NiO/Poly(4-alkylthiazole)s Hybrid Interface for Promoting Spatial Charge Separation in Photoelectrochemical Water Reduction.

Conjugated polymers are emerging as alternatives to inorganic semiconductors for the photoelectrochemical (PEC) water splitting. Herein, semitransparent poly(4-alkylthiazole)s layers with different trialkylsilyloxymethyl (RSiOCH-) side-chains (PTzTNB: R = -butyl, PTzTHX: R = -hexyl) are applied to functionalize NiO thin films to build hybrid photocathodes. The hybrid interface allows the effective spatial separation of the photoexcited carriers. Specifically, the PTzTHX-deposited composite photocathode increases the photocurrent density sixfold and twofold at 0 V vs. reversible hydrogen electrode (RHE) in comparison to the pristine NiO and PTzTHX photocathodes, respec-tively. This is also reflected in the substantial anodic shift of onset potential under simulated Air Mass 1.5 Global (AM 1.5G) illumination owing to the prolonged lifetime, augmented density and alleviated recombination of photogenerated electrons. Additionally, coupling the inorganic and organic components also enhances the photoabsorption and amends the stability of the photocathode-driven system. This work demonstrates the feasibility of the poly(4-alkylthiazole)s as an effective alternative to known inorganic semiconductor materials. We highlight the interface alignment for polymer-based photoelectrodes.