Discrete silver nanoparticle infusion across silica aerogels towards versatile catalytic coatings for 4-nitrophenol reduction

Hybrid metallic materials generated from the distributions of discrete nanoparticles offer a superior surface to volume ratio as well as enhanced optical, photonic, and electronic properties compared to bulk metallic materials. Such behaviours are correlated to the nano-scale metal inter-grain domains favouring the presence of electronic vacancies. In this work, an infusion strategy was used to incorporate silver nano-particles across a silica aerogel matrix. Furthermore, the enhancement in catalytic potential was correlated to the macro-properties of the hybrid catalytic monoliths, including their specific surface area and relative pore volume. Interestingly the performance of the samples was found to be optimum for very low loadings of silver nanoparticle dispersion capacity on the order of 0.006 vol%, while very high loadings likely generated extremely strong aggregations leading to more surface silver being available. The incorporation of the minute amounts of discrete nanoparticle distributions within the silica matrix increased the catalytic ability of the materials to degrade 4-nitrophenol by up to 20 times compared to bulk silver nanoparticles. This strategy opens new avenues for the design of complex architectures of either single or multi-metal materials encapsulated within silica for environmental remediation applications.