Cascaded multiple-step hole transfer for enhancing photoelectrochemical water splitting.

Taking porphyrin and polyaniline as hole transfer layers simultaneously between BV and OEC, a novel multi-step hole transfer strategy was proposed to enhance PEC water splitting. The constructed system can effectively accelerate hole transport kinetics and suppress the interface recombination of charge carriers, resulting in a high PEC performance. [Display omitted] • A novel strategy was proposed to accelerate hole transport and suppress interface recombination. • BV/CoPy/PANI/CoFe photoanode exhibited excellent water oxidation capability. • The photocurrent of BV/CoPy/PANI/CoFe is 4.5 mA cm−2 at 1.23 V RHE under AM 1.5 G illumination. • IMPS and SPECM measurements revealed the mechanism of charge transfer kinetics. • This work provides an effective guideline for designing excellent photoanodes. 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. [ABSTRACT FROM AUTHOR]