Lattice Distortion Promotes Carrier Separation to Improve the Photoelectrochemical Water Splitting Performance of Bismuth Vanadate Photoanode

Abstract The poor carrier separation capability and sluggish water oxidation reaction kinetics are two critical factors that impact the photoelectrochemical (PEC) water splitting performance of the bismuth vanadate (BiVO₄) photoanode. Previous studies have demonstrated that doping with rare‐earth elements to induce lattice distortions and loading oxygen evolution reaction (OER) co‐catalysts are effective strategies for enhancing carrier separation capabilities and accelerating the kinetics of the water oxidation reaction. Herein, Cu²⁺‐doped RuO₂ (Cu‐RuO₂) particles are anchored onto rare earth element Thulium (Tm)‐doped BiVO₄ (Tm‐BiVO₄) photoanode substrates, constructing an integrated Cu‐RuO₂‐Tm‐BiVO₄ photoanode. The newly integrated photoanode not only achieves a photocurrent density of 5.3 mA cm⁻² at 1.23 V versus a reversible hydrogen electrode (vs RHE), but also exhibits exceptional stability. A series of detailed physical and chemical characterizations as well as density‐functional theory (DFT) calculations demonstrate that Tm doping induces lattice distortion in BiVO₄, enhancing the internal electric field and thereby facilitating carrier separation. Moreover, the anchored Cu‐RuO₂ particles not only lattice‐match with the Tm‐BiVO₄ photoanode, reducing interfacial transfer resistance, but also expedite the kinetics of the water oxidation reaction. The profound significance of this work is that it offers a reference for the future design and fabrication of novel integrated photoanodes.