Ultrafast synthesis of multi-branched Au/Ag bimetallic nanoparticles at room temperature for photothermal reduction of 4-nitrophenol.

[Display omitted] • Based on the synergistic effect between Au and Ag elements, Au/Ag bimetallic nanoparticles usually possess unique localized surface plasmon resonance absorption from visible to near-infrared spectral regions, which lead to a superior photocatalytic activity for the degradation of many organic pollutants. • The ultrafast synthesis of multi-branched Au/Ag bimetallic nanoparticles is at room temperature using tannic acid as both reducing and capping agent. • The catalytic rate constant and TOF value are 0.13 s−1 and 1.33 s−1, respectively, when Au/Ag bimetallic nanoparticles are used as a catalyst to catalyst the reduction of p-nitrophenol under 808 nm laser irradiation. • The catalytic activity of Au/Ag bimetallic nanoparticles is higher than that of most previously reported Au, Ag or Au/Ag based catalysts. We report the ultrafast synthesis of multi-branched Au/Ag bimetallic nanoparticles (BMNPs) at room temperature using tannic acid (TA) as both reducing and capping agent. Based on the UV–Vis, TEM, HR-TEM, XRD and SAED analyses, the structure and absorption properties of Au/Ag BMNPs were realized. The prepared Au/Ag BMNPs exhibited excellent catalytic activity and good cycling stability toward 4-nitrophenol (4-NP) reduction according to the synergistic effect between Au and Ag elements. In addition, the catalytic activity was further enhanced under NIR laser irradiation because of their high Surface Plasmon Resonance (SPR) efficiency. The kinetic rate constant (k) and TOF value could reach 0.13 s−1 and 1.33 s−1, respectively, under NIR light (808 nm, 1.0 W/cm2) irradiation at room temperature. We envision that the development of promising routes for high quality of BMNPs could have broad applications in catalysis and environmental governance. [ABSTRACT FROM AUTHOR]