Charge Recombination Kinetics Research Articles

Plasma-enhanced Ni atom-modulated Co-OH to promote surface charge transfer of CuWO4 photoanode for efficient solar hydrogen evolution

The high charge recombination and slow transfer kinetics of photoanode remains to be great challenges in photo-electrochemistry (PEC). While, the semiconductor (CuWO4)/layered double-metal hydroxides (LDHs)/plasma coupling strategy is identified as one of the effective methods to enhance the PEC behaviors. The LDHs act as hole-conducting layers to promote interfacial catalytic reactions of PEC and release charges from the CuWO4 photoanode, which effectively enhances charge separation and boosts kinetic processes. Metallic Ag nanoparticles enhances light-absorbing capacity of the photoanode, as well as improves charge separation and kinetics of the photoanode utilizing the surface plasmon resonance (SPR) effect for increasing carrier groups and facilitatingcharge separation. The study shows that the CuWO4/NiCo-LDH/Ag photoanode prepared via as-mentioned coupling strategy exhibits a potential photocurrent density of 2.84 mA·cm−2 at 1.23 V vs. RHE, which is 9.2 times higher than that of the pristine CuWO4 (0.31 mA·cm-2) in phosphate buffered electrolyte. Moreover, it is determined that a special charge-trapping states (surface state) exists during the charge transfer process, which plays an indispensable role for the charge storage and transfer. Density Functional Theory (DFT) calculations validate that the introduction of NiCo-LDH and Ag facilitates charge transfer, whereas the modulation of the rate-determining steps (RDS) boosts the overall efficiency of the reaction. This study presents a guiding design approach for regulating PEC behavior of the semiconductor/LDHs/plasma strategy.

Microwave Synthesis of (g‐C3N4)−BiVO4: Selective Adsorption and Photocatalytic Activity Towards Dye Degradation

AbstractPhotocatalytic degradation of pollutants has been extensively studied. Among the investigated photocatalysts, BiVO4 has emerged as a very promising material. BiVO4 is known for its narrow band‐gap energy suitable for solar‐driven reactions; however, it is subjected to challenges such as charge recombination and slow electron transfer kinetics. Combining BiVO4 with g‐C3N4 proves promising, aligning energy levels and leveraging unique charge transport properties to enhance dye degradation under visible light. This study reports a novel synthesis of g‐C3N4−BiVO4 heterojunction through in‐situ urea pyrolysis, ensuring homogeneous dispersion. While maintaining the monoclinic structure of BiVO4, the heterojunction exhibits increased surface area and a more negative zeta potential, influencing catalyst‐substrate to be degraded interactions. Adsorption studies reveal distinct behaviors with cationic dyes (MB and RhB) forming multilayers, hindering light absorption, and reducing photocatalytic efficiency. Conversely, the heterojunction performs efficiently with the anionic MO dye. Photoelectrochemical studies show that the heterojunction has succeeded in promoting the separation of photogenerated charges. The study lays the groundwork for optimizing synthesis methods and designing nanocomposites with superior photocatalytic activities.

Boosting photoelectrochemical water oxidation by self-assembled Co@β-cyclodextrin supramolecules modified on BiVO4 photoanode

Severe charge recombination and poor surface water oxidation kinetics are key restrictions of BiVO4 photoanode for efficient photoelectrochemical (PEC) water oxidation. In order to overcome this issue, we introduce Co@β-cyclodextrin (Co@β-CD) supramolecule as oxidation evolution catalyst (OEC) into BiVO4 photoanode for the first time via a facile two-step immersion method. The optimal Co@β-CD/BiVO4 photoanode displays a remarkable photocurrent density of 5.3 mA cm−2 at 1.23 VRHE, which is ca. 3.5 times as high as that of pristine BiVO4 photoanode. Further analyses indicate that photogenerated holes could quickly transfer from BiVO4 to Co sites through β-CD, thereby suppressing charge recombination. Moreover, due to the spatial confinement effect of β-CD, the dispersed Co sites in Co@β-CD are considered to possess the high catalytic activity in similar with single-atom catalyst, which accelerates the surface water oxidation kinetics. This work not only demonstrates the superiority of supramolecule/semiconductor composite photoanode, but also provides a facile preparation route for the large-scale preparation of high-performance photoanodes.

Monte Carlo random walk simulation of transient absorption kinetics using reflectance and absorption of electrons at Au/TiO2 nanoparticle boundaries

To understand plasmon-induced charge-transfer mechanisms between a photo-excited gold (Au) nanoparticle and a TiO2 nanoparticle, a Monte Carlo random walk (MCRW) simulation was applied to reproduce the charge recombination kinetics in the nanocrystalline (Au/TiO[Formula: see text] assemblies reported previously based on transient absorption spectroscopy. The Au/TiO2 assemblies consist of a confined electron diffusion space within a tiny TiO2 nanoparticle, making it possible to study electron diffusion transport through MCRW simulation. In this simulation algorithm, the electron diffusion starts at the coordinate origin of a rectangle, and the next direction of movement is obtained by calculating the coordinate matrix and random offset so that the electron is reflected on three boundaries and absorbed when it reaches the other boundary. By simulation programming, the histogram which indicates the occurrence frequency of the step accumulation number up to the right boundary was obtained. From 100 to 100000 steps under condition of 10000 iteration, that is, changing the steps but keeping the iteration times to ensure that all particles experience absorption in the simulation. Comparing the trace of 106 particles position with that of 104 under 1000 simulations, the electron density was found to saturate other than the region near the right boundary, where electrons disappear by the absorption process during the electron diffusion process. Finally, by fitting curves, it is confirmed that the tendency of the simulated response reproduced the transient absorption kinetics.

Exploring the role of Ti3C2TxMXene in photoelectrochemical water splitting over solution-processed BiVO4 photoanode

Transition metal carbides, nitrides, or carbonitrides known as MXenes commonly improve the efficiency of photo(electro)catalysts, but their role is still not fully explored. Herein, we developed a novel and facile solution-processing method to fabricate BiVO4 and Ti3C2Tx-modified BiVO4 (Ti3C2Tx/BiVO4) photoanodes to explore the role of Ti3C2Tx MXene in photoelectrochemical water splitting. The charge transfer and recombination kinetics were studied by transient open-circuit potential, transient photocurrent, photoelectrochemical impedance spectroscopy, and intensity-modulated photocurrent spectroscopy. It was demonstrated that Ti3C2Tx forms a Schottky-like junction at the BiVO4/Ti3C2Tx interface and that it acts as a hole transport/storage layer. The Ti3C2Tx layer creates a built-in electric field at the surface that increases the band bending and space charge layer width, eventually enhancing the charge separation efficiency. Modification of Ti3C2Tx/BiVO4 with a water oxidation catalyst such as cobalt phosphate (Co-Pi) was essential to deliver the maximum photocurrent. For instance, the Co-Pi/Ti3C2Tx/BiVO4 photoanode delivered 4.72 mA/cm−2 at 1.23 VRHE, which is 2- and 11-fold higher than those of Ti3C2Tx/BiVO4 and pristine BiVO4 photoanodes, respectively. This study provides a practical protocol for fabricating Ti3C2Tx/BiVO4 and reveals the role of MXene in photoelectrochemical water splitting.

Construction of type-II SnO2/InGaN nanorods heterostructure toward high photoelectrochemical performance

Exploring highly efficient and stable photoelectrode material is essential for high-performance photoelectrochemical (PEC) water-splitting applications. III-nitride semiconductors, particularly InGaN, have been considered as prospective materials for PEC hydrogen evolution. However, their surface states and other recombination centers, which enhance the charge recombination kinetics, are bottlenecks for the high PEC performance. In this work, we report the construction of type-II heterojunction by sputter depositing SnO2 on InGaN nanorods (NRs) to promote interfacial carrier transport and thereby enhance PEC performance. The energy band offsets at the SnO2/InGaN NRs interface were analyzed by x-ray photoelectron spectroscopy. Type-II heterojunction was defined at the SnO2/InGaN NRs interface with a valence band offset of 0.77 eV and conduction band offset of 0.25 eV. The photocurrent density of the SnO2/InGaN NRs photoanode is 7.09 mA/cm2 at 0.77 V vs Ag/AgCl electrode with 80 nm SnO2 thickness, which is ∼14-fold higher than that of the pristine InGaN NRs photoanode. Furthermore, the applied bias photo-to-current efficiency of SnO2/InGaN NRs photoanode records 3.36% at 0.77 V vs Ag/AgCl electrode. The enhanced PEC performance is mainly ascribed to the formation of high-quality SnO2/InGaN NRs heterojunction that enforces the directional charge transfer and substantially boosts the separation of photogenerated electron–hole pairs at the interface of InGaN NRs and SnO2. Overall, this work sheds light on the promising strategy to design and fabricate III-nitride nanostructures-based photoelectrodes for feasible PEC water-splitting applications.

MoO3/BiVO4 heterojunction modified with cobalt-manganese layered double hydroxide cocatalyst for photoelectrochemical water oxidation

To improve the charge recombination and poor oxygen evolution reaction (OER) kinetics of BiVO4, in this paper, a high-performance CoMn-LDH/MoO3/BiVO4 photoanode was synthesized by a simple electrodeposition and calcination method. CoMn-LDH/MoO3/BiVO4 shows a photocurrent density of 3.78 mA cm−2 at 1.23 V vs. RHE, which is 3.78 times higher than that of pure BiVO4 with negative shift onset potentials of 330 mV. The maximum applied bias photon-to-current efficiency (ABPE) and incident photon-to-current conversion efficiency (IPCE) are 1.24 % and 55.5 %, respectively, which are 13.8 and 12.5 times higher than those of pure BiVO4. In-depth studies demonstrate that the MoO3/BiVO4 heterojunction can better drive the transfer of photogenerated carriers and suppress bulk charge recombination, CoMn-LDH improves the OER kinetics and broadens the absorption of visible light, their synergistic effect significantly enhances charge separation and light harvesting of BiVO4. This work provides a facile electrodeposition method to fabricate highly efficient photoanodes for solar-driven water splitting.

Extremely low onset potential of modified Fe2O3 photoanode for water oxidation

The photoelectrochemical (PEC) performance of hematite (α-Fe2O3)-based photoanodes is still far from its theoretical value because they are constrained by serious charge recombination and sluggish water oxidation kinetics. Herein, we developed a heterostructural photoanode by coating boron doped graphite carbon nitride nanolayers onto an Fe2O3 nanoarray (BCN/Fe2O3), followed by modification with NiCo(OH)x cocatalyst. The constructed NiCo(OH)x/BCN/Fe2O3 demonstrates a significantly improved photocurrent density of 2.7 mA cm−2 at 1.23 VRHE (V versus reversible hydrogen electrode), which is 3.2 times higher than that of pristine Fe2O3. Additionally, it exhibits an extremely negative onset potential of 0.60 VRHE. Detailed studies reveal that the BCN/Fe2O3 heterojunction endows a driving force for charge separation and establishes a direct pathway for their transport, while NiCo(OH)x acts as a cocatalyst to accelerate the surface water oxidation reaction.

Revealing Charge-Transfer Dynamics at Buried Charge-Selective Heterointerface in Highly Effective Perovskite Solar Cells.

The suboptimal carrier dynamics at the heterointerface between the perovskite and charge transport layer severely limit further performance enhancement of the state-of-the-art perovskite solar cells (PSCs). Herein, we completely map charge carrier extraction and recombination kinetics over a broad time range at buried electron-selective heterointerfaces via ultrafast transient technologies. It is revealed that the heterointerfaces carefully contain the electronic processes of free charge generation in perovskite within ∼2.8 ps, relaxation process of trap-state induced electron capturing less than ∼10.0 ps, electron extraction from perovskite to SnO2 within ∼194 ps, trap-assisted recombination within ∼2047 ps, and recombination between back-injected electrons and remaining holes within ∼8.4 ns. Moreover, we further demonstrate that the inserted poly(vinyl alcohol) (PVA) thin layer can effectively enhance the electron extraction from perovskite to SnO2, block the undesired electron back injection, and significantly suppress the nonradiative recombination, contributing to the improved device parameters of photovoltage and fill factor. This work sheds light on charge-transfer limitations at the perovskite buried heterointerface and provides an effective guide of ideal heterointerface design for promoting charge transfer and improving PSC performance.

Changing Directions: Influence of Ligand Electronics on the Directionality and Kinetics of Photoinduced Charge Transfer in Cu(I)Diimine Complexes.

A key challenge to the effective utilization of solar energy is to promote efficient photoinduced charge transfer, specifically avoiding unproductive, circuitous electron-transfer pathways and optimizing the kinetics of charge separation and recombination. We hypothesize that one way to address this challenge is to develop a fundamental understanding of how to initiate and control directional photoinduced charge transfer, particularly for earth-abundant first-row transition-metal coordination complexes, which typically suffer from relatively short excited-state lifetimes. Here, we report a series of functionalized heteroleptic copper(I)bis(phenanthroline) complexes, which have allowed us to investigate the directionality of intramolecular photoinduced metal-to-ligand charge transfer (MLCT) as a function of the substituent Hammett parameter. Ultrafast transient absorption suggests a complicated interplay of MLCT localization and solvent interaction with the Cu(II) center of the MLCT state. This work provides a set of design principles for directional charge transfer in earth-abundant complexes and can be used to efficiently design pathways for connecting the molecular modules to catalysts or electrodes and integration into systems for light-driven catalysis.

Highly Effective B@g‐C3N4/Polyaniline Nanoblend for Photoelectrocatalytic Reduction of CO2 to Methanol

AbstractPhotoelectrocatalytic (PEC) conversion of CO2 has been extensively investigated as it uses solar energy to combine CO2 and water to produce hydrocarbons. In the present work, B@graphitic carbon nitride (g‐C3N4)/polyaniline (PANI) nanoblend was synthesized by in situ polymerization of aniline in the presence of B@g‐C3N4 for PEC CO2 reduction. The catalyst was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy, X‐ray diffraction, UV‐Vis absorption spectroscopy, photoluminescence, X‐ray photoelectron spectroscopy (XPS), and Mott‐Schottky analysis. The PEC activity was evaluated by linear sweep voltammetry (LSV) and chronoamperometry. XRD revealed the formation of g‐C3N4, while B doping was confirmed by XPS. The presence of PANI was visualized by FESEM. A remarkable cathodic current associated with CO2 reduction was observed during LSV from an onset potential of –0.01 V vs. normal hydrogen electrode (NHE), which is more positive than that of B@g‐C3N4 (–0.82 V vs. NHE), and the positive shift is attributed to the slow charge recombination kinetics of B@g‐C3N4/PANI as evidenced by PL results. The mechanism of PEC CO2 reduction was investigated and discussed on the basis of the Mott‐Schottky results. In conclusion, B@g‐C3N4/PANI opens a new avenue to develop photoelectrocatalysts for PEC CO2 reduction to methanol.

Better Covalent Connection in a Molecular Triad Enables More Efficient Photochemical Energy Storage.

Numerous studies have explored the kinetics of light-induced charge separation and thermal charge recombination in donor-acceptor compounds, but quantum efficiencies have rarely been investigated. Here, we report on two essentially isomeric molecular triads, both comprising a π-extended tetrathiafulvalene (ExTTF) donor, a ruthenium(II)-based photosensitizer, and a naphthalene diimide (NDI) acceptor. The key difference between the two triads is how the NDI acceptor is connected. Linkage at the NDI core provides stronger electronic coupling to the other molecular components than connection via the nitrogen atoms of NDI. This change in molecular connectivity is expected to accelerate both energy-storing charge separation and energy-wasting charge recombination processes, but it is not a priori clear how this will affect the triad's ability to store photochemical energy; any gain resulting from faster charge separation could potentially be (over)compensated by losses through accelerated charge recombination. The new key insight emerging from our study is that the quantum yield for the formation of a long-lived charge-separated state increases by a factor of 5 when going from nitrogen- to core-connected NDI, providing the important proof of concept that better molecular connectivity indeed enables more efficient photochemical energy storage. The physical origin of this behavior seems to root in different orbital connectivity pathways for charge separation and charge recombination, as well as in differences in the relevant orbital interactions depending on NDI connection. Our work provides guidelines for how to discriminate between energy-storing and energy-wasting electron transfer reactions in order to improve the quantum yields for photochemical energy storage and solar energy conversion.

The Emergence of 2D Building Units in Metal‐Organic Frameworks for Photocatalytic Hydrogen Evolution: A Case Study with COK‐47

AbstractMetal‐organic frameworks (MOFs) are promising materials for photocatalytic water splitting reactions, but examples of visible light‐responsive, catalytically active, and stable MOFs are still rare. A detailed investigation is conducted for COK‐47 – a recently described MOF comprising 2D Ti‐O6 secondary building units (SBUs) – toward a photocatalytic hydrogen evolution reaction (HER), showing how overall particle morphology, surface area, and missing ligand defects are central parameters governing the material's ultimate performance. The newly synthesized COK‐47ISO is among the most active MOFs to date, yielding HER‐rates of 8.6 µmol h−1, and an apparent quantum yield (AQY) of 0.5% under visible light illumination. Optoelectronic and photoluminescence investigations, supported by theoretical calculations, enable the unraveling of its electronic structure along with charge transfer and recombination kinetics. A wavelength‐dependent reaction mechanism is proposed involving ligand to metal charge transfer (LMCT) and the main challenges for visible or UV photoexcitation are identified, demonstrating that the unique 2D layered structure aids charge separation and is key to the high performance. This work introduces COK‐47 as a promising alternative to the well‐known MIL‐125 family and offers directions for future studies

Stochastic theory of charge dynamics and recombination in defect clusters in bulk silicon

Various types of defect clusters are generated in bulk Si-based high-energy particle detectors. They become either recombination centres or charge trapping centres. Populated trapping centres create internal fields which may affect the dynamics and recombination of remaining free charges. In the semiclassical regime, the charge dynamics can be described by the Boltzmann equation. In this paper, the stochastic description is presented as an alternative to a direct solution of the Boltzmann equation approach. It is demonstrated that the hole dynamics can be described in the overdamped regime in both light-hole and heavy-hole cases. Electrons have to be described by including ballistic components. The theory allows an efficient simulation of the electron and hole dynamics in the vicinity of a defect cluster and demonstrates that local trapping centres are the major components enabling fast charge recombinations. The dipolar type internal fields of permanently trapped charges only weakly influence the charge recombination kinetics.

Dual modification of BiVO4 photoanode for synergistically boosting photoelectrochemical water splitting

Bismuth vanadate (BiVO4) is a promising nanomaterial for photoelectrochemical (PEC) water oxidation. However, the serious charge recombination and sluggish water oxidation kinetics limit its performance. Herein, an integrated photoanode was successfully constructed by modifying BiVO4 (BV) with In2O3 (In) layer and further decorating amorphous FeNi hydroxides (FeNi). The BV/In/FeNi photoanode exhibited a remarkable photocurrent density of 4.0 mA cm−2 at 1.23 VRHE, which is approximately 3.6 times larger than that of pure BV. And the water oxidation reaction kinetics has an over 200% increased. This improvement was mainly because the formation of BV/In heterojunction inhibited charge recombination, and the decoration of cocatalyst FeNi facilitated the water oxidation reaction kinetics and accelerated hole transfer to electrolyte. Our work provides another possible route to develop high-efficiency photoanodes for practical applications in solar conversion.

Electro- and Photoinduced Interfacial Charge Transfers in Nanocrystalline Mesoporous TiO2 and TiO2/Iron Porphyrin Sensitized Films under CO2 Reduction Catalysis.

Electro- and photochemical CO2 reduction (CO2R) is the quintessence of modern-day sustainable research. We report our studies on the electro- and photoinduced interfacial charge transfer occurring in a nanocrystalline mesoporous TiO2 film and two TiO2/iron porphyrin hybrid films (meso-aryl- and β-pyrrole-substituted porphyrins, respectively) under CO2R conditions. We used transient absorption spectroscopy (TAS) to demonstrate that, under 355 nm laser excitation and an applied voltage bias (0 to -0.8 V vs Ag/AgCl), the TiO2 film exhibited a diminution in the transient absorption (at -0.5 V by 35%), as well as a reduction of the lifetime of the photogenerated electrons (at -0.5 V by 50%) when the experiments were conducted under a CO2 atmosphere changing from inert N2. The TiO2/iron porphyrin films showed faster charge recombination kinetics, featuring 100-fold faster transient signal decays than that of the TiO2 film. The electro-, photo-, and photoelectrochemical CO2R performance of the TiO2 and TiO2/iron porphyrin films are evaluated within the bias range of -0.5 to -1.8 V vs Ag/AgCl. The bare TiO2 film produced CO and CH4 as well as H2, depending on the applied voltage bias. In contrast, the TiO2/iron porphyrin films showed the exclusive formation of CO (100% selectivity) under identical conditions. During the CO2R, a gain in the overpotential values is obtained under light irradiation conditions. This finding was indicative of a direct transfer of the photogenerated electrons from the film to absorbed CO2 molecules and an observed decrease in the decay of the TAS signals. In the TiO2/iron porphyrin films, we identified the interfacial charge recombination processes between the oxidized iron porphyrin and the electrons of the TiO2 conduction band. These competitive processes are considered to be responsible for the diminution of direct charge transfer between the film and the adsorbed CO2 molecules, explaining the moderate performances of the hybrid films for the CO2R.

A Symmetry-Broken Charge-Separated State in the Marcus Inverted Region.

We report a long-lived charge-separated state in a chromophoric pair (DC-PDI2 ) that uniquely integrates the advantages of fundamental processes of photosynthetic reaction centers: i) Symmetry-breaking charge-separation (SB-CS) and ii) Marcus-inverted-region dependence. The near-orthogonal bichromophoric DC-PDI2 manifests an ultrafast evolution of the SB-CS state with a time constant of =0.35±0.02 ps and a slow charge recombination (CR) kinetics with =4.09±0.01 ns in ACN. The rate constant of CR of DC-PDI2 is 11 686 times slower than SB-CS in ACN, as the CR of the PDI radical ion-pair occurs in the deep inverted region of the Marcus parabola ( >λ). In contrast, an analogous benzyloxy (BnO)-substituted DC-BPDI2 showcases a ≈10-fold accelerated CR kinetics with lowering to ≈1536 in ACN, by virtue of a decreased CR driving force. The present investigation demonstrates a control of molecular engineering to tune the energetics and kinetics of the SB-CS material, which is essential for next-generation optoelectronic devices.

A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

AbstractWe report a long‐lived charge‐separated state in a chromophoric pair (DC‐PDI2) that uniquely integrates the advantages of fundamental processes of photosynthetic reaction centers: i) Symmetry‐breaking charge‐separation (SB‐CS) and ii) Marcus‐inverted‐region dependence. The near‐orthogonal bichromophoric DC‐PDI2 manifests an ultrafast evolution of the SB‐CS state with a time constant of =0.35±0.02 ps and a slow charge recombination (CR) kinetics with =4.09±0.01 ns in ACN. The rate constant of CR of DC‐PDI2 is 11 686 times slower than SB‐CS in ACN, as the CR of the PDI radical ion‐pair occurs in the deep inverted region of the Marcus parabola ( >λ). In contrast, an analogous benzyloxy (BnO)‐substituted DC‐BPDI2 showcases a ≈10‐fold accelerated CR kinetics with lowering to ≈1536 in ACN, by virtue of a decreased CR driving force. The present investigation demonstrates a control of molecular engineering to tune the energetics and kinetics of the SB‐CS material, which is essential for next‐generation optoelectronic devices.

Surface passivation decoration of amorphous cobalt silicate on molybdenum-doped bismuth vanadate for efficient photoelectrochemical water oxidation

Such a subtly strategy greatly promoted the surface holes consumption rate and made composite photoanode dramatically achieve in 2.82 mA /cm2 at 1.23 VRHE (4.7 - fold higher than BiVO4) with a negative onset potential offset of 207 mV. The amorphous Co - species decoration tremendously enhanced surface charge injection efficiency to almost 90 % at 1.23 VRHE. And the biggest photovoltage and lowest charge recombination kinetics of composite photoanode also presented that the amorphous Co species had the potential ability to be passivation layer which were characterized by OCP and IMPS test.

Surface selective passivation and FexNi1-xOOH co-modified Fe2O3 photoanode toward high-performance water oxidation

Improving the water-splitting performance of hematite (α-Fe2O3) is still hindered due to its severe charge recombination and poor water oxidation kinetics. Herein, borate-treated Ti–Fe2O3 combined with a FexNi1-xOOH cocatalyst (FexNi1-xOOH/B/Ti–Fe2O3) greatly improved the performance of Ti–Fe2O3, and reached a notable photocurrent density of 3.39 mA/cm2 at 1.23 V vs. RHE. Transient surface photovoltage spectroscopy (TPV) directly reveals that [B(OH)4]− as a Lewis base can selectively passivate acceptor surface states on Ti–Fe2O3 photoanode surface, efficiently enhancing the charge separation efficiency. Moreover, the FexNi1-xOOH thin layer is devoted to further facilitate holes injection into the electrolyte, accelerating the water oxidation kinetics of Ti–Fe2O3 photoanode. The synergetic integration of acceptor surface states passivation and FexNi1-xOOH cocatalyst provides a novel strategy for the construction of efficient photoanodes by surface engineering.