Synthesis of tailored Au@TiO2 core–shell nanoparticles for photocatalytic reforming of ethanol

• We have developed a technique for coating TiO2 shells on Au nanoparticles.
• We can tune the shell thickness over a wide range with minimal coating steps.
• Catalytic properties were studied under UV irradiation.
• Catalytic activity is optimal at a weight percent of 0.731%.
• Catalytic activity is optimal when the sample is processed at 600 °C.

A controlled sol–gel process has been developed to coat gold nanoparticles with a thin layer of titanium dioxide to produce Au@TiO2 core–shell catalyst particles, which can be rendered crystalline via calcination at high temperatures. The Au weight percent can be controlled by repeating the coating process while decreasing the water content and core concentration, making it possible to systematically tune the shell thickness over a large range without the need for an excessive number of coating steps. The encapsulating TiO2 shells protect the Au cores from sintering during processing, which makes it possible to investigate the effect of varying the processing conditions for the catalyst without altering the Au particle size. Catalysts with varying Au weight percents and corresponding shell thicknesses, as well as various calcination temperatures, were tested for their efficacy in the UV-driven reforming of ethanol to produce hydrogen. It was found that an Au weight percent of 0.731% was optimal, along with a calcination temperature of 600 °C, as these conditions produced a sufficiently low Au loading percent while still enabling diffusion of the solution to the core.

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