Oxygen Evolution Co-catalyst Research Articles

(Invited) Two-Dimensional Metal–Organic Framework Acts As a Hydrogen Evolution Cocatalyst for Overall Photocatalytic Water Splitting

Water-splitting semiconductor photocatalysts require hydrogen evolution reaction (HER) cocatalysts, the majority of which are robust metals and metal oxides. Metal complexes feature designability and reaction selectivity. This feature should be appreciated in the application as HER cocatalysts by suppressing unfavorable back reactions; however, low stability hampers their application. In this research, we demonstrate that a fully π-conjugated and conductive two-dimensional metal–organic framework (2D MOF), which possesses both virtues of metals/metal oxides and metal complexes, serves as an ideal HER cocatalyst candidate. NiBHT, a kind of 2D MOF, is deposited on the photocatalyst SrTiO3:Al with CoO x as an oxygen evolution cocatalyst to show long-term overall one-step water splitting with an apparent quantum efficiency (AQE) of 6.5% at 350 nm. In comparison to Pt as a representative HER cocatalyst, NiBHT turns out to be a suppressor of back reactions related to oxygen reduction reactions, which is proven both experimentally and theoretically.

Rational tailoring of spin-polarized photoelectrode for magnetic-assisted overall water splitting

Photoelectrochemical (PEC) devices could play a significant role in efficient solar-to-fuel production for a sustainable economy. Herein, we report a significant enhancement of PEC water splitting via rational tailoring of ferromagnetic ordered oxygen evolution cocatalysts (OECs) iron-cobalt oxide on the Mo-doped BiVO4 (Mo:BiVO4) surface. The Fe3+ and Co2+ tend to form an optimal electron-filled arrangement, contributing to lower barriers for the oxygen evolution reaction (OER). Benefiting from the Fe/Co dual-site as the catalytic center, the prepared FeCoOx/Mo:BiVO4 photoanode achieves 4.55 mA·cm−2 at 1.23 V vs reversible hydrogen electrode (RHE) with a lower starting potential for OER, outperforming the FeOx/Mo:BiVO4 (2.71 mA·cm−2) and CoOx/Mo:BiVO4 (3.48 mA·cm−2). Importantly, ferromagnetic iron-cobalt oxide as the spin polarizer can optimize the OER kinetics. Under spin-related effects, a magnetic stimulation strategy can further enhance the spin alignment. The corresponding photocurrent of FeCoOx/Mo:BiVO4 is increased up to 5.15 mA·cm−2 under a magnetic field, with ηSep and ηTrans reaching 89 % and 91 %, respectively. Specifically, the spin-polarization process will be helpful for the production of O(↓)O(↓)H intermediates, preferring to produce O2. Hence, this study provides a new pathway for designing highly efficient PEC water splitting systems on magnetic-assisted photoelectrodes.

CoMoP hole transfer layer functionally enhances efficiency and stability of BiVO4 based photoanode for solar water splitting

Engineering the hole transfer layer is a promising approach to suppress the bulk charge recombination of photoanodes for enhancing solar water splitting performance. Herein, functional cobalt-molybdenum bimetallic phosphide (CoMoP) layer are inserted between bismuth vanadate (BiVO4) and NiFeOx oxygen evolution cocatalyst (OEC) as hole transfer layer to construct an integrated photoanode (NiFeOx/CoMoP/BiVO4). This state-of-the-art NiFeOx/CoMoP/BiVO4 photoanode not only achieves a superior photocurrent density of 5.82 mA/cm2 at 1.23 V vs a reversible hydrogen electrode (vs RHE), but also an outstanding 60 h long-term photostability (100 mW/cm2). Such excellent PEC performance can be attributed to the engineering CoMoP hole layer in NiFeOx/BiVO4, promoting hole transfer, retarding bulk charge recombination and accelerating the surface water oxidation kinetics. This study contributes to the role of the hole transfer layer and sheds light on the development of effective and stable photoanodes for PEC water splitting.

Modulating built-in electric field via Bi-VO4-Fe interfacial bridges to enhance charge separation for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting on semiconductor electrodes is considered to be one of the important ways to produce clean and sustainable hydrogen fuel, which is a great help in solving energy and environmental problems. Bismuth vanadate (BiVO4) as a promising photoanode for photoelectrochemical water splitting still suffers from poor charge separation efficiency and photo-induced self-corrosion. Herein, we develop heterojunction-rich photoanodes composed of BiVO4 and iron vanadate (FeVO4), coated with nickel iron oxide (NiFeOx/FeVO4/BiVO4). The formation of the interface between BiVO4 and FeVO4 (Bi-VO4-Fe bridges) enhances the interfacial interaction, resulting in improved performance. Meanwhile, high-conductivity FeVO4 and NiFeOx oxygen evolution co-catalysts effectively enhance bulk electron/hole separation, interface water’s kinetics and photostability. Concurrently, the optimized NiFeOx/FeVO4/BiVO4 possesses a remarkable photocurrent density of 5.59 mA/cm2 at 1.23 V versus reversible hydrogen electrode (vs RHE) under AM 1.5G (Air Mass 1.5 Global) simulated sunlight, accompanied by superior stability without any decreased of its photocurrent density after 14 h. This work not only reveals the crucial role of built-in electric field in BiVO4-based photoanode during PEC water splitting, but also provides a new guide to the design of efficient photoanode for PEC.

Enhanced photoelectrochemical water splitting coupled with pharmaceutical pollutants degradation on Zr:BiVO4 photoanodes by synergetic catalytic activity of NiFeOOH nanostructures

Globally, the emergence of drug-resistant bacteria has created an urgent need for an effective method to remove antibiotics from pharmaceutical wastewater. Engineering Bismuth vanadate (BiVO4) with an oxygen evolution cocatalyst (OEC) holds a promising potential for enhancing water splitting efficiency in the production of hydrogen (H2) using free solar energy. Here, we successfully developed a Zr:BiVO4/NiFeOOH heterojunction by electrodeposition and photoelectrochemical transformation. Zr:BiVO4/NiFeOOH photoanodes exhibit 5 fold superior photocurrent response at 1.23 V compared with Zr:BiVO4 electrodes, since NiFeOOH acts as an oxygen-releasing catalyst. Furthermore, the attained heterojunctioned electrode can effectively degrade TCH, riboflavin, and streptomycin in PEC. The degradation rate of TCH acquired 96% within 1 h, which is 3 times superior than the efficiency reported for pristine Zr:BiVO4 photoelectrodes. By introducing NiFeOOH into BiVO4, electron life-time was increased and electron-hole recombination was suppressed. In this study, we present a solar-driven, sustainable and effective way of treating wastewater and provide new insights into the process.

Double oxygen evolution co-catalysts modified BiVO4 to boost photoelectrochemical water oxidation performance

Improving the kinetics of oxygen evolution is crucial for enhancing the performance of photoelectrochemical (PEC) water splitting. Herein, this study utilizes a chemical self-growth method to grow NiFe tannic acid complex (NFTA) and Co(OH)2 on the surface of BiVO4 photoanode (BiVO4/NFTA/Co). As a result, the synergistic effects of NFTA and Co(OH)2 layers promote the efficiency and stability of BiVO4 photoanode towards PEC water oxidation. The photocurrent density of the obtained BiVO4/NFTA/Co photoanode reaches 4.97 mA cm−2, which is significantly greater than those of BiVO4/NFTA (4.36 mA cm−2), BiVO4/Co (2.51 mA cm−2), BiVO4 (1.34 mA cm−2), respectively. Detailed analysis confirms that NFTA could provide an efficient way to hasten the transfer of photo-generated holes on the photoanode surface and diminish the surface charge transfer resistance. In other hand, Co(OH)2 could be served as a cocatalyst to accelerate charge transfer for efficient oxygen evolution reaction as well as a protective layer to maintain the long-term stability of NFTA on the surface of BiVO4 during water oxidation. Such double oxygen evolution co-catalysts decoration strategy paves an effective pathway to enhance the PEC water oxidation performance of BiVO4 photoanode.

CoNi2S4 cocatalyst modified TiO2 nanorods/nanoflower homojunction for efficient photoelectrochemical water splitting

Photoelectrochemical water splitting is a promising green method for obtaining clean energy, and its core lies in the preparation of high-performance photoanodes. In this study, TiO2 nanorods/nanoflower homojunction photoanodes were prepared using a one-step hydrothermal method, unlike the complex material composite process used in most previous research works, the TiO2 homojunction photoanode obtained through a one-step method combines the advantages of nanorod and nanoflower structures. CoNi2S4 was further used as an oxygen evolution cocatalyst supported on the TiO2 nanorods/nanoflower homojunction photoanodes, enhancing oxygen evolution kinetics. The photogenerated current density of the obtained TiO2 flower-rod/CoNi2S4 composite photoanode at 1.23 V (versus RHE) was 1.64 mA cm−2, which is 2.3 times of that of TiO2 nanorod photoanode. By density function theory calculation, it is confirmed that the loading of CoNi2S4 cocatalyst can significantly reduce the overpotential and enhance the kinetic process of oxygen evolution reaction.

The CuSCN layer between BiVO4 and NiFeOx for facilitating photogenerated carrier transfer and water oxidation kinetics

Modification of oxygen evolution co-catalyst (OEC) on the surface of bismuth vanadate (BiVO4) can effectively improve the kinetics of water oxidation, but it is still limited by the small hole extraction driving force at the BiVO4/OEC interface. Modulating the BiVO4/OEC interface with a hole transfer layer (HTL) is expected to facilitate hole transport from BiVO4 to the OEC surface. Herein, a copper(I) thiocyanate (CuSCN) HTL is inserted between BiVO4 and NiFeOx OEC to create BiVO4/CuSCN/NiFeOx photoanode, resulting in a significant enhancement of photoelectrochemical (PEC) water splitting performance. From electrochemical analyses and density functional theory (DFT) simulations, the markedly enhanced PEC performance is attributed to the insertion of CuSCN as an HTL, which promotes the extraction of holes from BiVO4 surface and boosts the water oxidation kinetics. The optimal photoanode achieves a photocurrent density of 5.6 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (vs. RHE) and an impressive charge separation efficiency of 96.2 %. This work offers valuable insights into the development of advanced photoanodes for solar energy conversion and emphasizes the importance of selecting an appropriate HTL to mitigate recombination at the BiVO4/OEC interface.

Amorphous metal-organic frameworks loaded on BiVO4 photoanodes with unique internal metal-like structure for promoting photoelectrochemical water splitting

Although ferrocene (Fc) based Metal-Organic Frameworks (MOFs) can act as oxygen evolution co-catalysts (OECs) for improvement of catalytic reactivity, the poor conductivity and lack of highly active metal sites limit its further application in photoelectrochemical (PEC) water splitting. Herein, the amorphous NiFc-MOF was grafted on BiVO4 photoanode (BiVO4@aNiFc-MOFs) for efficient PEC water splitting. This novel BiVO4@aNiFc-MOFs exhibits high current density of 4.34 mA cm−2 at 1.23 VRHE and relative low onset potential of 0.223 VRHE. The subsequent characterizations demonstrate that Ni species with metal-like state in bulk of aNiFc-MOFs form strong metal-support interaction with BiVO4, thereby promoting the interfacial charge transfer. Moreover, the surface of aNiFc-MOFs is short-range ordered with abundant coordinatively unsaturated Ni sites, creating a more favorable pathway for oxygen evolution reaction from thermodynamics. This work provides a simple method to design photoanodes with efficient OECs of amorphous MOFs for feasible PEC water splitting application.

Ultrasound Induces Local Disorder of FeOOH on CdIn2S4 Photoanode for High Efficiency Photoelectrochemical Water Oxidation.

The regulation of the crystal structure of oxygen evolution cocatalyst (OEC) is a promising strategy for enhancing the photoelectrochemical efficiency of photoanodes. However, the prevailing regulating approach typically requires a multistep procedure, presenting a significant challenge for maintaining the structural integrity and performance of the photoanode. Herein, FeOOH with a local disordered structure is directly grown on a CdIn2S4 (CIS) photoanode via a simple and mild sonochemical approach. By modulating the localized supersaturation of Ni ions, ultrasonic cavitation induces Ni ions to participate in the nucleation and growth of FeOOH clusters to cause local disorder of FeOOH. Consequently, the local disordered FeOOH facilitates the exposure of additional active sites, boosting OER kinetics and extending charge carrier lifetimes. Finally, the optimal photoanode reaches 4.52mAcm-2 at 1.23VRHE, and the onset potential shifts negatively by 330mV, exhibiting excellent performance compared with that of other metal sulfide-based photoelectrodes reported thus far. This work provides a mild and controllable sonochemical method for regulating the phase structure of OECs to construct high-performance photoanodes.

Engineering heteropolyblue hole transfer layer for efficient photoelectrochemical water splitting of BiVO4 photoanodes

Constructing hole transport layer (HTL) has emerged as a forefront approach to enhance the efficiency of photoelectrochemical (PEC) water oxidation. Here, we introduce the concept of the heteropolyblue HTL as a solution to address the orientation anisotropy issue associated with traditional solid-phase HTL. Integrated with cobalt-based polyoxometalate oxygen evolution cocatalyst and BiVO4 substrate, a BiVO4/HPMo: Co photoanode was constructed, achieving a separation efficiency of 96% and a photocurrent density of 5.7 mA cm−2 at 1.23 V vs. RHE. Combined with the calculation results, we determined that the Mo6⁺/Mo5⁺ electron pair in heteropolyblue acts as a bridge for hole transport. The robust redox capabilities and electron-rich characteristics of heteropolyblue confer durability to the HTL and enable the continuous transport of holes, collectively expediting reaction kinetics. This work represents the initial exploration of the systematic integration of heteropolyblue with photoanodes, unveiling the considerable potential of heteropolyblue in PEC systems.

Engineering Surface Passivation and Hole Transport Layer on Hematite Photoanodes Enabling Robust Photoelectrocatalytic Water Oxidation.

Regulation of charge transport at the molecular level is essential to elucidating the kinetics of junction photoelectrodes across the heterointerface for photoelectrochemical (PEC) water oxidation. Herein, an integrated photoanode as the prototype was constructed by use of a 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin-cobalt molecule (CoTCPP) and ZnO on hematite (α-Fe2O3) photoanode. CoTCPP molecules serve as a typical hole transport layer (HTL), accelerating the transport of the photogenerated holes to oxygen evolution cocatalysts (OECs). Meanwhile, ZnO as the surface passivation layer (SPL) can passivate the interfacial state and reduce the level of electron leakage from hematite into the electrolyte. After the integration of OECs, the state-of-the-art α-Fe2O3/ZnO/CoTCPP/OECs photoanode exhibits a distinguished photocurrent density and excellent stability in comparison with pristine α-Fe2O3. The simultaneous incorporation of a ZnO and CoTCPP dual interlayer can effectively modulate the interfacial photoinduced charge transfer for PEC reaction. This work provides in-depth insights into interfacial charge transfer across junction electrodes and identifies the critical roles of solar PEC conversion.

Nonstoichiometric In–S group yielding efficient carrier transfer pathway in In2S3 photoanode for solar water oxidation

AbstractThe construction of high‐efficiency photoanodes is essential for developing outstanding photoelectrochemical (PEC) water splitting cells. Furthermore, insufficient carrier transport capabilities and sluggish surface water oxidation kinetics limit its application. Using a solvothermal annealing strategy, we prepared a nonstoichiometric In–S (NS) group on the surface of an In2S3 photoanode in situ and unexpectedly formed a type II transfer path of carrier, thereby reducing the interfacial recombination and promoting the bulk separation. First‐principles calculations and comprehensive characterizations demonstrated NS group as an excellent oxygen evolution cocatalyst (OEC) that effectively facilitated carrier transport, lowered the surface overpotential, increased the surface active site, and accelerated the surface oxygen evolution reaction kinetics by precisely altering the rate‐determining steps of * to *OH and *O to *OOH. These synergistic effects remarkably enhanced the PEC performance, with a high photocurrent density of 5.02 mA cm−2 at 1.23 V versus reversible hydrogen electrode and a negative shift in the onset potential by 310 mV. This work provides a new strategy for the in situ preparation of high‐efficiency OECs and provides ideas for constructing excellent carrier transfer and transport channels.

Synergistic Effect of Co3(HPO4)2(OH)2 Cocatalyst and Al2O3 Passivation Layer on BiVO4 Photoanode for Enhanced Photoelectrochemical Water Oxidation

Bismuth vanadate (BVO) is regarded as an exceptional photoanode material for photoelectrochemical (PEC) water splitting, but it is restricted by the severe photocorrosion and slow water oxidation kinetics. Herein, a synergistic strategy combined with a Co3(HPO4)2(OH)2 (CoPH) cocatalyst and an Al2O3 (ALO) passivation layer was proposed for enhanced PEC performance. The CoPH/ALO/BVO photoanode exhibits an impressive photocurrent density of 4.9 mA cm−2 at 1.23 VRHE and an applied bias photon-to-current efficiency (ABPE) of 1.47% at 0.76 VRHE. This outstanding PEC performance can be ascribed to the suppressed surface charge recombination, facilitated interfacial charge transfer, and accelerated water oxidation kinetics with the introduction of the CoPH cocatalyst and ALO passivation layer. This work provides a novel and synergistic approach to design an efficient and stable photoanode for PEC applications by combining an oxygen evolution cocatalyst and a passivation layer.

Rational design of ternary NiCoFe hydrotalcite nanosheet co-catalysts to enhance the photoelectrochemical performance of α-Fe2O3 photoelectrodes

The reasonable construction of oxygen evolution co-catalysts on semiconductors is an effective means to enhance the photoelectrocatalytic performance of photoelectrodes. In this work, NiCoFe-LDH nanosheets with trimetallic active sites were integrated into α-Fe2O3 photoelectrodes by hydrothermal method and cation exchange reaction method. The NiCoFe-LDH acts as an effective co-catalyst, which significantly reduces the onset potential of the photoelectrode and enhances its photocurrent and stability. The photocurrent density of α-Fe2O3/NiCoFe-LDH composite photoelectrode reaches 0.62 mA/cm2, which is 6.8 and 1.4 times that of pure α-Fe2O3 and α-Fe2O3/NiCo-LDH, respectively and its starting potential is reduced to 0.52 V. At the same time, the co-catalyst with ternary metals provides more active sites on the surface of the photoelectrode, promoting the migration of photogenerated holes to the solution and enhancing the rapid separation of carriers. In addition, the synergistic interaction between multivalent transition metal ions in LDH plays an important role in improving the photoelectrocatalytic performance of the photoelectrodes. The co-catalyst introduced in this paper is expected to enhance the intrinsic photoelectrochemical activity of other semiconductor photoelectrodes and further explore their applications in solar energy conversion.

Schiff Base Complex Cocatalyst with Coordinatively Unsaturated Cobalt Sites for Photoelectrochemical Water Oxidation.

Integrating inorganic oxygen evolution cocatalysts (OECs) with photoanodes is regarded as an available strategy to increase the photogenerated charge utilization for accelerated water oxidation kinetics. Nevertheless, most widely used transition metal (oxyhydr)oxides OECs suffer from inevitable charge recombination at photoanode/OECs interfaces and underabundant catalytic active sites. Herein, a cobalt-organic complex with microflower-like features (denoted as MF) was constructed by coordination of Schiff base ligands and Co2+ metal ions and then decorated on porous BiVO4 employed as photoanodes for photoelectrochemical (PEC) water oxidation. The as-synthesized BiVO4/MF photoanode achieves a photocurrent density of 4.38 mA cm-2 and at 1.23 VRHE in 0.5 M Na2SO4 electrolyte under simulated 1 sun illumination, over approximately 5.48 times larger than that of BiVO4 counterpart, and exhibits a 120 mV cathodic shift of onset potential with outstanding photostability. Systematic characterizations reveal that the improved PEC efficiency is mainly attributed to the well-designed coordinatively unsaturated Co2+ sites, which not only serve as powerful photohole extraction engines along reversed interfacial Co-O-Bi bonds to promote charge transfer across the BiVO4/complex interface but also act as reaction active centers by accelerating surface water oxidation kinetics. This work provides new insights for designing highly effective OECs for PEC water oxidation.

Exploring the impact of surface oxygen vacancies on charge carrier dynamics in BiVO4 photoanodes through atmospheric pressure plasma jet post-treatment for efficiency improvement in photoelectrochemical water oxidation

We have demonstrated the production of high-density surface oxygen vacancy (ovs) in BiVO4 (BVO) photoanodes through the post-treatment of an atmospheric pressure plasma jet (APPJ). The 3.4-fold enhancement of photocurrent density of BVO photoanodes at 1.23 VRHE for photoelectrochemical (PEC) water oxidation due to 95 % of charge transfer efficiency at the BVO/electrolyte interface. In-situ transient absorption spectroscopy investigations provided insights into the charge carrier dynamics of the APPJ-treated BVO photoanode, revealing that abundant electrons could effectively be trapped in the ovs states to prevent charge carrier recombination. NiOOH/FeOOH oxygen evolution co-catalyst was further decorated on the APPJ-treated BVO photoanode resulted in a remarkable photocurrent density of 3.6 mA/cm2 at 1.23 VRHE, an anodic bias photon-to-current efficiency of 1.4 % at 0.62 VRHE, and a faradaic efficiency over 90 % in PEC water splitting. Our study provides important and novel insights into the surface vacancy engineering of metal oxides for green hydrogen production.

In situ surface-enhanced infrared absorption analysis of the excited carrier transfer from n-type Si photoelectrode to Pt oxygen evolution cocatalyst by probing adsorbed CO molecules

BackgroundThe development of efficient photoelectrode material for water-splitting reactions has received considerable attention as it produces hydrogen gas from water using solar energy. Photoexcited holes migrate to the surface of an n-type photoelectrode oxidizing water to oxygen, and excited electrons migrate to the counter electrode reducing protons to hydrogen. However, there is limited knowledge of excited carrier transfer. MethodsTherefore, in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) has been used to investigate the excited hole migration from n-type Si photoelectrode to Pt oxygen evolution cocatalysts by monitoring the frequency of CO adsorbed on the Pt cocatalysts. Significant findingsAt the positive potential of Si photoelectrode under UV irradiation, the SEIRA spectrum of the CO adsorbed on the Pt cocatalyst shifted to higher wavenumbers owing to the excited hole transfer from n-type Si photoelectrode to the Pt cocatalyst attributed to band bending at the interface between the Si photoelectrode and Pt cocatalysts. It was successfully demonstrated that the regulation of photoexcited carriers was crucial for enhancing the photoelectrochemical activity of water splitting.

Cocatalysts-Photoanode Interface in Photoelectrochemical Water Splitting: Understanding and Insights.

Sluggish oxygen evolution reactions on photoanode surfaces severely limit the application of photoelectrochemical (PEC) water splitting. The loading of cocatalysts on photoanodes has been recognized as the simplest and most efficient optimization scheme, which can reduce the surface barrier, provide more active sites, and accelerate the surface catalytic reaction kinetics. Nevertheless, the introduction of cocatalysts inevitably generates interfaces between photoanodes and oxygen evolution cocatalysts (Ph/OEC), which causes severe interfacial recombination and hinders the carrier transfer. Recently, many researchers have focused on cocatalyst engineering, while few have investigated the effect of the Ph/OEC interface. Hence, to maximize the advantages of cocatalysts, interfacial problems for designing efficient cocatalysts are systematically introduced. In this review, the interrelationship between the Ph/OEC and PEC performance is classified and some methods for characterizing Ph/OEC interfaces are investigated. Additionally, common interfacial optimization strategies are summarized. This review details cocatalyst-design-based interfacial problems, provides ideas for designing efficient cocatalysts, and offers references for solving interfacial problems.

Nitrogen incorporated oxygen vacancy enriched MnCo2Ox/BiVO4 photoanodes for efficient and stable photoelectrochemical water splitting

Oxygen vacancies in oxygen evolution cocatalysts (OECs) can significantly improve the photoelectrochemical (PEC) water splitting performance of photoanodes. However, OECs with abundant oxygen vacancies have a poor stability when exposing to the highly-oxidizing photogenerated holes. Herein, we partly fill oxygen vacancies in a MnCo2Ox OEC with N atoms by a combined electrodeposition and sol-gel method, which dramatically improves both photocurrent density and stability of a BiVO4 photoanode. The optimized N filled oxygen vacancy-rich MnCo2Ox/BiVO4 photoanode (3 at.% of N) exhibits an outstanding photocurrent density of 6.5 mA·cm−2 at 1.23 VRHE under AM 1.5 G illumination (100 mW·cm−2), and an excellent stability of over 150 h. Systematic characterizations and theoretical calculations demonstrate that N atoms stabilize the defect structure and modulate the surface electron distribution, which significantly enhances the stability and further increases the photocurrent density. Meanwhile, other heteroatoms such as carbon, phosphorus, and sulfur are confirmed to have similar effects on improving PEC water splitting performance of photoanodes.