurements. The grid-based projector augmented wave software package (GPAW) within isimplemented[11]. The exchange–correlation of Perdew–Burke–Ernzerhof is implemented with spin polarization[12].Grid spacing is set to 0.20 Å and 4x4x4 special k points of the Brillouin zone sampling is applied [13].The relaxation procedure is executed until the forces on each atom are smaller than 0.10 eVÅ−1. Badercharge analysis is implemented to understand the charge transfer [14, 15]. Both DFT calculations andX-ray diffraction (XRD) analysis reveals matching lattice constants; the DFT-computed values are a =5.89 Å, b = 14.43 Å, c = 4.73Å, while experimental values are a = 5.86 Å, b = 14.43 Å, c = 4.67Å, in-dicating reliable reproduction of the crystal structure, as shown in Fig. 3(a). Moreover, X-ray diffraction2Figure 2: The SEM image and EDS spectrum of Au2P3. (a)SEM image of the Au2P3 mesh. (b)Element scanning mappingof Au element and (c)P element of Au2P3. (d)Element contents of Au and P in the sample. (e)(f)XPS patterns of Au 4fand P 2p orbitals of Au2P3.3Figure 3: (a)The illustration of Au2P3 structure. Atomic color code: yellow-gold, purple-phosphorus. (b)Projected densityof states (PDOS) between Au-d and P-p states. (c)The electronic band structure of Au2P3. Dot line indicates Fermi level.4patterns are simulated using visualization for electronic and structural analysis (VESTA)[16], as shownin Fig. 1(c). The result shows agreement with experimental data, reinforcing structural accuracy pre-dicted by the computational approach.Electronic structure analysis using Bader charge distribution and projected density of states (PDOS)further aligns with X-ray photoelectron spectroscopy (XPS) findings. The Bader analysis yields subtlecharge transfers of approximately +0.1e on phosphorus (P) atoms and -0.1e on gold (Au) atoms, indica-tive of a covalent bonding character. PDOS shows overlapping between Au-d and P-p states in the rangeof -1.1 to -0.4 eV, as shown in Fig. 3(b). The result supports the covalent bonding character, indicatingagreement with the Bader analysis and XPS measurements.The electronic band structure is demonstrated to understand a electronic nature of Au2P3, as shown inFig. 3(c). The result indicates an indirect band gap between the Γ and X points. The band gap is cal-culated to be 0.12 eV using PBE functional, while employing the GLLB-SC functional yields a band gapof 0.17 eV. Materials with an indirect band gap of 0.17 eV are ideally suited for mid-infrared photodetectors[9,10]. Futher modification such as doping could increase the conductivity of Au2P3. Thus, Au2P3 exhibitspromising semiconducting behavior with an indirect band gap.4 ConclusionIn conclusion, this work demonstrates the direct transformation of macroscopic gold mesh into crystallineAu2P3 by annealing in phosphorus vapor. It is noteworthy that the synthesized Au2P3 mesh retains itscrystalline structure even after several months of storage in air. The synthesized Au2P3 mesh exhibitscrystallinity and covalent bonding characteristics, validated experimentally via XRD, SEM, EDS, andXPS. DFT simulations complement these findings by precisely reproducing lattice parameters and pre-dicting an indirect semiconducting band gap, confirming the covalent bonding nature. This synthesisapproach significantly advances the material availability and practical use of Au2P3, overcoming histor-ical challenges related to producing structurally defined and phase-pure gold phosphide materials. Thecombination of experimental and theoretical analyses provides robust evidence supporting potential elec-tronic applications for Au2P3.AcknowledgementsThis work is funded by the Japan Science and Technology Agency(JST) ERATO grant number (JPM-JER1903), and JST Mirai Program Grant Number (JP-MJMI25G1), JSPS KAKENHI Grant in Aid forScientific Research (B) Grant Number (JP23H01762) and (24K01241), Grant-in-Aid for JSPS FellowsGrant Number (JP24KJ0272).ReferencesReferences[1] N. Panyala, J. Havel, Rapid Commun. Mass Spectrom. 2012, 26, 1100–1108.[2] S. Carenco, I. Florea, O. Ersen, New J. Chem. 2013, 37, 1231–1237.[3] D. Fernando, T. Nigro, I. Dyer, S. Alia, B. Pivovar, Y. Vasquez, J. Solid State Chem. 2016, 242,182–192.[4] K. Bhunia, M. Chandra, S. Sharma, D. Pradhan, S. Kim, Coord. Chem. Rev. 2023, 478, 214956.[5] L. He, J. Guo, S. Liu, F. Wang, X. Li, Z. Su, J. Alloys Compd. 2024, , 174924.[6] Z. Xing, Q. Liu, A. Asiri, X. Sun, ACS Catal. 2015, 5, 145–149.[7] W. Jeitschko, M. Moller, Acta crystallographica. Section B. 1979, 35, 573–579.[8] J. Rumble Jr, D. Bickham, C. Powell, Surf. Interface Anal. 1992, 19, 241–246.5REFERENCES[9] S. Hou, L. Han, S. Zhang, L. Zhang, K. Zhang, K. Xiao, Y. Yang, Y. Zhang, Y. Wen, W. Mo, Adv.Sci. 2025, 12, 2415518.[10] M. Chou, R. Bansal, Y. Jheng, G. Sun, W. Du, S. Yu, G. Chang, Adv. Photonics Res. 2025, 6,2400155.[11] J. Mortensen, L. Hansen, K. Jacobsen, Phys. Rev. B 2005, 71, 035109.[12] J. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 1996, 77, 3865.[13] H. Monkhorst, J. Pack, Phys. Rev. B. 1976, 13, 5188.[14] G. Henkelman, A. Arnaldsson, Comput. Mater. Sci. 2006, 36, 354–360.[15] W. Tang, E. Sanville, G. Henkelman, J. Phys.: Condens. Matter. 2009, 21, 084204.[16] K. Momma, F. Izumi, J. Appl. Crystallogr. 2011, 44, 1272–1276.Figure 4: Table of contents6