Improvement of carbon dioxide electroreduction by crystal surface modification of ZIF-8

Metal-organic frameworks (MOFs) possess high CO2 adsorption properties and are considered to be a promising candidate for the electrochemical carbon dioxide reduction reaction (eCO2RR). However, their insufficient selectivity and current density constrain their further exploration in the eCO2RR. In this work, by introducing a very small proportion of 2,5-dihydroxyterephthalic acid (DOBDC) into ZIF-8, a surface modified ZIF-8-5% catalyst was synthesized by a post-modification method, exhibiting enhanced selectivity (from 56% to 79%) and current density (from -4 mA cm-2 to -10 mA m-2) compared to ZIF-8. Density functional theory (DFT) calculations further demonstrate that the boosted eCO2RR performance on ZIF-8-5% could be attributed to the improved formation of the *COOH intermediate stemming from successful DOBDC surface modification. This work opens a new path for improving the catalytic properties of MOFs via their surface modification.The authors acknowledge funding from Generalitat de Catalunya 2021 SGR 01581 and 2021 SGR 00457. T. Z., J. R. M. and J. A. acknowledge funding from the projects (PID2020-116093RB-C42 and -C43) funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, by the “European Union”. This study was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa program from Spanish MCIN/AEI (grant no.: CEX2021-001214-S). ICN2 and IREC are funded by the CERCA Programme/Generalitat de Catalunya. A part of the present work has been performed in the framework of Universitat Autònoma de Barcelona Materials Science PhD program. T. Z. has received funding from the CSC-UAB PhD scholarship program (201706180028). X. H. and Y. H. Y. thank China Scholarship Council for scholarship support (201804910551 and 201806650010).With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2021-001214-S)Peer reviewe