Dynamic Restructuring of Strongly Interacting Copper Single-Atom and Atomic Cluster Sites for Selective Electrosynthesis of Hydroxylamine
Shengbo Zhang, Tongfei Shi, Miaomiao Han, Qiong Lei, Yong Jiang, Xinyuan Zhang, Huajie Yin, Haimin Zhang, Huijun Zhao
Abstract
The ambient electrosynthesis of high-value hydroxylamine (NH 2 OH) using nitrogenous precursors has garnered significant research attention. However, uncovering the real electrocatalytic sites for the selective synthesis of NH 2 OH under operando electrocatalysis remains challenging. Herein, we report an oxygen-coordinated copper (Cu) single atoms and atomic clusters coanchored on a carbonized bacterial cellulose catalyst (Cu-SAs/ACs-CBC) via Cu–O 4 /Cu 2 coordination for the selective electrocatalytic synthesis of NH 2 OH using nitrate (NO 3 – ) as nitrogen source. The Cu-SAs/ACs-CBC exhibits significantly enhanced electrocatalytic activity toward NH 2 OH synthesis, achieving a yield rate of 273.6 ± 20.6 μmol h –1 cm –2 and a corresponding faradaic efficiency (FE) of 57.8 ± 4.4% at −0.8 V (vs RHE), whereas Cu single atoms alone are inclined to generate ammonia. Furthermore, we propose a one-step electrochemical strategy for synthesizing cyclohexanone oxime (CO) from NO 3 – and cyclohexanone using Cu-SAs/ACs-CBC, achieving a CO yield rate of 525.0 ± 45.3 μmol h –1 cm –2 with an FE of 80.5 ± 6.9% at −1.0 V (vs RHE) in a flow cell. The in situ X-ray absorption spectra reveal that Cu–O 4 /Cu 2 in Cu-SAs/ACs-CBC is electrochemically reconstituted to form Cu–C 2 O/Cu 8 as the real active site for selective NH 2 OH synthesis. Theoretical calculations further unveil that the electrochemically reconstituted Cu–C 2 O/Cu 8 site, with its synergistic effect, efficiently regulates the adsorption configuration of NO 3 –, therefore greatly improving the selectivity of NH 2 OH during electrocatalysis.