Boosting photoelectrochemical water oxidation by sandwiching gold nanoparticles between BiVO4 and NiFeOOH.

BiVO₄ is one of the promising photoanodes for water oxidation, while its efficiency is much lower than the theoretical value because of the rapid recombination rate and low activity for the oxygen evolution reaction (OER). Herein, a BiVO₄/Au/NiFeOOH sandwich structure is constructed for enhanced PEC water oxidation. In comparison with BiVO₄/NiFeOOH, the incorporation of Au nanoparticles (NPs) can further enhance the PEC performance toward water oxidation. The BiVO₄/Au/NiFeOOH photoanode exhibits a photocurrent density of 5.3 mA cm⁻² at 1.23 V, which is 3.47 times that of BiVO₄. Systematic experimental and theoretical studies indicate that Au NPs enhance the PEC water oxidation through the generation of hot holes through an interband transition, improving the photocarrier separation, and enhancing the water oxidation activity of NiFeOOH. This work not only provides a new way for the fabrication of highly efficient photoanodes for water oxidation, but also deepens the understanding of the role of Au NPs in promoting PEC water splitting. [ABSTRACT FROM AUTHOR]