▎ 摘　　要

Here, Ag2S nanoparticles on reduced graphene oxide (Ag2S NPs/RGO) nanocomposites with relatively good distribution are synthesized for the first time by conversing Ag NPs/RGO to Ag2S NPs/RGO via a facile hydrothermal sulfurization method. As an noval catalyst for the reduction of 4-nitrophenol (4-NP), it only takes 5 min for Ag2S NPs/RGO to reduce 98% of 4-NP, and the rate constant of the composites is almost 13 times higher than that of Ag NPs/RGO composites. The high catalytic activity of Ag2S NPs/RGO can be attributed to the following three reasons: (1) Like metal complex catalysts, the Ag2S NPs is also rich with metal center Ag (r), with pendant base S (S-) close to it, and thus the Ag and basic S function as the electron-acceptor and proton-acceptor centers, respectively, which facilitates the catalyst reaction; (2) RGO features the high adsorption ability toward 4-NP which provides a high cOncentration of 4-NP near the Ag2S NPs; and (3) electron transfer from RGO to Ag2S NPs, facilitating the uptake of electrons by 4-NP molecules. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.