Lewis acid-triggered hydroxyl spillover enables selective urea electrooxidation to nitrite with concurrent energy-saving hydrogen production.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41530176.
- Also identified by DOI 10.1038/s41467-026-68302-w and PMC identifier 12902054.
- Licence recorded as CC BY-NC-ND.
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Abstract
Nitrite (NO<sub>2</sub><sup>⁻</sup>) is a high-value chemical pivotal to agriculture and pharmaceuticals, yet its conventional via the Ostwald process is energy-intensive and polluting. Electrochemical urea oxidation reaction (UOR) offers a sustainable NO<sub>2</sub><sup>⁻</sup> synthesis pathway with concurrent energy-saving hydrogen (H<sub>2</sub>) production, but suffers from non-selective N<sub>2</sub>/CO<sub>2</sub> pathways. Here, we report Cr<sup>3+</sup> Lewis acid sites in Ni<sub>3</sub>S<sub>2</sub> that act as hydroxyl (OH<sup>⁻</sup>) pumps, dynamically spilling OH<sup>⁻</sup> to adjacent Ni sites via a Lewis acid-base interaction. This triggers a urea-to-NO<sub>2</sub><sup>⁻</sup> pathway, achieving a NO<sub>2</sub><sup>⁻</sup> yield of 120.98 mg h<sup>-1</sup> cm<sup>-2</sup> (600 mA cm<sup>-2</sup>). The OH<sup>⁻</sup> spillover accelerates C-N cleavage while suppressing N-N coupling, enabling energy-saving H<sub>2</sub> production (3.7 kWh m<sup>-3</sup> at 500 mA cm<sup>-2</sup>) and Zn-urea-air batteries (charging potential 288 mV lower than Zn-air). Techno-economic analysis reveals $1,210.5 per ton of urea processed at 400 mA cm<sup>-2</sup>. This work establishes OH<sup>⁻</sup> spillover as a universal design principle for selective electrocatalysis.