Super-hydrophilic BiVO4/MgO/FeCo2O4 charge migration achieves efficient photoelectrochemical performance

To address the issue of inefficient charge transfer efficiency at the semiconductor/cocatalyst interface, we engineered a BiVO 4 /MgO/FeCo 2 O 4 array, incorporating a MgO interlayer. This design aimed to enhance the performance of photoelectrochemical (PEC) water splitting on BiVO 4 and FeCo 2 O 4 . The introduced interlayer efficiently hinders hole backflow, promoting unimpeded charge migration within the multi-hybrid structure. This, in turn, significantly reduces the recombination of electron-hole pairs. In addition, the BiVO 4 /MgO/FeCo 2 O 4 undergoes a low-temperature plasma treatment, resulting in super-hydrophilicity. This treatment enhances charge migration efficiency and fosters extensive contact between the electrolyte and electrode interfaces. Photoelectrochemical analysis demonstrates that H-BiVO 4 /MgO/FeCo 2 O 4 exhibits exceptional performance for the oxygen evolution reaction (OER), showcasing a photocurrent density of 4.3 mA·cm −2 at 1.23 V vs. RHE in 0.5 M Na 2 SO 4 under AM 1.5 G (100 mW·cm −2 ) illumination. Remarkably, this value is 5.2 times higher than that observed for BiVO 4 . Furthermore, the maximum incident photon to current conversion efficiency (IPCE) reaches an impressive 61.7 %, surpassing that of BiVO 4 and BiVO 4 /FeCo 2 O 4 by approximately 5.1 and 1.7 times, respectively. Additionally, the charge separation efficiency of H-BiVO 4 /MgO/FeCo 2 O 4 achieves a notable 83.4 %, and the charge injection efficiency is substantially improved. This study advocates for a straightforward yet highly effective approach to mitigate interfacial electron-hole recombination.