Abstract: Converting carbon dioxide photocatalytically into fuels using solar energy is an attractive route to move away from a reliance on fossil fuels. Photothermal CO2 catalysis is one approach to achieve this, but improved materials that can more efficiently harvest and use solar energy are needed. Here, we report a supra-photothermal catalyst architecture—inspired by the greenhouse effect—that boosts the performance of a catalyst for CO2 hydrogenation compared to traditional photothermal catalyst designs. The catalyst consists of a nanoporous-silica-encapsulated nickel nanocrystal (Ni@p-SiO2), which is active for methanation and reverse water–gas shift reactions. Under illumination, the local temperatures achieved by Ni@p-SiO2 exceed those of Ni-based catalysts without the SiO2 shell. We suggest that the heat insulation and infrared shielding effects of the SiO2 sheath confine the photothermal energy of the nickel core, enabling a supra-photothermal effect. Catalyst sintering and coking is also lessened in Ni@p-SiO2, which may be due to spatial confinement effects.
