Boosting CH4 selectivity in CO2 electroreduction using a metallacycle-based porous crystal with biomimetic adaptive cavities. Issue 22 (17th February 2022)

• Record Type: Journal Article
• Authors: Wang, Xin; Li, Zhi-Wei; Huang, Zi-Jun; Li, Li-Ping; Peng, Xiao-Ru; Shang, Mei-Jie; Liao, Pei-Sen; Chao, Hsiu-Yi; Ouyang, Gangfeng; Liu, Gao-Feng
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 22(2022)
• Page Start: 11948
• Page End: 11954
• Publication Date: 2022-02-17
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1ta08889k
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : A metallacycle-based porous crystal with intrinsic cavities could efficiently steer CO2 -to-CH4 electrocatalytic conversion by the synergic effect of size-adaptivity and confined microenvironment. Abstract : There is a growing interest in designing electrocatalysts for highly selective electroreduction of CO2 to deeply reduced products such as CH4 . However, CO2 -to-CH4 conversion remains a great challenge in controlling the multi-electron/proton transfer and the adsorption of key intermediates. In this work, a metallacycle-based porous crystal (1 ) was synthesized for selective CO2 -to-CH4 electroconversion in aqueous solution. The single-crystal analysis results disclosed that the metallacycle module of 1 features open metal sites and could be self-adaptive to encapsulate guest molecules of different sizes in its cavity. These enable the metallacycle to function as a nano-reactor to mimic the enzymatic cavity that is surrounded by catalytically active sites and adaptively bind to diverse substrates and intermediates. Accordingly, 1 exhibits desirable CO2 capture capacity, and its porous framework further promotes CO2 diffusion to catalytic sites. The above merits bring about an excellent CH4 selectivity of 70% with a partial current density of 10.3 mA cm −2 in a H-type cell at −1.5 V ( versus the reversible hydrogen electrode), while a CH4 selectivity up to 81% with a partial current density of 23 mA cm −2 in a flow cell. Mechanistic investigations suggested that the adaptive cavity and the synergistic effect of aromatic hydrogen atoms, via hydrogen-bonding interactions, are beneficial to stabilize the key intermediates of CO2 -to-CH4 conversion. This work develops a novel platform to regulate the reactivity and selectivity of CO2 electroreduction reactions.