Photoelectrochemical Solar Water Splitting Research Articles

Surface wettability control of bubble flow guide for a thin aqueous electrolyte layer of solar photoelectrochemical reactors

Abstract Hydrogen is a promising energy carrier as no carbon dioxide is emitted during its use in fuel cells or combustion. Solar photoelectrochemical water splitting is a potential process for producing renewable hydrogen. Herein, energy transport phenomena are addressed for the future design of large-scale reactors. First, we show that the thickness of the aqueous electrolyte layer is an essential factor for utilizing the full spectrum of solar radiation. The transport of solar irradiation through the aqueous electrolyte is theoretically analysed. Next, based on the measurement of light transmission through hydrogen bubbles generated from a hydrogen evolving electrode, the energy loss caused by the bubbles covering a photoelectrode is discussed. The bubble size distributions at practical current densities are also presented. Then, a bubble flow guide for controlling the stream of bubbles in a thin electrolyte layer is proposed. A design strategy and experimental results verifying the performance of the bubble flow guide are presented. We demonstrate that surface wettability and inclination angle are important for designing an effective bubble flow guide. We examine the surface wettability control using hydrophilic coatings in detail. Changes in the water contact angles as well as bubble adhesion forces on the coated surfaces are demonstrated. In addition, the current experimental method can be used to identify essential issues in photoelectrochemical processes. Because bubble trapping and growth in a flow guide are reflected in the electrode potential variation, the discussion of electrode potential variation would be useful for further developing bubble flow guides. Overall, this study demonstrates the potential for developing and designing solar photoelectrochemical reactors.

Hydrogen bubble management in planarly confined aqueous electrolyte: Fundamental factors for scale-up reactor design

Solar photoelectrochemical water-splitting is a potential process for producing renewable hydrogen. Here, the energy transport phenomena associated with hydrogen bubble generation are investigated for the future design of large-scale reactors. Light transfer analysis shows that using a thin aqueous-electrolyte layer is essential for utilizing the full spectrum of solar radiation. The hydrogen bubble flow needs to be redirected to avoid screening the photoelectrode from incident light. Hence, a bubble flow guide for controlling the stream of bubbles in a planarly confined aqueous electrolyte has been proposed. It is found that the surface wettability and inclination angle are important for designing an effective bubble flow guide. The hydrophilic coating on a polymethyl methacrylate surface inhibits bubble adhesion and reduces energy loss. Furthermore, measuring the electrode potential variation during water electrolysis is useful for comparing the performances of bubble flow guides.

A Visible Light-Responsive TiO2 Photocathode Achieved by a Rh Dopant.

Developing an efficient and stable photocathode material for photoelectrochemical solar water splitting remains challenging. Herein, we demonstrate the potential of rutile TiO2 as a photocathode by Rh doping with visible light absorption up to 640 nm and an onset potential of 0.9 V versus the reversible hydrogen electrode. The dopant transforms the rutile host from an n-type semiconductor to a p-type one, as confirmed by the Mott-Schottky curve and kelvin probe force microscopy. Physical and photoelectrochemical analyses further suggest that the doping mechanism is dependent on concentration. Lower levels of dopants generate localized Rh3+, while higher levels favor Rh4+ that interacts more strongly with the O 2p orbitals. The latter is found not only to extend the visible light absorption range but also to facilitate charge transport. This work elucidates the role of the Rh dopant in adjusting the photoelectrochemical behavior of TiO2, and it provides a promising photocathode material for solar energy conversion.

Tailoring multi-layered BiVO4/WO3 photoanodes for an efficient photoelectrochemical gas-phase solar water splitting

Photoelectrochemical gas-phase solar water splitting represents a promising avenue for sustainable hydrogen production, fulfilling the energy demands of the future. In this work, we present the fabrication and optimization of the functional performance of visible-light active BiVO4/WO3 photoanodes with a tailored multi-layered structure. The photoanodes are manufactured in a reproducible way by an automated spray pyrolysis technique, including BiVO4 (top layer) and WO3 (bottom layer) in a multi-layered structure with different ratios (80:20; 50:50; 20:80). The photoactive surfaces are fully characterized and then evaluated in a divided filter-press reactor operated in continuous mode under visible light irradiation (100 mW cm−2), where a platinized titanium plate is used as dark cathode. The results demonstrate the pivotal role of mass ratio in optimizing charge transfer kinetics and recombination rates in the photoanode. We demonstrate the synergistic effects between BiVO4 and WO3, elucidating their contributions to enhance light absorption, and reduce electron-hole recombination, determining an optimal ratio of 80:20 for both hydrogen production (155.7 μmol m−2 s−1) and on-off current density gap (0.66 mA cm−2). The developed multi-layered BiVO4/WO3 surfaces thus offer a compelling pathway for advancing gas-phase photoelectrochemical water splitting technology, underscoring the significance of electrode design and paving the way for sustainable solar hydrogen production.

Transition Metal Doped BiVO4 Photoanodes: A Mechanistic Study

BiVO4 has emerged as one of the most promising materials to fabricate efficient photoanodes for photoelectrochemical (PEC) solar water splitting. BiVO4 is an n-type semiconductor, with a 2.4 eV bandgap and a theoretical solar to hydrogen (STH) efficiency of 9.2% with a maximum photocurrent of 7.5 mA cm2 under AM 1.5 G illumination, low overpotential and favourable band-edge positions towards the Oxygen Evolution Reaction (OER).1 However, BiVO4 also presents poor electron transport, high surface recombination and slow water oxidation kinetics. Hence, enormous efforts have been made in the past few years to mitigate these drawbacks through different approaches such as nanostructuring,2 doping,3 heterostructuring,4 and the use of efficient co-catalysts.5 The present study proposes a transition metal doping (Ni, Fe and Co) of BiVO4 photoelectrodes that boosts their water oxidation performance. The origin of this enhanced performance towards Oxygen Evolution Reaction (OER) was studied by a combination of a suite of structural, chemical, and mechanistic advanced characterization techniques including X-Ray Photocurrent Spectroscopy, Electrochemical Impedance Spectroscopy and Transient Absorption Spectroscopy, among others.[1] J. Li and N. Wu, Catal. Sci. Technol., 2015, 5, 1360–1384.[2] S. P. Berglund, D. W. Flaherty, N. T. Hahn, A. J. Bard and C. B. Mullins, J. Phys. Chem. C, 2011, 115, 3794–3802.[3] S. K. Pilli, T. E. Furtak, L. D. Brown, T. G. Deutsch, J. A. Turner and A. M. Herring, Energy Environ. Sci., 2011, 4, 5028–5034.[4] J. Su, L. Guo, N. Bao and C. A. Grimes, Nano Lett., 2011, 11, 1928–1933.[5] D. K. Lee and K.-S. Choi, Nat. Energy, 2018, 3, 53–60.

G-C3N4/La2O3 nanocomposite as a photo-electrocatalyst in solar water splitting

The enhancement of g-C3N4 photocatalytic performance is most effectively achieved through doping or composite incorporation. Notably, rare-earth element nanocomposites, characterized by their exclusive 4f electronic configuration, have demonstrated remarkable potential in boosting photocurrent density. In this study, we successfully prepared a Lanthanum (La)-incorporated g-C3N4 composite using the methanolic dispersion method, resulting in a photostable photoanode. The optimized g-C3N4 composite, featuring approximately ∼59.8 % La composition, exhibited a substantial photocurrent of approximately ∼10.16 μA cm−2, a significant improvement compared to the unaltered g-C3N4, which only achieved about 4.56 μA cm−2 at 1.23 vs. Ag/AgCl. The introduction of lanthanum into the composite modified the elemental composition by introducing oxygen-doping into the g-C3N4 structure. Additionally, the unique dual nanostructures, comprising nanoparticles and nanoflakes, played a crucial role in enhancing catalytic sites, increasing surface area, and improving light absorption. According to the BET analysis, the N2 adsorption–desorption isotherms reveal that the SBET of g-C3N4/la2O3–59.8 % is approximately 74.84 m2 g−1, surpassing the surface area of pristine g-C3N4, which is approximately 65.32 m2 g−1. Moreover, the formation of the nanocomposite contributed to a reduction in the band gap from 2.82 eV (pure g-C3N4) to 2.74 eV (g-C3N4/La-59.8 %). In conclusion, due to its exceptional photostability and remarkable performance, the g-C3N4/La2O3 nanocomposite exhibits significant promise as a potential candidate in the field of photocatalysis, with prospective applications in Photoelectrochemical (PEC) solar water splitting.

Conductive Passivator and Dipole Layer Mixture Enabling High‐Performance Stable Perovskite Photoelectrode‐Based Solar Water Splitting

AbstractRecently, lead halide perovskites have attracted significant attention as promising absorber materials for photoelectrochemical (PEC) solar water splitting. However, charge‐accumulation‐induced ion migration at the interface causes perovskite degradation and efficiency loss. To suppress the charge accumulation and improve the PEC performance of the perovskite photoanode, a simple interface engineering is proposed by decorating the SnO2/perovskite interface with a mixture of polyethylenimine ethoxylated (PEIE) and chlorobenzenesulfonic acid (CBSA). The mixed CBSA+PEIE treatment effectively passivates the oxygen vacancies in SnO2 and adjusts the band alignment between SnO2 and the perovskite. The synergistic effects of the mixture treatment facilitate an effective carrier extraction at the SnO2/perovskite interface, enhance the PEC performance, and improve the stability of the device. The perovskite photoanode exhibits an impressive applied bias photon‐to‐current efficiency of 12.9% with an outstanding durability for 225 h. Furthermore, an unbiased solar water splitting is achieved using all the perovskite photoelectrodes, resulting in a remarkable unassisted solar‐to‐hydrogen efficiency of 10.9% and a continuous 22 h stable operation.

Carrier Localization on the Nanometer‐Scale limits Transport in Metal Oxide Photoabsorbers

AbstractMetal oxides are considered as stable and low‐cost photoelectrode candidates for hydrogen production by photoelectrochemical solar water splitting. However, their power conversion efficiencies usually suffer from poor transport of photogenerated charge carriers, which has been attributed previously to a variety of effects occurring on different time and length scales. In search for common understanding and for a better photo‐conducting metal oxide photoabsorber, CuFeO2, α‐SnWO4, BaSnO3, FeVO4, CuBi2O4, α‐Fe2O3, and BiVO4 are compared. Their kinetics of thermalization, trapping, localization, and recombination are monitored continuously 100 fs–100 µs and mobilities are determined for different probing lengths by combined time‐resolved terahertz and microwave spectroscopy. As common issue, we find small mobilities < 3 cm2V‐1s‐1. Partial carrier localization further slows carrier diffusion beyond localization lengths of 1–6 nm and explains the extraordinarily long conductivity tails, which should not be taken as a sign of long diffusion lengths. For CuFeO2, the localization is attributed to electrostatic barriers that enclose the crystallographic domains. The most promising novel material is BaSnO3, which exhibits the highest mobility after reducing carrier localization by annealing in H2. Such overcoming of carrier localization should be an objective of future efforts to enhance charge transport in metal oxides.

Photoelectrochemical Performance of Strontium Titanium Oxynitride Photo-Activated with Cobalt Phosphate Nanoparticles for Oxidation of Alkaline Water.

Photoelectrochemical (PEC) solar water splitting is favourable for transforming solar energy into sustainable hydrogen fuel using semiconductor electrodes. Perovskite-type oxynitrides are attractive photocatalysts for this application due to their visible light absorption features and stability. Herein, strontium titanium oxynitride (STON) containing anion vacancies of SrTi(O,N)3-δ was prepared via solid phase synthesis and assembled as a photoelectrode by electrophoretic deposition, and their morphological and optical properties and PEC performance for alkaline water oxidation are investigated. Further, cobalt-phosphate (CoPi)-based co-catalyst was photo-deposited over the surface of the STON electrode to boost the PEC efficiency. A photocurrent density of ~138 μA/cm at 1.25 V versus RHE was achieved for CoPi/STON electrodes in presence of a sulfite hole scavenger which is approximately a four-fold enhancement compared to the pristine electrode. The observed PEC enrichment is mainly due to the improved kinetics of oxygen evolution because of the CoPi co-catalyst and the reduced surface recombination of the photogenerated carriers. Moreover, the CoPi modification over perovskite-type oxynitrides provides a new dimension for developing efficient and highly stable photoanodes in solar-assisted water-splitting reactions.

Ferroelectric polarization controlled surface potential and charge transport across ITO-Nd-doped BiFeO3 polycrystalline ceramic bulk for photoelectrochemical solar water splitting

The spontaneous polarization in ferroelectrics provides an effective way to engineer interfacial charge distribution at the ferroelectric heterojunctions, thereby depletion width in p-n junction and energy band structures. Here, we integrated p-type multiferroic 7% neodymium-doped bismuth ferrite Bi0.93Nd0.07FeO3 (BFO7Nd) polycrystalline ceramic bulk with n-type transparent conductive indium tin oxide (ITO) to demonstrate the influence of ferroelectric polarization on surface potential and its effect on photoelectrochemical (PEC) water reduction. Kelvin probe force microscopy (KPFM) results reveal the surface potential change during ferroelectric polarization switching, suggesting that the polarization bound charges may have an effect on space charge region between ITO-BFO7Nd, thus dominating surface potential at the electrode/electrolyte interface. This implies that the interface barrier between ITO and BFO7Nd can be easily modulated by polarization bound charges. The electron lifetime of upward-polarization (P-up) ITO-BFO7Nd is estimated 29.30 ms, about 15 times longer than unpoled ITO-BFO7Nd. The photocurrent density of P-up ITO-BFO7Nd is ∼1.2 × 10−6 A/cm2 (at 0 V vs RHE), which is one-order higher compared to that of the unpoled and P-down states under illumination with an intensity of 100 mWcm−2. This work shows that ferroelectric polarization combined with photogenerated carriers is an effective approach for effective charge transfer in multiferroic ceramic to boost PEC solar water splitting.

Formation of photo-reactive heterostructure from a multicomponent amorphous alloy with atomically random distribution

• The alloy design and simple process are based on unique properties of the atomically random distribution. • The TiCuNiSn was designed to form a functional oxide with the capability for water splitting. • The TiCuNiSn was fabricated multi-layered functional structures using one-step process. • Each layer exhibits different functional roles and is formed with a systematic and stable structure. • Metallic glass shows a new possibility for PEC cells applied to both the photoanode and photocathode for water splitting. In this study, metallic glass is designed tunable for promising functional applications via a facile and stable, one-step process. Creative approach about alloy design and process is based on the unique properties of the Ti-Cu-Ni-Sn metallic glass that are afforded by the varying oxygen affinities of the four constituent elements. This metallic glass exhibits homogeneous nucleation of oxides and uniform formation of the various metal oxides. The alloy design and hydrothermal synthesis to customize the metallic glasses are the most critical factors that determine the characteristics of the metal oxides and the resulting nanostructures and photoelectrode properties. This enables the desired element to be selectively grown via a facile single-step process. These results provide a promising road map for the application of metallic glasses to photoelectrochemical (PEC) solar water splitting, as well as various other new possibilities.

Synergistic defect- and interfacial-engineering of a Bi2S3-based nanoplate network for high-performance photoelectrochemical solar water splitting

Successful modulation of photoelectrochemical performance of Bi2S3 nanowalls was achieved by a synergistic defect- and interface-engineering strategy, which renders significantly improved charge separation and transfer efficiency in water splitting.

Crystal Facet‐Controlled Efficient SnS Photocathodes for High Performance Bias‐Free Solar Water Splitting (Adv. Sci. 21/2021)

Photoelectrochemical Solar Water Splitting In article number 2102458 by Ho Won Jang, Jooho Moon, and co workers, performance bias-free solar water splitting is reported. Sulfur precursor with a weak dipole moment produces high-quality dense SnS nanoplates with enlarged favorable crystallographic facets, suppressing anisotropic growth. Ga2O3 interlayered SnS photocathode efficiently improves charge transport kinetics without charge trapping. The high-performance SnS photocathode represents a promising platform for photoelectrochemical solar water splitting.

Novel edge-capped ZrO2 nanoparticles onto V2O5 nanowires for efficient photosensitized reduction of chromium (Cr (VI)), photoelectrochemical solar water splitting, and electrochemical energy storage applications

Novel edge-capped ZrO2 nanoparticles on V2O5 nanowires were successfully synthesized through a simple, eco-friendly, and inexpensive hydrothermal technique. The as-prepared nanostructures were characterized using various measurements to study their structural, morphological, optical, and surface properties. Furthermore, photoelectrochemical water oxidation, photocatalytic performance for Cr(VI) reduction, and electrochemical energy storage were studied. The surface morphology analysis revealed the edge-capped ZrO2 nanoparticles on the V2O5 nanowires. The optical analysis showed that the heterostructure formation between ZrO2 and V2O5 could tune the bandgap (2.05 eV) of the composite. Due to the improved separation efficacy of the photoexcited charge carriers and greater surface area, compared to the pure materials, the ZrO2/V2O5 (ZV) composite displayed considerable improvement in photocatalytic Cr(VI) reduction performance, as well as excellent reusability performance (70.5 % after 4 cycles), thus facilitating its wastewater treatment. The ZV electrode displayed approximately 1.6- and 5.8-fold improvement in specific capacitance over the ZrO2 and V2O5 electrodes, respectively. Furthermore, the ZV electrode exhibited the lowest charge resistance under light illumination conditions. From the linear sweep voltammetry curve analysis, the ZV electrode possessed an improved photocurrent density (5.363 mA cm−2), demonstrating approximately 33- and 3.5-times improvement in photocurrent density over the pristine electrodes.

Crystal Facet-Controlled Efficient SnS Photocathodes for High Performance Bias-Free Solar Water Splitting.

To achieve a high solar‐to‐hydrogen (STH) conversion efficiency, delicate strategies toward high photocurrent together with sufficient onset potential should be developed. Herein, an SnS semiconductor is reported as a high‐performance photocathode. Use of proper sulfur precursor having weak dipole moment allows to obtain high‐quality dense SnS nanoplates with enlarged favorable crystallographic facet, while suppressing inevitable anisotropic growth. Furthermore, the introducing Ga2O3 layer between SnS and TiO2 in SnS photocathodes efficiently improves the charge transport kinetics without charge trapping. The SnS photocathode reveals the highest photocurrent density of 28 mA cm−2 at 0 V versus the reversible hydrogen electrode. Overall solar water splitting is demonstrated for the first time by combining the optimized SnS photocathode with a Mo:BiVO4 photoanode, achieving a STH efficiency of 1.7% and long‐term stability of 24 h. High performance and low‐cost SnS photocathode represent a promising new material in the field of photoelectrochemical solar water splitting.

A novel photoanode based on Thorium oxide (ThO2) incorporated with graphitic Carbon nitride (g-C3N4) for Photoelectrochemical water splitting

In this study, a new insight into the doping engineering with nuclear fuel (ThO2) was performed and applied in photoelectrochemical (PEC) water splitting. The successfully synthesized g-C3N4/ThO2 (~5.8%) via thermal treatment and g-C3N4 polymerization (precursor: Urea, 30 min; 520 ˚C) manifested a remarkable and superior photocatalytic activity. The photocurrent density achieved for g-C3N4/ThO2 was 9.71 μcm−2 at 1.23 V vs. Ag/AgCl under simulated light (100 mW/cm2) that is more than twice compared with the un-doped g-C3N4 (~4.23 μA cm−2). The introduction of Thorium Nitrate during g-C3N4 polymerization altered the chemical bonding, structure, and morphology, with the improved PEC stability of the photoanode. Besides, doping with ThO2 increased the intensity of triazine and C-N bond in the g-C3N4 network, as observed by FT-IR analysis. The unique “hollow cylindrical” architecture also increased the surface area, light absorption, as well as the catalytic sites. The enhanced separation of photo-generated electron–hole pairs reduced the carrier recombination that was obviously probed via Photoluminescence spectra. Therefore, due to the photostability and the good performance, the g-C3N4/ThO2 composite can be envisioned as a potential candidate in the field of photocatalysis and prospectively be applied in PEC solar water splitting.

Novel TiO2/Bi4Ti3O12 nanorod arrays decorated with Co-Pi for boosted solar photoelectrochemical water splitting

We present a simple methodology to construct novel Co-Pi decorated TiO 2 /Bi 4 Ti 3 O 12 nanorod (TiO 2 /BTO@Co-Pi NR) arrays as photoanode for enhanced water splitting. By using successive ionic layer adsorption and reaction (SILAR) method, controllable amounts of BiOI nanoplates were uniformly immobilized on the hydrothermal grown TiO 2 NR arrays on Fluorine-doped tin oxide (FTO) substrate. TiO 2 /BTO NR heterojunction was conveniently obtained by partial conversion of TiO 2 to high crystallized Bi 4 Ti 3 O 12 through a solid-state reaction with BiOI nanoplates at high temperature. Afterwards, Co-Pi nanoparticles were deposited on TiO 2 /BTO by photoelectrical deposition to generate TiO 2 /BTO@Co-Pi composites. Photoelectrochemical (PEC) measurements have demonstrated that the prepared TiO 2 /BTO photoanode exhibits extremely enhanced performance than pristine TiO 2 for PEC water splitting thanks to the increased visible light absorption and photogenerated charge separation efficiency. Moreover, both the photocurrent density and incident photo-to-current conversion efficiency (IPCE) were further improved after the decoration of Co-Pi. This work provides a feasible and low-cost strategy to establish TiO 2 /Bi 4 Ti 3 O 12 based photoelectrode, therefore, is suitable for practical applications. • Novel TiO 2 /Bi 4 Ti 3 O 12 nanorod arrays were easily constructed by simple SILAR and solid-state reaction. • Controllable Bi 4 Ti 3 O 12 could be formed by adjusting the SILAR cycles to achieve a optimium photocurrent. • BTO can largely enhance the IPCE and photocurrent density, which were further improved by Co-Pi nanoparticles.

Effect of noble metal ions dopants on solar photoelectrochemical water splitting and electrochemical supercapacitive performance of BiVO4 hollow tubes

Owing to their poor electrochemical properties, photoelectrochemical (PEC) solar water splitting and electrochemical energy storage activity of BiVO4 are presently limited in their applications. One of the effective methods for improving electrochemical activity is the doping of noble-metal ions into the host lattice. The doping of noble-metal ions can improve absorption in visible light and support the direct transfer of energy via hot electrons. In this study, the synthesis of Au-doped BiVO4 nanostructured catalysts with different concentrations of Au ions was prepared via a template-free ultrasonication technique, and it's both solar-driven PEC water splitting and electrochemical storage properties were examined. The optimal doped photoelectrode exhibited a lower resistance to charge transfer than other photoelectrodes, including a significant enhancement in photocurrent density (0.102 mAcm−2), which is approximately 4.1 times superior over undoped photoanode. Furthermore, the optimal doped electrode exhibited an electrochemical capacitance that is 2 times greater than that of the pure electrode. The excellent electrochemical behavior and PEC properties of the optimal doped electrode were attributed to the increase in surface area and suitable band gap. Consequently, enables the dispersion of electron at the interface of electrode/electrolyte. Solar PEC solar water splitting and supercapacitor performance of the optimal doped electrodes were significantly improved by the proper incorporation of Au ions.

Passivation of ZnSe nanoparticles in sandwiched CdSe/ZnSe/ZnO nanotube array photoanode to substantially enhance solar photoelectrochemical water splitting for hydrogen evolution

By integrating ZnSe passivation nanoparticles into a binary heterostructure via a facile consecutive ion-replacement reaction method, we demonstrate a solar-light-driven CdSe/ZnSe/ZnO sandwich nanotube array photoanode for hydrogen evolution via a photoelectrochemical cell. The constructed CdSe/ZnSe/ZnO sandwich nanotube array photoanode displays drastically boosted photoelectrochemical ability to generate hydrogen. The hydrogen production rate of the CdSe/ZnSe/ZnO sandwich nanotube array photoanode reaches up to 54.4 μmol h−1, which is around 5 and 6 times that of the ZnSe/ZnO and ZnO nanotube array photoanodes, respectively. Moreover, the photoconversion efficiency of the CdSe/ZnSe/ZnO sandwich nanotube array photoanode reaches up to 1.7 % at 0.5 V versus RHE, which is 34 and 24 times that of the ZnO and ZnSe/ZnO nanotube array photoanodes, respectively. The measurements of the electrochemical properties demonstrate that the drastically enhanced PEC water splitting for hydrogen evolution of the sandwiched CdSe/ZnSe/ZnO nanotube arrays is attributed to the efficient separation of the photogenerated charge carriers.

Au-doped BiVO4 nanostructure-based photoanode with enhanced photoelectrochemical solar water splitting and electrochemical energy storage ability

BiVO4 is an appropriate photoanode material for solar-powered photoelectrochemical (PEC) water splitting and electrochemical energy storage. However, it has a few drawbacks. Therefore, doping with noble metals is speculated to be a promising technique to overcome these. Moreover, the role of the doped noble metal in the improvement of the water oxidation kinetics and energy storage has not been studied adequately so far. In this study, we prepared Au-doped BiVO4 nanostructures using a simple template-free ultrasonication technique. The effect of Au doping on the optical properties and surface morphology of the BiVO4 nanostructures, and their performance as a photoanode for energy harvesting are explored comprehensively. The 5Au- BiVO4 photoelectrode displayed a considerable improvement (~29 times) in the PEC photocurrent density compared to that of the pure BiVO4 photoanode. Electrochemical impedance spectroscopy studies confirmed that the dopant improved the charge carrier density and acted as an electron donor. Furthermore, it was confirmed that the photocurrent density at 1.23 V vs. the reversible hydrogen electrode increased after Au doping. The supercapacitor properties of the 5Au-BiVO4 electrode were studied by cyclic voltammetry. At a 10 mV s−1 scan rate, the specific capacitance of the 5Au-BV electrode increased to ~2.1 times that of the pure electrode. The significantly improved PEC performance and supercapacitor properties of the 5Au-BiVO4 electrode are attributed to its higher conductivity, improved interfacial charge transfer at the surface of BiVO4, and the synergistic effect between the host and dopant.