Understanding the water molecule effect in metal-free B-based electrocatalysts for electrochemical CO reduction

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2022-03, Vol.1 (12), p.658-6522
• Main Authors: Meng, Yuxiao, Xu, Zhangmeng, Shen, Zhangfeng, Xia, Qineng, Cao, Yongyong, Wang, Yangang, Li, Xi
• Format: Article
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d1ta10127g

Electrocatalytic CO 2 reduction (CO 2 RR) is a feasible and economical way to eliminate CO 2 via converting it into useful products. However, this process is hampered by the lack of highly active and stable catalysts. Against this backdrop, single and double boron atom-doped bismuthene catalysts (B@Bi and B 2 @Bi) for the CO 2 RR were designed. The nature of the CO 2 activation and reduction mechanisms on B@Bi and B 2 @Bi was explored using density functional theory (DFT) and ab initio molecular dynamics simulations (AIMD). The results indicate that the most feasible product is CH 4 on B@Bi, while the C 2 H 4 product is both thermodynamically and kinetically favored on B 2 @Bi. Moreover, water molecules were also introduced to explore their effects on the CO 2 RR performance. In an environment with 30H 2 O molecules, hydrogen bonding interactions between the water molecules and the intermediate reduce the η values of CH 4 (0.25 V) on B@Bi and C 2 H 4 (0.90 V) on B 2 @Bi compared to those in the gas phase. The thermodynamic potential-determining step (PDS) for CH 4 synthesis changes from *OCH in the gas phase to *OCH 2 formation on B@Bi due to the number of hydrogen bonds and intermediates with different polarity. C-C coupling is still the PDS for C 2 H 4 generation on B 2 @Bi. The calculation of the hydrogen evolution reaction (HER) as a reaction competitive with the CO 2 RR shows that B@Bi and B@Bi offer excellent selectivity in the water environment. This work provides useful insights into the development of highly efficient metal-free CO 2 RR electrocatalysts and highlights the critical role of hydrogen bonding with water molecules in CO 2 RR. Electrocatalytic CO 2 reduction (CO 2 RR) is a feasible and economical way to eliminate CO 2 via converting it into useful products.