Atomic-Scale Insights into Carbon Dioxide Hydrogenation over Bimetallic Iron–Cobalt Catalysts: A Density Functional Theory Study

Abstract

The conversion of carbon dioxide to fuels and chemicals is a promising long-term approach for mitigating CO2 emissions. Despite extensive experimental efforts, a fundamental understanding of the bimetallic catalytic structures that selectively produce the desired products is still lacking. Here, we report on a computational surface science approach into the effect of the Fe doping of Co(111) surfaces in relation to CO2 hydrogenation to C1 products. Our results indicate that Fe doping increases the binding strength of surface species but slightly decreases the overall catalytic activity due to an increase in the rate-limiting step of CO dissociation. FeCo(111) surfaces hinder hydrogenation reactions due to lower H coverages and higher activation energies. These effects are linked to the Lewis basic character of the Fe atoms in FeCo(111), leading to an increased charge on the adsorbates. The main effect of Fe doping is identified as the inhibition of oxygen removal from cobalt surfaces, which can be expected to lead to the formation of oxidic phases on bimetallic FeCo catalysts. Overall, our study provides comprehensive mechanistic insights related to the effect of Fe doping on the catalytic behavior and structural evolution of FeCo bimetallic catalysts, which can contribute to the rational design of bimetallic catalysts.

Recent Developments on CO2 Hydrogenation Performance over Structured Zeolites: A Review on Properties, Synthesis, and Characterization

“…Lastly, the top-down approach often leads to the generation of a high number of oxygen functionalities on carbon surfaces, which negatively affect CO2 hydrogenation over structured zeolites due to the formation of oxy-carbides [70]. Tuncer and Kizilkaya [71] revealed that the topdown method of Fe doping on Co(111) surfaces suppresses oxygen eviction from cobalt surfaces, forming oxide phases on bimetallic FeCo catalysts, hence, potentially restricting hydrogenation reactions. Heo and Park [72] presented that the thermal reduction process is capable of removing oxygen functionalities, thus increasing CO2 affinity and uptake on the carbon surfaces.…”