Investigation of the structure-activity relationship of Cu2O catalysts for CO2 electrochemical reduction

• Megan Maurer, Chemistry, University of Delaware

• Rachel Davidson, Chemistry, University of Delaware

Each year, approximately half of the billions of tons of CO₂ released into the atmosphere from fossil fuel utilization pollutes our atmosphere, contributing to global warming. One method of recycling this CO₂ is CO₂ electrochemical reduction (CO₂ER). However, this technique often requires high overpotentials, which necessitates the use of electrocatalysts. Cu-based catalysts stand out for their ability to produce many desirable CO₂ER products efficiently, but their structure-property relationship remains poorly understood, which is the problem that this research project aims to address.

Three copper(I) oxide morphologies (cube, polygon, and flower) were electrochemically deposited on glassy carbon electrodes. These samples were characterized via scanning electron microscopy (SEM) and Raman spectroscopy before undergoing CO₂ER with varying overpotentials. The gaseous and liquid products were detected and quantified using gas chromatography and proton nuclear magnetic resonance, respectively. In general, a larger percentage of CH₄ was produced with increasing overpotential. Conversely, less CO was produced with increasing overpotential, and the production of H₂ from the competing hydrogen evolution reaction (HER) also decreased. The composition and percentage of the liquid products varied by morphology, but HCOOK was consistently a major liquid product. In addition, the polygon was found to be more selective toward the parasitic HER, whereas the flower produced the widest range of CO₂ER products. Post-catalysis SEM imaging showed that all catalysts degraded similarly, becoming rougher and forming nano-sized fragments around the original crystals.