High-efficiency solar-to-hydrogen conversion via MoS₂-enhanced GaAs heterojunctions for efficient photoelectrochemical water splitting

Abstract

Gallium arsenide (GaAs) heterojunctions have been widely explored for their promising applications in solar cells (SCs) and photoelectrochemical (PEC) water splitting, owing to their cost-effective design and great potential for enhancing power conversion efficiency (PCE). In this study, an innovative MoS₂ hole-transport layer was introduced into the GaAs heterojunction for applications in SCs and PEC water splitting. By optimizing the thickness of the MoS₂ film, the sulfide oxidation reaction at the heterointerface was effectively suppressed. Significantly, a synergistic system integrating a GaAs heterojunction SC with a photoelectrode was proposed. The incorporation of carbon nanotubes into the GaAs/MoS₂ heterojunction significantly improved charge carrier transport, enhancing the PCE from 0.24% to 12.41%. In the PEC water splitting system, the GaAs/MoS₂ heterostructure also demonstrated excellent oxygen evolution reaction performance. This optimization led to a maximum applied bias photon-to-current efficiency of 35% under bias, reaching 20% at 0 V vs. reversible hydrogen electrode (RHE), along with a photocurrent density of 40 mA cm^-2 and a solar-to-hydrogen conversion efficiency of 17.22%. When integrated into a photovoltaic-PEC system, the GaAs/MoS₂ photoelectrode achieved a current density of 20 mA cm^-2 at 0 V vs. RHE, with a 400 mV negative shift in the water oxidation onset potential, enabling highly efficient solar-driven hydrogen production.

Keywords

GaAs / MoS₂ / heterojunction / solar-to-hydrogen / water splitting

References

[1] Zhao Y,Zhao J,Fu X.Recent advancements in photoelectrochemical water splitting for hydrogen production.Electrochem Energy Rev2023;6:14

[2] Dong Z,Qin D.Recent advances and perspective of modified TiO₂-based photoanodes toward photoelectrochemical water splitting.Fuel2024;373:132366

[3] Su Y,Liao L.Unveiling the synergy of interfacial contact and defects in α-Fe₂O₃ for enhanced photo-electrochemical water splitting.Adv Funct Mater2023;33:2303976

[4] Gonçalves S,Freitas J.Unveiling morphology-structure interplay on hydrothermal WO₃ nanoplatelets for photoelectrochemical solar water splitting.ACS Appl Mater Interfaces2024;16:64389-409

[5] Gaikwad MA,Ghorpade UV,Suryawanshi MP.Emerging surface, bulk, and interface engineering strategies on BiVO₄ for photoelectrochemical water splitting.Small2022;18:2105084

[6] Das A,Banerjee N.High aspect ratio ZnO nanorods for improved photoelectrochemical (PEC) water splitting performances and efficient photocatalytic hydrogen evolution: an integrated experimental and DFT studies.Appl Surf Sci2025;699:163160

[7] Fu J,Nakabayashi M.Interface engineering of Ta₃N₅ thin film photoanode for highly efficient photoelectrochemical water splitting.Nat Commun2022;13:729 PMCID:PMC8821563

[8] Hojamberdiev M,Zhang F,Lerch M.Perovskite BaTaO₂N: from materials synthesis to solar water splitting.Adv Sci2023;10:2305179 PMCID:PMC10667847

[9] Shabbir SA,Haris M.Bifunctional Co₃O₄/g-C₃N₄ hetrostructures for photoelectrochemical water splitting.ACS Omega2024;9:21450-8

[10] Teitsworth TS,Litvin SR.Water splitting with silicon p-i-n superlattices suspended in solution.Nature2023;614:270-4

[11] Wang T,Liu Y.Construction of Z-type In₂O₃@InP heterostructure with enhanced photo-assisted electrocatalytic water splitting for hydrogen production.Int J Hydrogen Energy2024;64:166-77

[12] Alotaibi AM,Al Abass N.Surface engineering of CuO-Cu₂O heterojunction thin films for improved photoelectrochemical water splitting.Renew Energy2024;235:121326

[13] Cai Y,Liu B.Semi-transparent and stable In₂S₃/CdTe heterojunction photoanodes for unbiased photoelectrochemical water splitting.Nat Commun2025;16:5105 PMCID:PMC12130235

[14] Štěpánek J,Paušová Š.Two-step synthesis and characterization of CuFeO₂ thin layers for photoelectrocatalytic applications.Electrochimica Acta2025;535:146516

[15] Wang Z,Tu W.Host/guest nanostructured photoanodes integrated with targeted enhancement strategies for photoelectrochemical water splitting.Adv Sci2022;9:2103744 PMCID:PMC8805576

[16] Kang J,Lee J,Chaule S.Meso-pore generating P doping for efficient photoelectrochemical water splitting.Nano Energy2023;107:108090

[17] Yuan H,Su Y.A novel BiVO₄/DLC heterojunction for efficient photoelectrochemical water splitting.Chem Eng J2023;459:141637

[18] Li C,Jia X,Du B.Unveiling the influence of lower-valence Ni in hydroxide Co-catalyst and attaining efficient photoanodes with FeOOH holes transfer layer for photoelectrochemical water splitting.Adv Funct Mater2025;35:2406999

[19] Mo Y,Liu P,Wang W.Insights into the application of carbon materials in heterojunction solar cells.Mater Sci Eng R Rep2023;152:100711

[20] Zhang X,Ning X.Boron substitution enhanced activity of B_xGa_1-xAs/GaAs photocatalyst for water splitting.Appl Catal B Environ2022;300:120690

[21] Kang D,Lim H.Printed assemblies of GaAs photoelectrodes with decoupled optical and reactive interfaces for unassisted solar water splitting.Nat Energy2017;2:17043

[22] Vu TK, Tran MT, Kim EK. Optimization of active antireflection ZnO films for p-GaAs-based heterojunction solar cells.J Alloys Compd2022;924:166531

[23] Wang J,Liang J.InP QDs modified GaAs/PEDOT:PSS hybrid solar cell with efficiency over 15%.Nano Lett2024;24:12111-7

[24] Lin S,Wang P.Interface designed MoS₂/GaAs heterostructure solar cell with sandwich stacked hexagonal boron nitride.Sci Rep2015;5:15103 PMCID:PMC4602223

[25] Haggren T,Haggren A,Jagadish C.CuI as a hole-selective contact for GaAs solar cells.ACS Appl Mater Interfaces2022;14:52918-26

[26] Wen L,Yu Y.Enhancing the photovoltaic performance of GaAs/graphene Schottky junction solar cells by interfacial modification with self assembled alkyl thiol monolayer.J Mater Chem A2018;6:17361-70

[27] Li X,Zhang S.18.5% efficient graphene/GaAs van der Waals heterostructure solar cell.Nano Energy2015;16:310-9

[28] Chen Y,Zhou D.Highly efficient SWCNT/GaAs van der Waals heterojunction solar cells enhanced by Nafion doping.J Alloys Compd2023;932:167624

[29] Tan X,Qian G,Xie Q.The GaAs/InS vdW heterostructure shows great potential as a solar-driven water splitting photocatalyst.Mater Sci Semicond Process2023;167:107779

[30] Arunachalam M,Zhu K.Reliable bi-functional nickel-phosphate/TiO₂ integration enables stable n-GaAs photoanode for water oxidation under alkaline condition.Nat Commun2023;14:5429 PMCID:PMC10480475

[31] Mo Y,Huang T.Self-integrated carbon nanotube/graphene oxide-based GaAs heterojunction synergistically achieve unassisted water splitting with solar-to-hydrogen efficiency over 15%.Chem Eng J2025;519:164889

[32] Mo Y,Wang W.Interface passivation treatment enables GaAs/CNT heterojunction solar cells over 19 % efficiency.Nano Energy2024;131:110247

[33] Xia Y,Wei J.12-inch growth of uniform MoS₂ monolayer for integrated circuit manufacture.Nat Mater2023;22:1324-31

[34] Zhu Z,Leow WR.Approaching the lithiation limit of MoS₂ while maintaining its layered crystalline structure to improve lithium storage.Angew Chem Int Ed2019;58:3521-6

[35] Mouri S,Matsuda K.Tunable photoluminescence of monolayer MoS₂ via chemical doping.Nano Lett2013;13:5944-8

[36] Benoist L.XPS analysis of oxido-reduction mechanisms during lithium intercalation in amorphous molybdenum oxysulfide thin films.Solid State Ionics1995;76:81-9

[37] Zhang Y,Zhong B.Synthesis of higher alcohols from syngas over ultrafine Mo-Co-K catalysts.Catal Lett2001;76:249-53

[38] Tsuboi Y,Kozawa D.Enhanced photovoltaic performances of graphene/Si solar cells by insertion of a MoS₂ thin film.Nanoscale2015;7:14476-82

[39] Mak KF,Hone J,Heinz TF.Atomically thin MoS₂: a new direct-gap semiconductor.Phys Rev Lett2010;105:136805

[40] Frey GL,Homyonfer M,Tenne R.Optical-absorption spectra of inorganic fullerenelike MS₂ ( M=Mo, W).Phys Rev B1998;57:6666

[41] Komesu T,Ma Q.Symmetry-resolved surface-derived electronic structure of MoS₂(0 0 0 1).J Phys Condens Matter2014;26:455501

[42] Zhao C,Xie S.DFT study of electronic structure and properties of N, Si and Pd-doped carbon nanotubes.Ceram Int2018;44:21027-33

[43] Lee GH,Kim YD.Highly stable, dual-gated MoS₂ transistors encapsulated by hexagonal boron nitride with gate-controllable contact, resistance, and threshold voltage.ACS Nano2015;9:7019-26

[44] Ding K,Ning L.Hue tunable, high color saturation and high-efficiency graphene/silicon heterojunction solar cells with MgF₂/ZnS double anti-reflection layer.Nano Energy2018;46:257-65

[45] Abbasian S.Optimum design of ARC-less InGaP/GaAs DJ solar cell with hetero tunnel junction.J Electron Mater2018;47:3585-95

[46] Hemani A,Nouri A,Dekkich B.Effect of the FSF and BSF layers on the performances of the GaAs solar cell.J Ovonic Res2017;13:307-14https://chalcogen.ro/307_AbderrahmaneH.pdf (accessed 2025-11-24)

[47] Siavash Moakhar R,Masudy-Panah S.Photoelectrochemical water-splitting using CuO-based electrodes for hydrogen production: a review.Adv Mater2021;33:2007285

[48] Chen W,Tu C.Point defects in dilute nitride III-N-As and III-N-P.Phy B Condens Matter2006;376-7:545-51

[49] Meng X,Liu Y.Enabling unassisted solar water splitting with concurrent high efficiency and stability by robust earth-abundant bifunctional electrocatalysts.Nano Energy2023;109:108296

[50] Butson JD,Chen H.Surface-structured cocatalyst foils unraveling a pathway to high-performance solar water splitting.Adv Energy Mater2022;12:2102752

[51] Sun K,Chen Y,Lewis NS.A stabilized, intrinsically safe, 10% efficient, solar-driven water-splitting cell incorporating earth-abundant electrocatalysts with steady-state pH gradients and product separation enabled by a bipolar membrane.Adv Energy Mater2016;6:1600379

[52] Ben-naim M,Aldridge CW.Addressing the stability gap in photoelectrochemistry: molybdenum disulfide protective catalysts for tandem III-V unassisted solar water splitting.ACS Energy Lett2020;5:2631-40