Greenhouse-inspired supra-photothermal CO2 catalysis

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. Light-driven catalytic conversion of CO2 to fuels and chemicals presents a way to reduce reliance on fossil fuels, but new strategies are needed to improve performance. Here the authors find that greenhouse effects can be exploited in photothermal catalysts to enhance their ability to produce methane and carbon monoxide.