Abstract Efficient charge separation is pivotal for enhancing the photoconversion efficiency in photoelectrochemical (PEC) water splitting. In this work, a heterojunction‐type electrode composed of Mo‐doped WO 3 integrated with InVO 4 was constructed. By employing a synergistic strategy that combines elemental doping with heterojunction engineering, the PEC performance was significantly enhanced. Both experimental characterizations and DFT calculations demonstrate that Mo doping modulates the electronic structure of WO 3 , reduces the energy barrier for oxygen vacancy formation, establishes efficient charge transport pathways across the semiconductor interface, and facilitates hole transfer with lowered energy barriers. The formation of a type‐II heterojunction (staggered gap heterojunction) between WO 3 and InVO 4 promotes spatial separation of photogenerated carriers via favourable band alignment, thereby further suppressing charge recombination. This was confirmed by a combination of UV–Vis DRS, photoluminescence spectroscopy, and transient photocurrent measurements, which collectively demonstrated an expanded light absorption range, significantly reduced electron–hole recombination, and improved charge separation efficiency. Owing to these synergistic effects, the Mo‐WO 3 /InVO 4 composite electrode exhibits excellent performance in a 0.5 M Na 2 SO 4 electrolyte, delivering a current density of 2.8 mA cm −2 at 1.23 V versus RHE. This value is approximately ten times higher than that of pure WO 3 and about twice that of the WO 3 /InVO 4 anode, respectively. The incident photon‐to‐current efficiency reaches a maximum exceeding 70% within the 300–500 nm spectral range, along with sustained operational stability for over 24 h. This study offers a valuable strategy for the rational design of highly efficient PEC water‐splitting systems.
Guo et al. (2026) studied this question.