Cu2+-induced surface structure transformation on Au nanocubes from a concave to a convex configuration: mechanism and catalytic performance

Abstract

Investigation into the relationship between the surface structure and the catalytic performance of nanocatalysts is pivotal for guiding the preparation of high performance nanocatalyst. However, there is lack of effective strategy for fine tuning of surface structure. In this paper, eight kinds of Au nanocubes (AuNCs) were synthesized from concave, flat, to convex structures with the use of trace Cu2+, and surface structure-dependent catalytic performance was investigated. In the synthesis, H2O2 reduce Au3+ to Au+ in alkaline CTAB solution firstly, and then ascorbic acid are added to initialize the growth of AuNC (15 min). Increasing Cu2+ led to an evolution of concave→flat→convex surfaces, corresponding to an evolution of {hk0} facets. The mechanism is that Cu2+ ion can fast catalyze the reaction between H2O2 and ascorbic acid to produce hydroxyl radicals, which promotes more Au0 deposition on the surface. More importantly, the catalytic performance of AuNCs decreases as the evolution of concave→flat→convex surfaces, and the concave one is much larger than flat and convex ones. It was the first report that simple substances induced the concavo-convex transformation of AuNC, and elucidate the relationship between the surface structure and catalytic performance of AuNCs.