Activating Mn Sites on MnO2 Hollow Spheres for CO2 Photoreduction

Abstract

Photocatalytic conversion of carbon dioxide (CO₂) to carbon-based fuels is a promising approach to alleviating environmental and energy problems. Therefore, designing photocatalysts with morphological structures that favor gas–solid reactions and exhibit exceptional catalytic efficiencies is strongly demanded. In this work, a porous-framed heterostructure, constructed by anchoring Cs₄PbBr₆ perovskite nanocrystals on MnO₂ hollow spheres, exhibits a 1.8-fold enhancement in the total electron consumption rate (95.3 μmol g^–1 h^–1) for CO₂ photoreduction compared to the original Cs₄PbBr₆ nanocrystals. Detailed optoelectronic characterizations and theoretical calculations demonstrate that the electronic interactions in the heterointerface trigger disproportionation of Mn and help to expose active Mn sites that attract electrons, thus improving the CO₂ activation and the following hydrogenation step to produce COOH*. The open and through porous structure also contributes to the enhanced reaction rate by accelerating mass transfer during the photoreduction reaction. This study provides valuable insights for the development of efficient catalysts for CO₂ photoreduction in gas–solid reactions.