(Digital Presentation)Cu Coordination Environment Modification Via Atomic Layer Infiltration As High Selective CO2RR Catalyst

Abstract

Carbon dioxide (CO2) is the most notorious greenhouse gas, released by both natural and artificial processes. In an ideal scenario, the production and consumption of CO2 should be balanced so that the concentration of CO2 in atmosphere remains constant to maintain environmental stability. Unfortunately, with the intensification of human industrial activities, this balance has gradually been disrupted, leading to more CO2 production and making global warming a pressing issue. With carbon neutrality gaining increasing attention, electrochemical CO2 reduction reaction (CO2RR) has emerged as a research orientation which converts CO2 to value-added products while storing renewable energy. Cu-based electrocatalysts have been studied extensively for the CO2RR into hydrocarbons in aqueous solutions under environmental conditions. However, they frequently endure low Faradaic Efficiency (FE) and selectivity of specific single product. Particularly, precise construction of Cu micro-environment is of great challenge for the design and fabrication of excellent Cu-based CO2RR catalysts. Atomic layer infiltration (ALI) allows gas phase precursors to penetrate and diffuse into porous substrates through their nanoporous structures and to grow within the subsurface. Aiming at systematically regulating the Cu metal site micro-environment, porous HKUST-1 containing paddle-wheel Cu coordination nodes was chosen as a template and modified with ALI technique in this work. Various metals were introduced into HKUST-1 using ALI method to construct bimetallic sites which tended to produce CO, HCOOH and other products with high FEs. Density Functional Theory (DFT) calculations prove the modification with metals by ALI enhances the adsorption enthalpy of CO2 and alters the bonding interaction between reaction intermediates and adsorption center, thereby changing the reaction pathways. MOF conversion technique based on atomic layer deposition (ALD) will be utilized to fabricate HKUST-1 thin film in our future work, which allows nanometer precision of catalyst loading to balance active-site density with mass/charge transfer. The proposed ALI and ALD techniques elucidate the reliance of CO2RR selectivity on the Cu micro-environment and provide a platform for regulating Cu or other metal-base electrocatalyst coordination environment to facilitate high selectivity of CO2RR in the future