Low-pressure plasma process for the dry synthesis of cactus-like Au-TiO₂ nanocatalysts for toluene degradation

The development of environment-friendly, low-cost and efficient catalyst preparation processes has always been a major issue in the field of catalysis. Wet chemistry methods are often used but these techniques are not sustainable, as post waste solution treatment remains an important drawback. Here an innovative dry low-pressure plasma process for metal nanoparticles supported nanocatalysts preparation is reported. The solid metal and oxide support precursors are physically mixed and then exposed to a radiofrequency Ar/N₂ plasma discharge, leading to the precursor degradation and the subsequent nanoparticles generation, without pre- or post- preparation steps. The metal nanoparticle loading and the particle size of metal and oxide support can be easily tuned by changing the ratio of the precursor materials, making the process simple, versatile, highly efficient, and scalable. As a proof of concept, gold nanoparticles (Au NPs) supported on titanium dioxide (TiO₂) were prepared and tested as nanocatalysts for toluene (C₇H₈) degradation at temperatures ranging from 25 to 450 °C. Up to 100% of C₇H₈ conversion into CO₂ was achieved over the Au-TiO₂ nanocatalysts, demonstrating that this dry method is a very efficient way to prepare highly active nanocatalysts.