Monolithic photonic architecture for volumetric illumination in plasmonic photocatalysis

Recent research in high-temperature photocatalysis is rapidly revealing the unique advantages of using light to augment or replace pure thermal energy in chemical synthesis. However, poor penetration of light into a typical powder catalyst creates a major challenge for efficient photo-driven processes. This article presents a novel plasmonic catalyst system with a 3D photonic design that reshapes the balance between thermal, optical, and mass transport. This unique 3D porous architecture allows for the catalyst bed to be illuminated volumetrically while improving mass transport over traditional aerogels. When compared to a powdered catalyst, this monolithic supported plasmonic Rh/SiO₂ catalyst exhibits dramatically increased response to light, both in increased reaction rate and improved selectivity for CO₂ reduction. The insertion of a pelletized sacrificial ZnO tetrapod scaffolding during aerogel synthesis resolves the mass transport problems present in other 3D aerogel-based catalysts. Further, the ZnO scaffolding allows for far easier nanoparticle loading as well as more facile adjustments to the aerogel's surface chemistry compared to a conventional aerogel made using standard methods.