A three-dimensional TiO2@Bi2MoO6 heterojunction array as photoanode for efficient photoelectrochemical water splitting

Abstract

A three-dimensional (3D) TiO₂@Bi₂MoO₆ heterojunction array was successfully fabricated through the in situ growth of aligned Bi₂MoO₆ nanosheets (NSs) on highly ordered TiO₂ nanorod (NR) arrays. The synthesized type-II band-aligned heterostructure exhibits extended light absorption, a significantly enlarged active surface area, and remarkably improved charge separation efficiency, leading to exceptional photoelectrochemical (PEC) performance. The optimized TiO₂@Bi₂MoO₆ (TiO₂–0.8Bi) photoanode achieves an outstanding photocurrent density of 3.7 mA cm⁻² at 1.23 V vs. RHE, representing a 4.6-fold enhancement compared to pristine TiO₂. Furthermore, the heterostructure demonstrates a maximum incident photon-to-current conversion efficiency (IPCE) of 71.4 ± 0.7% at ∼380 nm, which is approximately 2.5 times higher than that of pure-phase TiO₂ NR arrays (31.2%). These superior PEC properties are attributed to the synergistic effects of enhanced light harvesting, efficient interfacial charge transfer, and suppressed carrier recombination. This work provides a promising strategy for designing high-performance heterojunction-based photoanodes for solar energy conversion applications.