A novel BiVO4/P3HT photoanode for highly efficient water oxidation and its hole energy offset effect with CuPc derivative

BiVO4 has attracted extensive attention as photoanode material for photoelectrochemical (PEC) water splitting due to its suitable energy band structure and stability, but the poor charge mobility and sluggish oxygen evolution reaction (OER) kinetics restrict its practical application seriously. Herein, an intrinsic p-type poly(3-hexylthiophene) (P3HT) is used as hole transport layer (HTL) for the first time to unleash the potential of BiVO4(BV)/NiCo-layered double hydroxide(LDH) photoanode. Furthermore, tetra-tert-butyl substituted copper(Ⅱ) phthalocyanine (CuPc) derivative as dopant is introduced into the P3HT HTL to compensate the energy loss of photogenerated holes in the BV/P3HT/LDH photoanode. Benefitted from the modulated HTL, the prepared BV/P3HT-CuPc/LDH photoanode exhibits a superior photocurrent density of 5.54 mA cm−2 at 1.23 V vs. RHE with hole scavenger and 4.25 mA cm−2 in borate buffer electrolyte. The built-in potential formed at the interface of BiVO4 film and P3HT HTL is beneficial for rapid hole extraction and transfer, while the doped CuPc induces outward driving force for the photoinduced holes to participate in OER more efficiently. This work provides a pioneering view for designing energy band matched HTL by considering charge transport and charge energy to balance the transfer efficiency in bulk and at solid/liquid interface of photoanode for water splitting.