Ag-Pd bimetallic hollow nanostructures with tunable compositions and structures for the reduction of 4-nitrophenol

Abstract

Bimetallic hollow nanostructures are of interest for high-performance nanocatalysis and achieving a higher utilization efficiency of noble metals. This paper reports the synthesis of Ag-Pd bimetallic hollow nano-hexagon with outer sizes of about 27 nm and wall thicknesses of 3–5 nm by galvanic replacement reaction (GRR) coupled with a co-reduction method using Ag nanospheres as sacrificial templates. Cetyltrimethylammonium bromide (CTAB) exhibited a double effect on controlling morphologies. First, it acted as the capping agent to mediate the rate of dissolution and deposition on different planes by selectively absorption, and second, it provided Br- ion with ability to promote the GRR. The compositions and structures of Ag-Pd bimetals could be finely tuned by changing the amount of palladium chloride acid (H2PdCl4) while maintaining the volume of Ag seed templates unaltered. By comparing the TOF rate of 4-nitrophenol reduction reaction over different samples of Ag-Pd bimetals as the catalyst, we conclude that hollow bimetallic nano-hexagons with the composition of AgPd0.61 exhibited the highest catalytic activity due to the high surface areas, synergy effect between the two metals, and {100} exposure facets.