Organic-inorganic p-type PEDOT:PSS/CuO/MoS2 photocathode with in-built antipodal photogenerated holes and electrons transfer pathways for efficient solar-driven photoelectrochemical water splitting

Organic PEDOT:PSS thin film and n-type MoS2 flakes were incorporated on CuO photocathode as the underlying layer and surface co-catalysts, respectively, establishing a rationally-designed novel integrated structure of PEDOT:PSS/CuO/MoS2. The organic-inorganic interface of PEDOT:PSS/CuO effectively shuttles photogenerated holes towards the FTO/PEDOT:PSS junction. Furthermore, the surface MoS2 co-catalysts form a p-n junction with CuO, which accelerates the transport of photogenerated electrons towards the photocathode/electrolyte junc-tion, in addition to providing more reactive sites for the H2 evolution reaction. These synergistically formed antipodal charge transfer pathways have led to improved charge separation, rapid interfacial charge transfer kinetics and impeded electron-hole recombination in the PEDOT:PSS/CuO/MoS2 photocathode, which can achieve a photocurrent density of - 2.26 mA/cm2 at-0.6 V vs Ag/AgCl (2.1 times higher than that of the bare CuO photocathode). Analytical characterisations, electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy (IMPS), also provide supporting evidence for its dramatically enhanced PEC water splitting performance.