Bioinspired electron carrier mediated transmembrane photocatalytic hydrogen evolution in silica colloidosomes†

Abstract

Inspired by the ordered processes of chloroplasts in photosynthesis involving coordinative linkages and efficient compartmentalization, a bioinspired compartmentalized photocatalytic system (BCPS) with an inorganic compartment is designed for photocatalytic hydrogen evolution with light driven electron carrier mediated cross-membrane energy transport. A typical BCPS comprises silica colloidosomes containing co-catalysts as microreactors, where positively charged N-methyl-4-cyanopyridinium (MCP⁺) serves as the electron carrier. The MCP⁺ molecules harvest energy from photoexcited g-C₃N₄, and transit to electrically neutral species MCP⁰, which can pass the colloidosome. Driven by light, the MCP⁰ diffuse across the membrane and transport electrons to H⁺ for hydrogen evolution, in which Pt particles are employed as co-catalysts. Analogous to natural photosynthesis, hydrogen evolution occurs within compartments, separating light and dark reactions, protecting the dark reaction from interference during light harvesting and minimizing potential side effects. The system enables sustained evolution of hydrogen with a higher yield than that with the control catalysis in a bulk catalyst suspension. The dramatic influence of SDS on the hydrogen evolution was revealed, and a possible mechanism of electron carrier amount buffering was proposed.