Surface-Plasmon-Resonance-Induced Photocatalysis by Core-Shell SiO2@Ag NCs@Ag3PO4 toward Water-Splitting and Phenol Oxidation Reactions.

Abstract

A series of core-shell-structured SiO2@Ag NCs@Ag3PO4 photocatalysts with varying percentages of silver nanoclusters (Ag NCs) have been synthesized by using SiO2 as a core material. The crystal structure, morphology, chemical composition, and photophysical properties of as-synthesized materials have been thoroughly analyzed through powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse-reflectance spectroscopy, and photoluminescence (PL) spectroscopy techniques. The introduction of Ag NCs has effectively reduced the photogenerated electron-hole recombination rate, as evidenced from PL and Nyquist plots. The electrochemical properties of the photocatalysts were studied through photocurrent measurement, and 23-fold current enhancements in the cathodic direction are observed. The excellent current enhancement by the photocatalyst is attributed to the presence of Ag NCs. The effectiveness of the photocatalysts toward photocatalytic water splitting was studied and produced 2460 μmol h-1 g-1 hydrogen and 1236 μmol h-1 g-1 oxygen by 2 wt % loaded Ag NCs. Again the photocatalytic phenol oxidation has been explored, and the best catalyst is able to oxidize 91% phenol upon visible-light irradiation. The photocatalyst having 2 wt % Ag NCs shows better activity toward both water splitting and phenol oxidation compared to others, which is attributed to better visible-light absorption efficiency, lower electron-hole recombination rate, and low interfacial charge-transfer resistance.