Construction of proton affinity environment around Ni-sites to enhanced electrocatalytic carbon‑carbon coupling

Development of electrocatalytic reduction of carbonyl compounds for carbon‑carbon (C C) coupling represents an effective pathway to achieve sustainable synthesis of multi‑carbon chemicals. The hydrogen evolution reaction (HER) is considered the most significant competitive process, which could be suppressed by weakening the adsorption of protons on interface or by making protons in the electrolyte inactive through the use of certain additives. However, increasing the coverage of protons and carbonyl molecules are necessary to facilitate the generation of hydrogenation intermediates during C C coupling. To reconcile this contradiction, a Ni-based catalyst for electrocatalytic coupling of formaldehyde has been developed, decorated with phosphate groups around Ni sits. The following enhancement could be achieved: 1) Ni sites enhance the adsorption of formaldehyde on catalyst surface and promote their electroreduction; 2) Phosphate groups near the Ni sites can act as protons affinity sites to prevent their self-coupling. As the result, the adsorbed HCHO and hydrogen can be balanced to facile the formation of intermediate *CH 2 OH during C C coupling. Consequently, the PD-Ni/C@CP catalyst exhibits outstanding performance in the continuous preparation of ethylene glycol, with a production rate of 22 mmol/(L·min) and a Faradaic efficiency exceeding 90%, highlighting its potential for the efficient and sustainable synthesis of other high-value chemicals.