Liquid metal core–shell structures functionalised via mechanical agitation: the example of Field's metal

Exploring the concept of liquid processing and solidification of low melting point alloys can provide new routes for the creation of functional micro and nanoparticles. Here we show that it is possible to produce particles of Field's metal (an alloy of bismuth 32.5 wt%, tin 16.5 wt% and indium 51 wt%) in a one-step mechanical agitation (ultrasonication) procedure. The synthesis takes place just above 62 °C, the melting point of Field's metal, and results in the formation of low-dimensional particles after solidification. It is demonstrated that the sonication process produces nearly spherical core–shell metal–metal oxide heterostructures. Classic alloy-related defects, in the forms of grain boundaries and edge locations, emerge after the solidification. We show that by the incorporation of Ag, either using direct alloying or an Ag salt precursor during the sonication process, this metal appears in the core of the metal–metal oxide heterostructures. Interestingly, the modification of particles with Ag gives specific selectivity for the degradation of two typical azo dyes. The one-step low-temperature synthesis and solidification procedure, presented in this work, can be readily extended for designing catalysts or other functional materials with desired specificity and selectivity.