Photoelectrochemical Catalysts Research Articles

Homo-Nuclear Hetero-Atomic Conjugated Reticular Oligomers for Heterojunction: A Novel "Electron Medium" for Panel Photoelectrocatalysis.

A substantial challenge in employing covalent organic frameworks (COFs) for photoelectrochemical (PEC) water splitting lies in improving their solution-processability while concurrently facilitating the transfer of charges and mass to the catalytic sites. Herein, we synthesize a solution-processable conjugated reticular oligomers (CROs), and further embed ruthenium (Ru) into the CRO, forming a CRO-Ru with homo-nuclear hetero-atomic. Thereafter, CRO and CRO-Ru construct an organic-organic heterojunction membrane at the nanoscale. Thisdesign achieves perfect lattice matching, significantly reducing the energy barrier of mass transfer, and effectively lowering the recombination rate of charge carriers. The optimized photocathode, CuI/CRO-Bpy:CRO-Bpy-Ru-1:1+P3HT/SnO2/Pt, exhibits an efficiency of 111.0µAcm-2 at 0.4V versus a reversible hydrogen electrode (RHE). Compared with the original bulk COFs and CROs, the efficiency is significantly improved. The apparent improvements in charge carrier separation and transfer are responsible for the high PEC activity. In the heterojunction, the incorporation of CRO-Bpy-Ru with a longer excited-state lifetime and a substantial built-in electric field has effectively accelerated the photo-induced electron transfer from the conduction band (CB) of CRO-Bpy to the valence band (VB) of CRO-Bpy-Ru, effectively suppressing the recombination of charges. These findings offer significant guidance for the design and optimization of high-performance photoelectrochemical catalysts.

Substitutional Cu doping at the cation sites in Ba2YNbO6 toward improved visible-light photoactivity—A first-principles HSE06 study

Artificial photosynthesis holds immense promise for sustainable clean energy harvesting, with recent strides in material engineering with the earth abundant elements enabling efficient utilization of the visible solar spectrum for photoelectrochemical catalytic water splitting. Here, we have investigated the impact of substitutional Cu doping at all three cation sites in Ba2YNbO6 (BYN) using density functional theory calculations at the Heyd-Scuseria-Ernzerhof-06 level. One of the key findings is that the defect formation energy follows the hierarchy Nb > Ba > Y. The presence of an oxygen vacancy (OV) enhances the co-solubility of Cu substitution of Nb, particularly when placed outside the CuO6 unit, while it has a contrary effect for Y substitution. Cu replacement reduces the bandgap as Nb > Y ≫ Ba vis-à-vis pure BYN, while extending it into the visible part of the solar spectrum for Nb and Y replacement cases, albeit with OV causing a slight blue shift to them, without reducing the oxidation state of Cu due to strong charge-delocalization. Cu doping at Y and Nb sites retains the direct band transition character of BYN, a feature removed by OV. While all the bare Cu doped systems exhibit formation of a weak electron polaron, the placement of OV tends to annihilate this except for the system comprising first nearest neighbor placement of an OV relative to the Cu substitution at an Nb site. Notably, Cu doping at the Nb site significantly enhances optical activity, particularly ∼2.0–2.5 eV, resulting in promising candidates for photoelectrochemical catalysts.

Synergistic photoelectrocatalytic degradation of tetracycline using a novel Z‐scheme Zn0.5Ni0.5Fe2O4/SiNWs heterostructure: Towards sustainable antibiotic remediation

AbstractPhotoelectrocatalytic technology (PEC) is an emerging green and sustainable technology for treating antibiotic wastewater. However, its effectiveness is limited by the recombination of photogenerated carriers. To address this issue, the Fenton reaction, an advanced oxidation process, can be coupled with PEC technology to enhance the oxidative degradation of antibiotic wastewater. This research involved creating a Zn0.5Ni0.5Fe2O4/silicon nanowires (SiNWs) Z‐type heterojunction through the spin coating technique, which was then utilized in the PEC coupled Fenton reaction to break down antibiotic wastewater. The inherent electric field and the voltage applied hastened the segregation of e− and h+ within the system. These advantages make the Zn0.5Ni0.5Fe2O4/SiNWs heterojunction highly efficient in removing various antibiotics, including tetracycline (TC), ciprofloxacin (CIP), amoxicillin (AMX), and levofloxacin (LVX). In particular, the Zn0.5Ni0.5Fe2O4/SiNWs heterojunction demonstrated an 82.21% degradation efficiency for TC, exhibiting a kinetic constant (k) of 0.02688 min−1, a rate 2.82 times (4.80 times) greater than that of SiNWs. Experimental findings reveal that Zn0.5Ni0.5Fe2O4/SiNWs exhibit superior light absorption properties and a reduced rate of photogenerated charge recombination. The doping of Zn0.5Ni0.5Fe2O4 effectively improves the catalytic performance of SiNWs. This research offers fresh insights into researching PEC‐coupled Fenton reaction methods for the degradation of antibiotics and paves the way for advancing the creation of more potent photoelectrochemical catalysts in the future.

Investigating BiMeVOx compounds as potential photoelectrochemical and electrochemical materials for renewable hydrogen production

In this study, BiMeVOx compounds (where Me: Co, Mo, Ce, Zr) were synthesized and characterized as potential photoelectrochemical materials for solar water splitting, the hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). The analysis confirmed the successful formation of phase BiMeVOx compounds with the desired crystal structure. Among the tested materials, BiCoVOx(800) showed the highest photocurrent density (674 μA cm−2) and HER/OER activity (Tafel slope: HER = 100 mV dec−1 and OER = 75 mV dec−1), followed by BiMoVOx(800), BiCeVOx(800), and BiZrVOx(800). The superior photoelectrochemical performance of BiCoVOx(800) can be attributed to its unique electronic structure and optimized band alignment, which promote efficient charge separation and facilitate the water splitting and hydrogen evolution processes. The findings of this study highlight the promising potential of the synthesized BiMeVOx materials, particularly BiCoVOx, as efficient photoelectrochemical catalysts for water splitting. These results contribute to the advancement of renewable energy technologies and provide valuable insights for the design and development of novel photoactive materials.

Constructing Z-Scheme 3D WO3@Co2SnO4 Heterojunction as Dual-Photocathode for Production of H2O2 and In-Situ Degradation of Organic Pollutants

As photoelectrochemical catalyst material, Z-scheme heterojunction 3D WO3@Co2SnO4 composites were designed through a hydrothermal-calcination method. The morphology and structure were characterized by SEM, EDS, XRD, XPS, DRS, and Mott–Schottky analysis, and the photoelectrochemical properties were explored with the transient photocurrent and electrochemical impedance. The construction of Z-scheme heterojunction markedly heightened the separation efficiency of photogenerated electron-hole pairs of WO3 and enhanced the light absorption intensity, retaining the strong redox ability of the photocatalyst. The 3D WO3@Co2SnO4 was used as a photocathode for production of H2O2. Under the optimal reaction conditions, the yield of H2O2 can reach 1335 μmol·L−1·h−1. The results of free radial capture and rotating disc test revealed the existence of direct one-step two-electron and indirect two-step one-electron oxygen reduction to produce H2O2. Based on the excellent H2O2 production performance of the Z-scheme heterojunction photoelectrocatalytic material, 3D WO3@Co2SnO4 and stainless-steel mesh were used to construct a dual-cathode photoelectric-Fenton system for in-situ degradation of a variety of pollutants in water, such as dye (Methyl orange, Rhodamine B), Tetracycline, sulfamethazine, and ciprofloxacin. The fluorescence spectrophotometry was used to detect hydroxyl radicals with terephthalic acid as a probe. Also, the photocatalytic degradation mechanism was revealed, indicating the dual-cathode photoelectron-Fenton system displayed satisfactory potential on degradation of different types of environmental pollutants. This work provided insights for designing high-activity photoelectrocatalytic materials to produce H2O2 and provided possibility for construction of a photoelectric-Fenton system without extra additions.

Donor-Acceptor Conjugated Acetylenic Polymers for High-Performance Bifunctional Photoelectrodes.

Due to the drastic required thermodynamical requirements, a photoelectrode material that can function as both a photocathode and a photoanode remains elusive. In this work, we demonstrate for the first time that, under simulated solar light and without co-catalysts, donor-acceptor conjugated acetylenic polymers (CAPs) exhibit both impressive oxygen evolution (OER) and hydrogen evolution (HER) photocurrents in alkaline and neutral medium, respectively. In particular, poly(2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine) (pTET) provides a benchmark OER photocurrent density of ~200 μA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) at pH 13 and a remarkable HER photocurrent density of ~190 μA cm-2 at 0.3 V vs. RHE at pH 6.8. By combining theoretical investigations and electrochemical-operando Resonance Raman spectroscopy, we show that the OER proceeds with two different mechanisms, with the electron-depleted triple bonds acting as single-site OER in combination with the C4-C5 atoms of the phenyl rings as dual sites. The HER, instead, occurs via an electron transfer from the tri-acetylenic linkages to the triazine rings, which act as the HER active sites. This work represents a novel application of organic-based materials and contributes to the development of high-performance photoelectrochemical catalysts for the solar fuels' generation.

Single Atom Catalysts for Photoelectrochemical Water Splitting

AbstractSingle atom catalysts (SACs) have attracted increasing attention in electrocatalysis due to their unprecedented catalytic activity with excellent atomic utilization efficiency derived from unique electronic states and coordination environments. In photoelectrochemical (PEC) water splitting, atomically dispersed metal catalysts anchored to photoelectrodes offer the breakthrough to outperform the conventional thin‐film PEC catalysts by enlarging the catalytic sites and facilitating photogenerated charge carrier kinetics. Herein, we present a comprehensive review of SAC‐incorporated photoelectrodes for efficient PEC water splitting. Firstly, the representative characterization techniques for the identification of SACs and investigations in respect of photogenerated charge carrier kinetics and photon‐to‐current efficiency will be discussed. Then, we will introduce the state‐of‐the‐art PEC‐SACs classified into noble metal, non‐noble metal, and dual metal SACs. Finally, critical outlooks to realize the full potential of SACs in photoelectrocatalysis will be highlighted.

A semiconductor-electrocatalyst nano interface constructed for successive photoelectrochemical water oxidation

Photoelectrochemical water splitting has long been considered an ideal approach to producing green hydrogen by utilizing solar energy. However, the limited photocurrents and large overpotentials of the anodes seriously impede large-scale application of this technology. Here, we use an interfacial engineering strategy to construct a nanostructural photoelectrochemical catalyst by incorporating a semiconductor CdS/CdSe-MoS2 and NiFe layered double hydroxide for the oxygen evolution reaction. Impressively, the as-prepared photoelectrode requires an low potential of 1.001 V vs. reversible hydrogen electrode for a photocurrent density of 10 mA cm−2, and this is 228 mV lower than the theoretical water splitting potential (1.229 vs. reversible hydrogen electrode). Additionally, the generated current density (15 mA cm−2) of the photoelectrode at a given overpotential of 0.2 V remains at 95% after long-term testing (100 h). Operando X-ray absorption spectroscopy revealed that the formation of highly oxidized Ni species under illumination provides large photocurrent gains. This finding opens an avenue for designing high-efficiency photoelectrochemical catalysts for successive water splitting.

Improvement of Chemical Stability of Perovskite Nanocrystals as a Photoelectrochemical Catalyst for Hydrogen Evolution Reaction

Recent advances in the synthesis and processing of perovskite materials have led to significant improvements in their stability under harsh conditions, making them increasingly attractive for use as photo and photoelectrochemical catalysts. In particular, core-shell structured perovskite nanocrystals have greatly enhanced chemical stability, enabling their use in aqueous environments; however, their low conductivity remains a challenge. To address this issue, this study developed two-time cross-linkable core-shell perovskite nanocrystals using two types of silanes, resulting in excellent chemical stability and high conductivity. The first cross-linking reaction was spontaneously initiated in the solution state, forming an ultrathin Si-O-Si amorphous matrix on the surface of the perovskite nanocrystals. The second cross-linking reaction was intentionally induced in the film state by exposing it to UV light. The resulting cross-linked perovskite/SiO2 nanocrystal films exhibited a high packing density, and among four different dopants, the Ag-doped film demonstrated the lowest onset potential for HER in a 0.5 M H2SO4 aqueous solution due to effective band modulation. These findings suggest that the two-time cross-linking approach can significantly enhance the performance of perovskite nanocrystals in photoelectrochemical applications.

Design and Characterization of Zeolite/Serpentine Nanocomposite Photocatalyst for Solar Hydrogen Generation

In this work, a low-cost, high-yield hydrothermal treatment was used to produce nanozeolite (Zeo), nanoserpentine (Serp), and Zeo/Serp nanocomposites with weight ratios of 1:1 and 2:1. At 250 °C for six hours, the hydrothermal treatment was conducted. Various methods are used to explore the morphologies, structures, compositions, and optical characteristics of the generated nanostructures. The morphological study revealed structures made of nanofibers, nanorods, and hybrid nanofibril/nanorods. The structural study showed clinoptilolite monoclinic zeolite and antigorite monoclinic serpentine with traces of talcum mineral and carbonates. As a novel photoelectrochemical catalyst, the performance of the Zeo/Serp (2:1) composite was evaluated for solar hydrogen generation from water splitting relative to its constituents. At −1 V, the Zeo/Serp (2:1) composite produced a maximum current density of 8.44 mA/g versus 7.01, 6.74, and 6.6 mA/g for hydrothermally treated Zeo/Serp (1:1), Zeo, and Serp, respectively. The Zeo/Serp (2:1) photocatalysts had a solar-to-hydrogen conversion efficiency (STH) of 6.5% and an estimated hydrogen output rate of 14.43 mmole/h.g. Consequently, the current research paved the way for low-cost photoelectrochemical catalytic material for efficient solar hydrogen production by water splitting.

Copper as a single metal atom based photo-, electro- and photoelectrochemical catalyst decorated on carbon nitride surface for efficient CO 2 reduction: A review

The processes of photocatalytic CO₂ reduction (pCO₂R) and electrochemical CO₂ reduction (ECO₂R) have attracted considerable interest owing to their high potential to address many environmental and energy-related issues. In this aspect, a single Cu atom decorated on a carbon nitride (CN) surface (Cu–CN) has gained increasing popularity because of its unique advantages, such as excellent atom utilization and ultrahigh catalytic activity. CN—particularly graphitic CN (g-C₃N₄)—is a photo- and electrocatalyst and used as an important support material for single Cu atom-based catalysts. These key functions of Cu–CN-based catalysts can improve the catalytic performance and stability in the pCO₂R and ECO₂R during the application process. In this review, we focus on Cu as a single metal atom decorated on CN for efficient photoelectrochemical CO₂ reduction (pECO₂R), where ECO₂R increases the electrocatalytic active area and promotes electron transfer, while pCO₂R enhances the surface redox reaction by efficiently using photogenerated charges and offering integral activity as well as an active interface between Cu and CN. Interactions of single Cu atom-based photo-, electro-, and photoelectrochemical catalysts with g-C₃N₄ are discussed. Moreover, for a deeper understanding of the history of the development of pCO₂R and ECO₂R, the basics of CO₂ reduction, including pCO₂R and ECO₂R over g-C₃N₄, as well as the structural composition, characterization, unique design, and mechanism of a single atom site are reviewed in detail. Finally, some future prospects and key challenges are discussed.

Single-Source Deposition of Mixed-Metal Oxide Films Containing Zirconium and 3d Transition Metals for (Photo)electrocatalytic Water Oxidation.

The fabrication of mixed-metal oxide films holds promise for the development of practical photoelectrochemical catalyst coatings but currently presents challenges in terms of homogeneity, cost, and scalability. We report a straightforward and versatile approach to produce catalytically active zirconium-based films for electrochemical and photoelectrochemical water oxidation. The mixed-metal oxide catalyst films are derived from novel single-source precursor oxide cage compounds containing Zr with first-row transition metals such as Co, Fe, and Cu. The Zr-based film doped with Co on fluorine-doped tin oxide (FTO)-coated glass exhibits the highest electrocatalytic O2 evolution performance in an alkaline medium and an operational stability above 18 h. The deposition of this film onto a BiVO4 photoanode significantly enhances its photoelectrochemical activity toward solar water oxidation, lowering the onset potential by 0.12–0.21 V vs reversible hydrogen electrode (RHE) and improving the maximum photocurrent density by ∼50% to 2.41 mA cm–2 for the CoZr-coated BiVO4 photoanodes compared to that for bare BiVO4.

Elemental diversity-enhanced HER and OER photoelectrochemical catalytic performance in FeCo-AuNP/nitrogen-carbon composite catalysts

High-performance electrochemical or photoelectrochemical catalysts are greatly desired in energy preservation and matter conversion, and so their design and preparation has attracted significant attention. Studies attempting to unveil the general principles for high catalytic performance are especially appealing. Herein, we investigate the mechanism from a componential perspective, with the aim of elucidating the relationship between (photo)electrochemical catalytic performance and elemental diversity. The results indicate that the HER and OER electrochemical and photoelectrochemical catalytic capacities are enhanced with an increase in the diversity of elements. Favorable electronic structures and strengthened internal electric fields are important factors for the observed improvements in performance. This work will provide new insights into the design and synthesis of high-performance electrochemical and photochemical catalysts via reductive deposition, chemical vapor doping, or electrochemical deposition, for the formation of nanostructures possessing multiple elements.

Plasmon Au modified 3D-nanostructrue CoOx decorated hematite for highly efficient photoelectrochemical water splitting

Surface modification and interface engineering are efficient strategies to address the serious charge recombination and the sluggish water oxidation kinetics in photoelectrochemical water splitting. In this work, CoOx decorated hematite nanosheets (Fe2O3/CoOx) are deposited on Nickel foam by the in-situ hydrothermal process. Au nanoparticles are incorporated on Fe2O3/CoOx semiconductors (Fe2O3/CoOx/Au) by electrochemical deposition. In photoelectrochemical test, Fe2O3/CoOx attains a photocurrent density of 1.87 mA cm−2 at 1.23 VRHE, which is 4.45 times that for α-Fe2O3. The onset potential of Fe2O3/CoOx decreases by 266 mV compared with α-Fe2O3. The 3D-nanostructrue Fe2O3/CoOx/Au attains a photocurrent density of 3.88 mA·cm−2 at 1.23 VRHE, which is 9.24 times that of ɑ-Fe2O3. The applied bias photon-to-current efficiency, charge separation and charge injection efficiency of Fe2O3/CoOx/Au are improved. EIS studies show the co-modification of CoOx and Au reduces charge transfer resistance. This strategy would provide a potential approach to promote light absorption and charge separation for photoelectrochemical catalyst.

One-Dimensional Co(OH)F as a Noble Metal-Free Redox Mediator and Hole Extractor for Boosted Photoelectrochemical Water Oxidation in Worm-like Bismuth Vanadate

In this work, a noble metal-free one-dimensional Co(OH)F and hierarchical BiVO₄ combination as a model system is proposed for an efficient photoelectrochemical catalyst. BiVO₄, known for its superior theoretical current density of 7.5 mA/cm², suffers from poor photoelectrochemical performance due to the sluggish water oxidation kinetics, recombination of photogenerated carriers, and results in reduced photoelectrochemical water oxidation. BiVO₄/Co(OH)F photoanode exhibits an enhanced photocurrent and a cathodic shift of 160 mV in onset potential as compared to the pristine BiVO₄ photoanode. Cyclic voltametric studies reveal that cobalt exists in the mixed valence state. The presence of fluorine by virtue of its high electronegativity induces facile positive charge on the metal center, i.e., on cobalt, thereby Co²⁺ ions as an active site accept holes more efficiently from the semiconductor and oxidized to Co³⁺ or/and Co⁴⁺. Subsequently, these active species, Co³⁺ or/and Co⁴⁺, deliver the positive charge to produce O₂ and recover to the initial state to regenerate redox couple. A mechanistic study reveals that Co(OH)F nanorods as an efficient hole extractor by virtue of its redox ability, suppresses the recombination of photogenerated electron–hole at the electrolyte/semiconductor interface and accelerates the water-oxidation kinetics. Co(OH)F modification of the BiVO₄ surface is able to utilize a higher number of holes, which have reached the semiconductor/electrolyte interface for water oxidation that resulted in a photocurrent of 3.4 mA/cm². Investigations on the hole transfer efficiency reveals a faster oxidation kinetics, resulting in improved charge injection in the presence of Co(OH)F. Electrochemical impedance measurements shows a low interfacial charge transfer resistance leading to better photoelectrochemical performance. A Faradaic yield of ∼95% suggests that the generated charge carriers (anodic photocurrent) in the BiVO₄/Co(OH)F photoanode is predominantly due to water oxidation.

Integration of Fe3O4 nanospheres and micropyramidal textured silicon wafer with improved photoelectrochemical performance

Silicon (Si)-based composites have attracted extensive attention for photoelectrochemical (PEC) application. Herein, micropyramidal textured Si wafer was constructed by wet chemical etching method. Hydrothermally synthesized Fe3O4 nanospheres were further deposited on the micropyramids by a simple dip-coating approach. The integrated Fe3O4 nanospheres and Si micropyramids (denoted as Fe3O4@SiMPs) revealed 20 times of higher PEC efficiency than planar Si wafer, without obvious photocurrent decay and crystalline structure change during chronoamperometry test. The greatly enhanced PEC performance of Fe3O4@SiMPs is largely attributed to the seamless integration of Si micropyramids and Fe3O4 nanospheres. The micropyramidal textured structure can enhance light absorption by reducing the surface reflectance and enhancing the light trapping effect. The micropyramids and Fe3O4 nanospheres on the surface of planar Si wafer offer more specific surface area for the contact of electrode with electrolyte. The Fe3O4 nanospheres not only protect the micropyramids from corrosion, but also accelerate the PEC kinetics by promoting charge transfer between the electrode and the electrolyte. This study can inspire the optimal design of Si wafer-based nanocomposites as efficient PEC catalysts for overall water splitting.

When multiferroics become photoelectrochemical catalysts: A case study with BiFeO3/La2NiMnO6

The multiferroic perovskite oxide BiFeO3 (BFO), other than the conventional semiconductor oxides, is a promising absorber for water photolysis in photoelectrochemical cells (PECs). However, BFO has very limited ability to split the water because of its inefficient light absorption in the visible region, large carrier recombination rate, reduced surface area and poor charge transport. A way to overcome these limitations is the incorporation of a narrow direct band gap semiconductor such as La2NiMnO6 (LNMO), and to create a plum pudding type composite with BFO. The BFO/LNMO composite with a band gap of 1.34–1.48 eV (depending on the molar fraction of LNMO) has an enhanced photocurrent (~14.07 mA/cm2) and an applied bias photon-to-current conversion efficiency (~9.61%). The improved PEC performance is attributed to its improved light absorbance in the visible region, better carrier transport, increased surface area and higher dielectric constant. In respect of narrow direct band gap, BFO/LNMO composite is also quite promising for photovoltaic application.

Catalytic Mismatching of CuInSe2 and Ni3Al Demonstrates Selective Photoelectrochemical CO2 Reduction to Methanol

Photoelectrochemical catalysts are often plagued by ineffective interfacial charge transfer or nonideal optical conversion properties. To overcome this challenge, strategically pairing a catalytica...

Development and characterization of rGO supported CdS[sbnd]MoS2 photoelectrochemical catalyst for splitting water by visible light

Development of a mixed phase MoS2 (1T/2H)CdS supported on rGO photo-electrochemical catalyst for hydrogen production by splitting of water using visible light, has been reported. This catalyst showed a better efficiency compared to catalysts where either MoS2 was incorporated with CdS or MoS2 alone was supported on rGO. All the catalysts were photoactive under negative biasing. A detailed characterization of catalysts was performed using FTIR, XRD, DRS, HRSEM, HRTEM, SAED, XPS, and EIS etc. Higher activity of MoS2CdS-rGO correlated with the formation of a mixed phase of MoS2, as well as a heterojunction at the interfaces of MoS2CdS-rGO. Formation of the heterojunction and the presence of mixed phases of MoS2 have resulted into a better charge separation, a higher charge density and low resistance for charge transfer. These factors have attributed a higher efficiency of the catalyst. The probable mechanism of charge transfer is also discussed.

Manipulation of Charge Transport by Metallic V13 O16 Decorated on Bismuth Vanadate Photoelectrochemical Catalyst.

Conductive metal oxides represent a new category of functional material with vital importance for many modern applications. The present work introduces a new conductive metal oxide V13 O16 , which is synthesized via a simplified photoelectrochemical procedure and decorated onto the semiconducting photocatalyst BiVO4 in controlled mass percentages ranging from 25% to 37%. Owing to its excellent conductivity and good compatibility with oxide materials, the metallic V13 O16 -decorated BiVO4 hybrid catalyst shows a high photocurrent density of 2.2 ± 0.2 mA cm-2 at 1.23 V versus reversible hydrogen electrode (RHE). Both experimental characterization and density functional theory calculations indicate that the superior photocurrent derives from enhanced charge separation and transfer, resulting from ohmic contact at the interface of mixed phases and superior electrical conductivity from V13 O16 . A Co-Pi coating on BiVO4 -V13 O16 further increases the photocurrent to 5.0 ± 0.5 mA cm-2 at 1.23 V versus RHE, which is among the highest reported for BiVO4 -based photoelectrodes. Surface photovoltage and transient photocurrent measurements suggest a charge-transfer model in which photocurrents are enhanced by improved surface passivation, although the barrier at the Co-Pi/electrolyte interface limits the charge transfer.