Structural tuning of BiVO4/MnFe-MOF photoanodes boosts hole extraction for photoelectrochemical water splitting

Abstract

To achieve extremely effective photoelectrochemical (PEC) water splitting, it is imperative to suppress charge recombination at the interfaces between the oxygen evolution cocatalyst (OEC) and BiVO₄. In view of this, a robust interfacial interaction between BiVO₄ and MnFe-MOF was successfully established, and the optimized BiVO₄/MnFe-MOF photoanode exhibits a photocurrent density of 3.64 mA cm⁻² at 1.23 V versus the reversible hydrogen electrode (RHE) under AM 1.5 G illumination (100 mW cm⁻²). Owing to the robust metal–support interaction (SMSI) between BiVO₄ and MnFe-MOF, the electron transfer from Bi/V to MnFe-MOF leads to the formation of Bi/V–O–Mn/Fe chemical bonds and electron-rich Fe species (Fe²⁺), which readily provide an extra driving force for the extraction of the photogenerated holes from BiVO₄ to MnFe-MOF. Furthermore, the introduction of Mn atoms regulates the electronic structure of Fe sites in MnFe-MOF, thus accelerating the kinetics of surface water oxidation. This work sheds light on the function of the interface and active site electronic structure modulation of photoelectrodes for sustainable solar energy conversion.