Mechanisms of CO2 reduction into CO and formic acid on Fe (100): a DFT study

Abstract

Understanding the mechanism of CO2 reduction on iron is crucial for the design of more efficient and cheaper iron electrocatalyst for CO2 conversion. In the present study, we have employed spin-polarized density functional theory calculations within the generalized gradient approximation (DFT-GGA) to elucidate the mechanism of CO2 reduction into carbon monoxide and formic acid on the Fe (100) facet. We also sort to understand the transformations of the other isomers of adsorbed CO2 on iron as earlier mechanistic studies are centred on the transformations of the C2v geometry alone and not the other possible conformations i.e., flip-C2v and Cs modes. Two alternative reduction routes were considered i.e., the direct CO2 dissociation against the hydrogen-assisted CO2 transformation through formate and carboxylate into CO and formic acid. Our results show that CO2 in the C2v mode is the precursor to the formation of both products i.e., CO and formic acid. Both the formation and transformation of CO2 in the Cs and flip-C2v is challenging kinetically and thermodynamically compared to the C2v mode. The formic acid formation is favoured over CO via the reverse water gas shift reaction mechanism on Fe (100). Both formic acid formation and CO formation will proceed via the carboxylate intermediate since formate is a stable intermediate whose transformation into formic acid is challenging both kinetically and thermodynamically. Graphic abstract

Gallium Nitride‐based Materials as Promising Catalysts for CO2 Reduction: A DFT Study on the Effect of CO2 Coverage and the Incorporation of Mg Doping or Substitutional In

“…Both the fields of homogeneous and heterogeneous catalysis have been extensively explored, [12–19] and several catalysts have been reported experimentally to efficiently convert CO 2 into chemicals and fuels. In this regard, density functional theory (DFT) investigations can lead to an in‐depth understanding of the structure/property relationship, and therefore contribute to the development of highly selective and efficient catalysts [20–23] …”

“…In this regard, density functional theory (DFT) investigations can lead to an indepth understanding of the structure/property relationship, and therefore contribute to the development of highly selective and efficient catalysts. [20][21][22][23] Among the promising catalysts reported in literature, we have addressed our attention to the thermodynamically stable wurtzite gallium nitride (GaN), which has shown unique electronic and optical properties. [24,25] Like other IIIÀ V semiconductor materials, the IIIÀ N family provides two ways to tune the material properties depending on the applications' requirements: the incorporation of donor or acceptors [26][27][28][29][30] and the formation of substitutional alloys using isovalent In or Al.…”