In recent years, the introduction of light radiation into traditional thermocatalytic systems can significantly improve the efficiency of CO2 conversion into high value-added products under mild conditions, which is helpful to solve the problems of environmental pollution and fossil energy consumption. Therefore, it is imperative to develop efficient catalysts for photothermal CO2 conversion. Among them, supported plasmonic metal nanoparticle-based catalysts show good application prospects: under light irradiation, local surface plasmon resonance (LSPR)-induced thermal electrons on metal nanoparticles are directly injected into the antibond orbital of the adsorbed molecule, which promotes the activation of adsorbed species and reduces the energy barrier in key reaction steps. In addition, the attenuation of the electromagnetic field around the metal support interface caused by the LSPR effect will effectively increase the local temperature of the catalyst and thus promote the reaction kinetics. However, inert carriers have a relatively wide bandgap, which limits light utilization, resulting in low CO2 conversion efficiency. Therefore, there is an urgent need to prepare high-performance photothermal catalysts to meet the needs of practical industrial applications.
Recently,Wang Fenglong, Shandong UniversityThe research group has developed a highly efficient catalyst in which RU nanoparticles are loaded on MnCO2O4 for photothermal CO2 methanation under mild conditions. Experimental characterization and density functional theory (DFT) calculations show that the excellent catalytic activity of RU MnCO2O4 composites under light is due to the dual role of MnCO2O4 supports: on the one hand, photothermal MnCO2O4 nanosheets can significantly increase the local temperature at the interface of metal supports and accelerate the reaction kineticsOn the other hand, the construction of the RU MnCO2O4 interface Schottky heterojunction promotes the rapid migration of photogenerated electrons from MNC2O4 to RU nanoparticles, improves the charge separation efficiency, and thus promotes the adsorption and activation of reactant molecules.
At the same time, the researchers also proposed a reasonable reaction path for the photothermal catalytic CO2 methanation process: first, the CO2 molecule forms HCO3* on the surface of the catalyst by interacting with the hydroxyl species, and at the same time, the H2 molecule dissociates into the atomic H species on the RU nanoparticlesThe resulting H* migrates to the support by extravasation and reacts with HCO3* to form HCOO*, which subsequently decomposes into Co* and H2O;In subsequent steps, due to the strong interaction between the RU MnCO2O4 interface and the CO* intermediate, the heterogeneous interface acts as the active center to facilitate the further generation of CH4 by CO* hydrogenation instead of desorption products, resulting in the formation of gas-phase CO.
In addition, light irradiation promotes CO2 activation, intermediates and CO* conversion, resulting in accelerated CH4 production. Therefore, the CH4 yield of the Ru MnCO2O4-2 catalyst is as high as 663 mmol gcat-1 h-1(5.1 mol gru-1 h-1), which is 12 times, which is better than most reported plasma metal-based catalysts. In addition, under the same energy input conditions, the RU MnCO2O4-2 catalyst exhibits better photothermal CO2 methanation activity than RU TiO2 and RU Al2O3 with the catalyst phase.
reinforcing the efficiency of photothermal catalytic co2 methanation through integration of ru nanoparticles with photothermal mnco2o4 nanosheets. acs nano, 2023. doi: 10.1021/acsnano.3c07630