Effect of ordered and disordered phases of unsupported Ag3In nanoparticles on the catalytic reduction of p-nitrophenol

• Controlled synthesis of Ag3In nanoparticles in ordered and disordered structures.
• Better catalytic activity observed for ordered Ag3In in the reduction of para-nitrophenol.
• Catalytic activity tuned by the ordered distribution of indium in the active Ag metal matrix.

A detailed study has been done on the combined effect of the reaction time and the effect of surfactants namely, polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide in the formation of ordered (Ag3In) and disordered (Ag0.75In0.25) phases. The catalytic activity of the samples has been checked for the reduction of para-nitrophenol (PNP) to para-aminophenol (PAP) using NaBH4 as the reducing agent. Ag3In obtained at shorter period using PVP as the surfactant showed better catalytic activity with a rate constant of 8.4 × 10−3 s−1 followed by a substantial decrease to 1.83 × 10−3 s−1 for the sample obtained at longer period. The observed trends in the catalytic activity have been explained based on the ordered–disordered structural transition, particle agglomeration and different stoichiometric ratios of Ag to In.

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