The production of urea, an essential but pervasive fertilizer, releases 11.5 million tons of CO₂  annually in the U.S. alone, representing a significant source of emissions that hinders progress towards a carbon-neutral society. To lower the carbon footprint of urea production, this CNAP-funded research team tested a new electrochemical process using renewable electricity at lower temperatures and pressures.

Project Summary

This team tested different materials for their ability to electrochemically reduce carbon dioxide and nitrate to produce urea. Through a newly built reactor specifically designed for this reduction process and computer simulations, they were able to better understand the microscopic steps involved in this process as well as identify new improvement areas for its effectiveness and reproducibility. 
The team replaced stable nitrogen with reactive nitrate, resulting in a reduction of the overall energy required for urea production, which also increased its efficiency and scalability. Given that nitrate is one of the most common water pollutants, coupling it with carbon dioxide offers the dual benefit of producing nutrient-dense urea in a carbon-neutral fashion while simultaneously remediating an abundant pollutant.
The project findings have been shared with the broader scientific community to contribute to ongoing CO₂ conversion efforts. The project team secured nearly $4,000,000 in additional funding from the National Science Foundation (NSF) and Keck Foundation to continue investigating additional electrocatalysts for the coupling of CO₂ and nitrate to increase the efficiency of urea production, potentially establishing industrial partnerships to achieve greater scalability.  

Key wins
The project team developed innovative approaches using copper as an electrocatalyst. They made progress on characterizing and testing copper-based electrocatalysts for nitrate reduction and CO₂ coupling, and included how specific parameters could be changed to achieve higher efficiency. The team also advanced existing research on how ammonia is formed through different tests, revealing important information about the interaction between nitrate and CO₂ during the process. 

This team received a $50,000 CNAP faculty research grant in 2022. 

Project team: Nirala Singh, PI (Chemical Engineering | U-M Ann Arbor); Bryan Goldsmith (Chemical Engineering | U-M Ann Arbor); Dean Sweeney (Chemical Engineering | U-M Ann Arbor);  Roshini Dantuluri (Chemical Engineering | U-M Ann Arbor); Libo Yao (Chemical Engineering | U-M Ann Arbor).

In the Media 

• A leap toward carbon neutrality, CO2 to methanol (Michigan News | May 2024)

Publications

• Identifying the active site of Cu/Cu2O for electrocatalytic nitrate reduction reaction to ammonia (Chem Catalysis | January 2024)

• Role of Structural and Compositional Changes of Cu2O Nanocubes in Nitrate Electroreduction to Ammonia (ACS Applied Energy Materials | October 2024)

• Electrochemical CO2 Reduction to Methanol by Cobalt Phthalocyanine: Quantifying CO2 and CO Binding Strengths and Their Influence on Methanol Production (ACS Catalysis | December 2023)

• Challenges and opportunities in translating immobilized molecular catalysts for electrochemical CO2 reduction from aqueous-phase batch cells to gas-fed flow electrolyzers (Current Opinion in Electrochemistry | October 2023)