Potential‑Driven Tetragonal CuFe2O4 Phase Transition Enables Near‑Complete Nitrate‑to‑Ammonia Conversion with Minimal Nitrite Accumulation
Year: 2026
Type: preprint
Abstract: The development of electrocatalyst for nearly complete electrocatalytic nitrate reduction without accumulating nitrites in the product feed is indispensable for sustainable nitrate contaminated wastewater treatment and carbon-neutral green ammonia production. In this study, CuFe 2 O 4 nanowires could mimic the bifunctional nature of nitrite reductase where Cu act as nitrate adsorption and deoxygenation center while Fe promoted adsorption of H* and the reduction of *NO to NH 2 . We demonstrate the involvement of a hydride‑transfer pathway supported by obtaining four‑electron transfer from rotating‑disk voltammetry and further corroborated by the mechanistic insights obtained from DFT analysis. The faradaic efficiency for ammonia exceeded 95% at all applied potentials, with an ammonia‑to‑nitrite yield‑rate ratio of 13 at −1.1 V vs. Reversible Hydrogen Electrode. The enhanced nitrite reduction was due to the potential dependent cubic to tetragonal phase transition at higher overpotential exposing undercoordinated iron sites promoting H* adsorption and hydrogenation of *NO. The tandem electrocatalysis mechanism led simultaneously to high NH 3 selectivity, suppressing hydrogen evolution reaction and resulting negligible nitrite accumulation. This work establishes a correlation between ammonia selectivity, surface structure and phase of spinel CuFe 2 O 4 and provides crucial mechanistic insights into reaction pathways of NO 3 - /NO 2 - electroreduction
Source: ChemRxiv
Language: English
Subfield: Catalysis
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7167482007