Unlocking the Potential of Photoelectrochemical Water Splitting via Heterointerface Charge Polarization

The coupling of semiconductor (SC) and transition metal oxyhydroxide (TMOOH) is a promising approach for solar fuel production. However, the inevitable interfacial charge recombination and sluggish oxygen evolution reactions severely hinder the application of photoelectrochemical (PEC) device. This study demonstrates an innovative charge polarization strategy that simultaneously enhances both long-range charge transfer and surface catalytic reaction dynamics through the rational construction of CoO_x/MnO_x heterointerface in SC/TMOOH system. Kelvin probe force microscopy, in situ ultraviolet/visible spectroelectrochemistry, and density functional theory calculations indicate that the tunable charge polarization of Co^δ- and Mn^δ+ can affect influences the SC/TMOOH and TMOOH/electrolyte interfaces, primarily through inducing the accelerated charge transfer dynamics (K_h) and diminishing the adsorption of oxygen-containing intermediates. As anticipated, the BiVO₄/CoO_x/MnO_x/FeNiOOH exhibits an impressive photocurrent of 6.75 mA cm^-2 at 1.23 V_RHE, along with a superior photostability. Furthermore, the smart approach can also be harnessed in the BiVO₄/CoO_x/CeO_x/FeNiOOH photoanode. This study provides a novel polarization strategy for the design of optimal photoanodes for PEC water splitting.