Synthesis of Ag–Ag2S Janus nanoparticles supported on an environmentally benign cellulose template and their catalytic applications

Abstract

Synthesis of Ag–Ag₂S Janus nanoparticles (JNP) by a one step co-precipitation technique using a NaOH–thiourea–urea aqueous solution has been reported. The NaOH in cellulose solution acted as the precipitant of Ag–Ag₂S nanoparticles and environmentally benign cellulose was used as a template to promote the growth of nanoparticles. The cellulose was extracted from Bambusa tulda, a locally available bamboo species and was carried out by adopting a green approach using a combination of both chemical and biochemical treatment. The synthesized Ag–Ag₂S JNP was characterized by UV-Visible spectroscopy, powder XRD, TEM, SEM-EDX and XPS analysis. The TEM study reveals that most of the Ag–Ag₂S JNP were spherical in shape and fall in the size range of 10–15 nm. XRD analysis of the Ag–Ag₂S JNP shows diffraction peaks for the (111), (200) and (220) planes of a face centered cubic Ag⁰ crystal along with the characteristic peaks due to Ag₂S, which provide evidence for the coexistence of Ag₂S and Ag on the cellulose support. The method offers a facile and green pathway for the fabrication of Ag–Ag₂S JNP and the synthesized Ag–Ag₂S JNP were employed as a heterogeneous catalyst in a model reaction based on the reduction of p-nitrophenol to p-aminophenol. The metal nanocatalysts could be recycled and reused several times without significant loss of their catalytic activities.