Cascaded multiple-step hole transfer for enhancing photoelectrochemical water splitting

Serious surface recombination and sluggish reaction kinetics hamper the photoelectrochemical (PEC) performance from being efficient. Although coupling oxygen evolution catalysts on photoanodes to accelerate electrode reactions has been demonstrated an effective strategy to enhance photocurrent, the surface recombination still limits the performance to an ideal level. Herein, a novel multi-step hole transfer strategy is developed for accelerating hole transport and thus suppressing the surface recombination. In this system, porphyrin and polyaniline both act as hole transfer layers, which construct an effective stair-stepping hole transfer channel to ensure much more holes take part in water oxidation process. This simple interface modulation system exhibits a remarkable photocurrent of 4.5 mA cm⁻² at 1.23 V (vs. reversible hydrogen electrode (RHE), AM 1.5 G illumination) accompanied with good stability and provides a promising strategy for the design of efficient photoanodes for solar conversion.