Nano-porous Carbon Cathodes for the Electrocatalytic Reduction of CO2 to Methanol

Abstract

The electrocatalytic reduction of CO2 (CO2ER) has gained a lot of attention in the past few decades as a strategy for Carbon Utilization (CU). CO2ER creates a pathway for transforming CO2 into numerous carbonaceous products, such as CO, COOH, CHO, CH3OH, CH4, and other C2 products like CH3CH2OH and CH3COOH. The most difficult challenges associated with CO2ER are low current densities, competing Hydrogen Evolution Reaction (HER), target product selectivity, and thermodynamic constraints favoring the formation of CO, COOH, and CHO. Therefore, synthesizing catalysts with high selectivity towards other, rather more challenging to obtain, CO2RR products is crucial in converting CO2 into a wider range of useful products. In this study, the potential of using a carbonized MOF-based composite, HKUST-1, grown directly on a copper mesh substrate (H-1@CM-C500) was demonstrated. Features like having a conductive and methanol selective cupric metal center, tunable pore structure, thermal stability, and electrochemically active Cu/Cu2O metal phases are what makes this composite exceptional. The lack of a binder in synthesizing the composite creates an enhanced interface that promotes higher activity, and methanol selectivity. Raman spectrum of H-1@CM-C500 with an ID/IG ratio of 0.56 was observed, with a high dispersion of metallic copper and Cu2O at the surface of the nanoparticles from SEM, TEM, and XPS analyses. H-1@CM-C500 electrodes exhibited a high FEmethanol of around 34.0% at an applied potential of -1.6 V vs. Ag/AgCl (-0.9 V vs. RHE) and a current density of 25.6 mA/cm2 , owing to its exceptional conductivity, metal-carbon synergy, and abundance of active sites. A review of the existing literature regarding CO2ER to methanol is included. A lack of diverse MOF/support composites in literature makes this exploration highly relevant, creating a solid background for further research on CO2ER to methanol, which will eventually diversify and strengthen CU into fuels and may also compliment the methanol industry in diverting their CO2 emissions into product.

Date of Award	25 Dec 2023
Original language	American English
Supervisor	Maryam Khaleel (Supervisor)