Shaping nanoparticle-based aerogels for efficient light-driven catalysis

Aerogels synthesized from preformed metal oxide nanoparticles exhibit high crystallinity and can be manufactured in transparent form, making them appealing for photo- and photothermal catalysis. To date, translucent nanoparticle-based aerogels are primarily produced in monolithic form by casting techniques, which are labor-intensive and costly, and these centimeter-sized bodies are prone to mass transport limitations when applied in catalysis. Here, we present a simple process to prepare millimeter-sized worm-shaped and spherical aerogel granules with high optical clarity and large specific surface areas ranging from 130 to 550 m2 g-1, using colloidally stable dispersions of TiO2, ZrO2, and In2O3 nanocrystals. These granules are easier to produce and handle, and our Pd/TiO2 aerogel granules demonstrate superior photocatalytic performance in methanol decomposition, achieving nearly complete conversion of 1 mol% methanol in air at high flow rates (space velocity of similar to 115 L g-1 h-1). This significant improvement over their monolithic counterparts highlights the potential of aerogel shaping to enhance their viability for practical applications such as the photocatalytic oxidation of volatile organic compounds.