Novel Ag2S nanoparticles on reduced graphene oxide sheets as a super-efficient catalyst for the reduction of 4-nitrophenol

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（δ^＋）,with pendant base S（δ） 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.