High-Performance Natural-Sunlight-Driven Ag/AgCl Photocatalysts with a Cube-Like Morphology and Blunt Edges via a Bola-Type Surfactant-Assisted Synthesis
Ag/AgCl-based structures have recently been receiving considerable attention as visible-light-driven plasmonic photocatalysts, wherein those shaped with an anisotropic morphology are considered to be an efficient way to enhance their performances. While the past decade has witnessed great progresses in this direction, it is still strongly desired to initiate a green and low-cost protocol for shaped Ag/AgCl of high catalytic activity. By a surfactant-assisted synthesis protocol, wherein a cationic bola-type surfactant of chloride counteranions serves both as reactant (namely, source of chlorine) for the generation of AgCl structures and as directing template to assist the formation of anisotropically shaped structures, we herein report that cube-like Ag/AgCl with blunt edges could be fabricated simply by dropping an aqueous solution of silver nitrate into an ethanol solution of hexane-1,6-bis(trimethylammonium chloride) surfactant. Importantly, compared to the sphere-like counterparts manufactured using conventional tadpole surfactant, the as-fabricated cube-like structures exhibit substantially boosted catalytic performances under visible-light or natural-sunlight irradiations. It has been revealed that photogenerated holes might serve as the main active species during the catalytic process. Meanwhile, our results have disclosed that in contrast to the sphere-like Ag/AgCl structures, thus-constucted cube-like structures are relatively enriched with high-index AgCl facets of lighter hole effective mass, which promotes a faster carrier transfer, facilitates the migration of the photogenerated holes to the surface to be involved in photocatalytic reaction, and suppresses carrier recombination, leading to their enhanced photocatalytic performances. Considering the tremendous diversity of surfactants (bola-, gemini-, polymeric surfactants etc.) with various halide counteranions and their sophisticated template effects, our new strategy might inaugurate new opportunities for silver/silver halide (Ag/AgX, X= Cl, Br, I)-based plasmonic structures with various shaped architectures and with superior light-to-chemical energy conversion capability.