Sub‐10‐nm Ag/AgX (X = Br,Cl) Nanoparticles: Superior Visible‐Light‐Driven Plasmonic Photocatalysts

While the past decade has witnessed great successes in silver/silver halide-based (Ag/AgX, X = Cl,Br) plasmonic photocatalysts, a facile fabrication of ultrafine Ag/AgX nanoparticles (NPs), which is recognized to be an efficient avenue for boosted catalytic performances, still remains a formidable challenge. Ultrasmall sub-10-nm Ag/AgX, which are discretely distributed on graphene oxide (GO, sub10-Ag/AgX/GO), can be easily fabricated by an oxidation–halogenation treatment of Ag/GO precursors of sub-10-nm AgNPs (sub10-Ag/GO). Significantly, compared to Ag/AgCl/GO and Ag/AgBr/GO of hundred-nanometer-sized Ag/AgX, the sub10-Ag/AgCl/GO and sub10-Ag/AgBr/GO display substantially enhanced photocatalytic activity by a factor of ≈16.4 and 38.2 times, respectively, despite their inconspicuous visible-light absorptions. The ultrafine size of the sub10-Ag/AgX and their grafting on but not being enwrapped by GO, which cooperatively facilitate a superior spatial separation capability of photogenerated electrons and holes, a satisfactory accessibility/availability of the abundantly exposed active sites, and consequently promote a more efficient utilization of photogenerated charge carriers, play important roles in their superior catalytic activities. The investigation initiates a new way for ultrafine Ag-based nanocomposites, and by a simple treatment of chemically modifiable ultrasmall-sized precursors, it provides new clues for other desired ultrafine-sized advanced nanomaterials that are difficult to synthesize via conventional protocols.