Insight into interface charge regulation through the change of the electrolyte temperature toward enhancing photoelectrochemical water oxidation

The desired photoelectrochemical performance can be achieved by temperature regulation, but the nature for this improvement remains a controversial topic. Herein, we employed BiVO₄/CoO_x as a typical model system, and explored the fate of photogenerated holes at the different interfaces among BiVO₄/CoO_x/electrolyte by means of intensity modulated photocurrent spectroscopy (IMPS), scanning photoelectrochemical microscopy (SPECM) and traditional electrocatalysis characterization methods. Systematic quantitative analysis of the kinetics of photogenerated holes transfer at the BiVO₄/CoO_x interface under illumination and surface water oxidation at the CoO_x/electrolyte interface in the dark indicates that increasing temperature could not only enhance the surface catalytic reaction kinetics but also facilitate the interfacial charge transfer. As expected, the integrated system exhibited a remarkable photocurrent density of 3.6 mA cm⁻² (1.23 V_RHE, AM 1.5G, 45 °C), which is approximately 2.1 times higher than that of BiVO₄/CoO_x (15 °C). This work provides a promising strategy for achieving efficient photoelectrochemical water splitting.