Three-Dimensional Decoupling Co-Catalyst from a Photoabsorbing Semiconductor as a New Strategy To Boost Photoelectrochemical Water Splitting.

A cocatalyst is normally deposited on a photoabsorbing semiconductor (PAS) for photoelectrochemical (PEC) water splitting, but with drawbacks of limited loading, reduced light absorption, and tendency of charge recombination. To tackle these problems, a scheme of three-dimensional (3D) decoupling cocatalysts from the PAS with a pore-spanning crisscross conducting polymer host is proposed in this work. To demonstrate the concept, a facile method was developed for the in situ cogrowth of FeO x nanoparticles and conducting polymer (CP) network in various PAS with different microstructures such as a TiO2 nanorod array, WO3 nanosheet array, and planar TiO2 nanoparticle film, generating the bespoke photoanodes. The as-synthesized photoanodes exhibited a significantly enhanced PEC water splitting performance, which is clearly shown to arise from the improved light utilization, increased catalytic active sites, enhanced charge separation, and decreased electrochemical impedance of the photoelectrode. This 3D decoupling strategy is expected to open a promising direction for designing efficient PEC cells.