Interfacial phosphate-like “bridge” mediates bulk charge and surface oxygenated-intermediate migration for efficient photoelectrochemical water splitting

Abstract

Regulating the heterointerface structure is a great challenge to developing an efficient photoelectrode for solar water splitting. Herein, the interfacial phosphate ([PO]) was brought into the ZnIn₂S₄/CdS interface to modulate the energy band structure by in situ exchange strategy. The interfacial [PO] paved an electronic “bridge” to eliminate the multiphase thermal resistance and promoted the oxygenated-intermediate migration for the surface oxygen evolution reaction (OER). The optimized ZnIn₂S₄–PO/CdS (ZIS–P/CdS) photoanode presented a prominent PEC activity with a maximum photocurrent density of 5.19 mA cm⁻² at 1.23 V vs. reversible hydrogen electrode (RHE) under AM 1.5 G illumination in a neutral solution without a sacrificial agent, which is about 9.8 times higher than that of the pristine ZnIn₂S₄ (0.53 mA cm⁻²). Furthermore, the oxygen output of ZIS–P/CdS was as high as 13.1 μmol within 3 h in the neutral solution. The in situ ultrafast spectroscopy and density functional theory simulation confirmed the [PO] promotion of the Z-scheme charge transfer and acceleration of the O–H bond breakage for OER. This work provides a new horizon for understanding the interface structure on the bulk charge migration and the surface reaction kinetics during the PEC reactions.