Unveiling the Activity and Stability Origin of BiVO₄ Photoanodes with FeNi Oxyhydroxides for Oxygen Evolution

Abstract

Understanding the origin of formation and active sites of oxygen evolution reaction (OER) cocatalysts is highly required for solar photoelectrochemical (PEC) devices that generate hydrogen efficiently from water. Herein, we employed a simple pH‐modulated method for in situ growth of FeNi oxyhydroxide ultrathin layers on BiVO4 photoanodes, resulting in one of the highest currently known PEC activities of 5.8 mA cm−2 (1.23 VRHE, AM 1.5 G) accompanied with an excellent stability. More importantly, both comparative experiments and density functional theory (DFT) studies clearly reveal that the selective formation of Bi−O−Fe interfacial bonds mainly contributes the enhanced OER activities, while the construction of V−O−Ni interfacial bonds effectively restrains the dissolution of V5+ ions and promotes the OER stability. Thereby, the synergy between iron and nickel of FeNi oxyhydroxides significantly improved the PEC water oxidation properties of BiVO4 photoanodes.

Engineering Nanostructure–Interface of Photoanode Materials Toward Photoelectrochemical Water Oxidation

“…[255] Through density functional theory calculations and experimental studies, it showed that the doping of Fe atoms into the lattice of CoO x produced abundant oxygen vacancies, which significantly improved the interfacial hole injection property of BiVO 4 and reduced the OER onset potential (Figure 19d). Recently, many other advanced co-catalysts have been demonstrated with outstanding performance and stability, such as natural polyphenols/Fe ion, [256] Cu porphyrin, [257] Fe-based (Ni 1−x Fe x and Co 1−x Fe x ) layered double hydroxide, [258][259][260][261] InPO x , [86] molecular Co Cubane, [262] MnO 2 , [263][264][265] and Co 8 -polyoxometalates. [266] In Table 4, it can be seen that by modifying pristine semiconductors with co-catalyst, boosted PEC performance can be achieved due to the significantly enhanced interfacial hole-injection efficiency.…”

Plasmon‐Enhanced Charge Separation and Surface Reactions Based on Ag‐Loaded Transition‐Metal Hydroxide for Photoelectrochemical Water Oxidation

“…As can be seen in Figure S4, Supporting Information, BV film belongs to monoclinic structure (PDF#14-0688), [23] which is in accordance with previous reports. [18,22] The Raman peaks of BV are located at 210.0, 324.0, 366.0, 640.0, 710.0 and 826.0 cm −1 (Figure S5, Supporting Information), meaning that the BV films have been successfully synthesized. [24] Subsequently, the ultrathin amorphous Co(OH) 2 (Figure S6, Supporting Information) nanosheets were uniformly electrodeposited on BV photoanodes (named as BV/Co(OH) 2 ).…”

“…From Figure S10b,c, Supporting Information, the Bi 4f and V 2P peaks are consistent with values reported previously. [18,22] The high-resolution Co 2p of BV/Co(OH) x -Ag can yield two spin-orbit doublets. The two peaks at 781.8 and 797.7 eV are generated by Co 2+ and another two peaks at 780.2 and 795.3 eV are ascribed to Co 3+ (Figure S11a, Supporting Information).…”

Stable Unbiased Photo‐Electrochemical Overall Water Splitting Exceeding 3% Efficiency via Covalent Triazine Framework/Metal Oxide Hybrid Photoelectrodes

“…[ 6,7 ] Cost‐competitive metal oxide semiconductors such as Cu 2 O, BiVO 4 , and Fe 2 O 3 are intriguing selections due to their high abundance and easy processability. [ 8–12 ] Nevertheless, oxide‐based photoelectrodes still exhibit low photocatalytic efficiency and poor stability in aqueous electrolytes, limiting their practical applications. [ 13–15 ]…”