CO2 adsorption and dissociation on single and double iron atomic molybdenum disulfide catalysts: A DFT study

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Efficient two-dimensional molybdenum disulfide (MoS2) catalysts have not been developed for CO2 reduction. CO2 direct dissociation is the first step and rate determining step for CO2 decomposition reaction. The single and double Fe atomic MoS2 catalysts as well as pristine MoS2 and single S vacancy MoS2 were investigated to explore both adsorption and direct dissociation of CO2. It was found that a sulfur vacancy as well as Fe deposition and doping promoted the adsorption and direct dissociation of CO2 on MoS2. Double Fe atomic MoS2 catalysts had lower energy barrier for CO2 direct dissociation than single Fe atomic MoS2 catalysts. The case with two Fe atoms doped on the same Mo atom of MoS2 had the largest binding energy, highest adsorption energy, and lowest energy barrier among the six types of catalysts investigated. This system also had the highest Bader charge transfer, largest density of states change, and the most obvious electron density differences when adsorbing CO2. A linear relationship was found between the energy barrier and adsorption energy. Fe···O and Fe···C-O bonds were formed for the transition states of CO2 direct dissociation by the two Fe doped on the same Mo atom of MoS2 catalyst whereas only a Fe···O bond was formed for other Fe modified MoS2 catalysts.