What to do with the excess renewable energy created during off peak hours and how to close the carbon cycle are two of the most relevant research questions to be answered at the moment. The electrochemical CO2 reduction reaction (CO2RR) is a promising solution to both of these problems. Electrochemical CO2RR allows us to convert CO2 taken directly from the atmosphere or from flue gasses and electrochemical reduce it, thus helping remove CO2 from the atmosphere and providing a form of energy storage for renewables. However, conventional methods of synthesizing CO2RR catalysts can produce harmful wastes. Herein, a sustainable catalyst synthesis method is developed which by using cheap and abundant cornstarch as the feedstock, and doping it with nickel (Ni) from a simulated metal-containing wastewater, before finally doping it with nitrogen (N) containing urea to create a highly efficient metal-nitrogen-carbon (M-N-C) catalyst which is dominated by single atomic Ni sites without the need for a waste producing acid wash post-treatment. This cornstarch-based catalyst resulted in CO production with a Faradaic efficiency (FE) of 92% and a CO partial current density of 11.6 mA/cm2 at −0.8 V versus RHE. Under the same testing conditions and with the same Ni content, a catalyst prepared via wet impregnation achieved only a CO current density of 9.3 mA/cm2, while when cornstarch was replaced with more expensive graphene oxide a CO current density of 11.5 mA/cm2 was achieved, but with a lower FE (CO) at 81%. Findings from this work provide insights into using low-cost sustainable biomaterials and non-waste producing methods to produce effective electrochemical CO2RR catalysts.

Sustainable synthesis of nickel-nitrogen-carbon catalysts using cornstarch and wastewater for efficient electrochemical reduction of CO2 to CO

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.