Non-conjugated polymer regulated photoelectrochemical water oxidation

Abstract

Co-catalyst engineering has significantly bolstered the tunable photoinduced charge migration/separation in solar-driven photoelectrochemical (PEC) technology, but intricate synthesis procedures, unfavorable long-term stability, high cost, and difficult interface configuration modulation retard the exploration of robust, stable, easily accessible, novel and highly efficient artificial photosystems. Herein, we conceptually unravel that a solid non-conjugated insulating polymer of poly(allylamine hydrochloride) (PAH) is able to function as an ideal interfacial co-catalyst to accelerate the charge separation of metal oxide (MO) substrates. In contrast to the conventional cognition that solid non-conjugated polymers in principle cannot participate in the charge transfer process owing to the deficiency of delocalized π electrons along the molecular framework, we have ascertained that non-conjugated PAH layer-by-layer self-assembled on the MOs effectively enables efficacious extraction of holes accumulating on the MOs/(PAH)_n heterostructured photoanodes to boost solar water oxidation, thereby substantially suppressing the charge recombination and prolonging the charge lifetime. Moreover, the crucial impacts of PAH on the interfacial charge transport kinetics, efficiency, and mechanism together with the origin of insulating polymer mediated carrier trapping sites are comprehensively probed. Our work would attract enduring interest in exploring insulating polymer co-catalysts to advance solar energy conversion.