Highly selective urea electrooxidation coupled with efficient hydrogen evolution.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39004672.
- Also identified by DOI 10.1038/s41467-024-50343-8 and PMC identifier 11247087.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Electrochemical urea oxidation offers a sustainable avenue for H<sub>2</sub> production and wastewater denitrification within the water-energy nexus; however, its wide application is limited by detrimental cyanate or nitrite production instead of innocuous N<sub>2</sub>. Herein we demonstrate that atomically isolated asymmetric Ni-O-Ti sites on Ti foam anode achieve a N<sub>2</sub> selectivity of 99%, surpassing the connected symmetric Ni-O-Ni counterparts in documented Ni-based electrocatalysts with N<sub>2</sub> selectivity below 55%, and also deliver a H<sub>2</sub> evolution rate of 22.0 mL h<sup>-1</sup> when coupled to a Pt counter cathode under 213 mA cm<sup>-2</sup> at 1.40 V<sub>RHE</sub>. These asymmetric sites, featuring oxygenophilic Ti adjacent to Ni, favor interaction with the carbonyl over amino groups in urea, thus preventing premature resonant C⎓N bond breakage before intramolecular N-N coupling towards N<sub>2</sub> evolution. A prototype device powered by a commercial Si photovoltaic cell is further developed for solar-powered on-site urine processing and decentralized H<sub>2</sub> production.