Efficient Strategy for Boosting the Solar-Driven Water Oxidation of the BiVO 4 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 BiVO 4 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 BiVO 4 photoanode. Under simulated sunlight (AM1.5G) illumination, the designed NiCo-LDH/CuPc/BiVO 4 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 BiVO 4 photoanode, respectively. The significantly improved PEC performance in the low bias range mirrors that the decorated NiCo-LDH/CuPc layers on BiVO 4 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.