Abstract
The electrocatalytic CO2 reduction reaction (CO2RR) is considered as one of the most promising approaches to synthesizing carbonaceous fuels and chemicals without utilizing fossil resources. However, current technologies are still in the early phase focusing primarily on identifying optimal electrode materials and reaction conditions. Doped graphene-based materials are among the best CO2RR electrocatalysts and in the present work we have performed a computational screening study to identify suitable graphene catalysts for CO2RR to CO under alkaline conditions. Several types of modified-graphene frameworks doped with metallic and non-metallic elements were considered. After establishing thermodynamically stable electrodes, the electrochemical CO2RR to CO is studied in the alkaline media. Both concerted proton-coupled electron transfer (PCET) and decoupled proton and electron transfer (ETPT) mechanisms were considered by developing and using a generalization of the computational hydrogen electrode approach. It is established that the CO2 electrosorption and associated charge transfer along the ETPT pathway are of utmost importance and significantly impact the electrochemical thermodynamics of CO2RR. Our study suggests an exceptional performance of metal-doped nitrogen-coordinated graphene electrodes, especially 3N-coordinated graphene electrodes.
Highlights
The extensive use of fossil resources has escalated the emission of green house gases, CO2, and disrupted the atmospheric carbon balance
Thermodynamic stability against dissolution is a key material property mandatory for maintaining electrocatalytic activity and, we first addressed the stability of our graphene model electrodes against pristine graphene and the thermodynamically most stable phase of the dopant
We found that majority of the studied dimers (M2_SV and MPt_SV) in single vacancies are thermodynamically unstable and these results are presented and discussed solely in the SM
Summary
The extensive use of fossil resources has escalated the emission of green house gases, CO2, and disrupted the atmospheric carbon balance. An appealing approach for maintaining this balance is to utilize renewable energy resources but their intermittent nature presents a serious obstacle in the energy conversion and storage applications (Vasileff et al, 2017; Jia C. et al, 2019). In this regard, converting renewable electrical energy into chemical energy through the electrochemical CO2 reduction reaction (CO2RR) has been identified as an efficient solution (Tian et al, 2018; Jia C. et al, 2019). CO2 is a highly stable molecule as reflected by its high negative reduction potential (−1.90 V vs. SHE)
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