Efficient Strategy for Boosting the Solar-Driven Water Oxidation of the BiVO4 Photoanode by Using a CuPc Derivative as a Hole Transport Highway

The decoration of an oxygen evolution cocatalyst (OEC) on a semiconductor photoanode can accelerate the sluggish kinetics of the oxygen evolution reaction (OER), but the severe charge recombination at the semiconductor/OEC interface hampers the photoelectrochemical (PEC) water splitting from being efficient. In this study, a tert-butyl substituted copper phthalocyanine (CuPc) ultrathin layer is introduced at the interface of a BiVO4 film and a NiCo-layered double hydroxide (NiCo-LDH) OEC layer as a hole transport highway to promote the extraction and transport of photoinduced holes and inhibit the charge recombination for improving the PEC water splitting performance of the BiVO4 photoanode. Under simulated sunlight (AM1.5G) illumination, the designed NiCo-LDH/CuPc/BiVO4 photoanode delivers a high applied bias photon-to-current efficiency (ABPE) of 1.28% at a low bias of 0.67 V vs. reversible hydrogen electrode (RHE), and the photocurrent density increases to 2.36 mA cm(-2) (at 0.67 V vs. RHE) and 4.03 mA cm(-2) (at 1.23 V vs. RHE), which is 7.8 and 3.4 times higher than that of the single BiVO4 photoanode, respectively. The significantly improved PEC performance in the low bias range mirrors that the decorated NiCo-LDH/CuPc layers on BiVO4 film can effectively reduce the energy barrier for the water oxidation. This research provides a promising strategy for improving solar-driven water oxidation by introducing an efficient hole transport layer (HTL) at the semiconductor/OEC interface and expands the design idea of PEC water splitting devices.