Ag-Ni(OH)<sub>2</sub>/Cu Heterostructure for Tandem Electrocatalytic Nitrate Reduction to Ammonia Coupled with 5-Hydroxymethylfurfural Electrooxidation.

Chen, Xue; He, Yuexuan; Ding, Guopeng; Feng, Zixuan; Wei, Qianling; Sui, Chunyu; Wang, Zhili; Jiang, Qing · Nano Lett · 2025

basic_science · Level V

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Abstract

Electrochemical reduction of nitrate ions to NH<sub>3</sub> provides a sustainable route for both NH<sub>3</sub> synthesis and wastewater treatment, but it remains challenging. Here we report a Ag-Ni(OH)<sub>2</sub>/Cu NW heterostructure that exhibits a high NH<sub>3</sub> Faraday efficiency of 97.3% with an NH<sub>3</sub> yield rate of 4.01 mg h<sup>-1</sup> cm<sup>-2</sup> at -0.1 V vs RHE. Theoretical studies reveal that the excellent performance of Ag-Ni(OH)<sub>2</sub>/Cu NW results from the multisite synergy via a cascade electrocatalysis, in which Ag and Ni(OH)<sub>2</sub> species promote NO<sub>3</sub><sup>-</sup> reduction to NO<sub>2</sub><sup>-</sup> and H<sub>2</sub>O dissociation to generate *H, respectively, and Ni(OH)<sub>2</sub>/Cu interface accelerates NO<sub>2</sub><sup>-</sup> reduction to NH<sub>3</sub>. Meanwhile, using Ag-Ni(OH)<sub>2</sub>/Cu NW as both the anode and cathode, a two-electrode system integrating the nitrate reduction reaction with the 5-hydroxymethylfurfural oxidation reaction achieves 98.1% NH<sub>3</sub> Faraday efficiency with a 3.17 mg h<sup>-1</sup> cm<sup>-2</sup> NH<sub>3</sub> yield rate and 99.7% 2,5-furandicarboxylic acid selectivity with 99.2% 5-hydroxymethylfurfural conversion.