Proton Concentration Tunes the Double-Layer Characteristics of Lead Catalysts to Boost the Electrosynthesis of Glyoxylic Acid.

Xu, Zifan; Lu, Huan; Sheng, Li; Zhang, Long; Qian, Jun; Yu, Jun; Zheng, Jian; Fan, Ming-Hui et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Glyoxylic acid (C<sub>2</sub>H<sub>2</sub>O<sub>3</sub>) is an important platform molecule. Oxalic acid (H<sub>2</sub>C<sub>2</sub>O<sub>4</sub>) electroreduction into C<sub>2</sub>H<sub>2</sub>O<sub>3</sub> offers a sustainable alternative to conventional multistep synthesis while limited by insufficient activity (>-200 mA cm<sup>-2</sup>). Herein, we presented a convenient strategy that created a counterintuitive interfacial structure to decouple the proton supply from surface proton activation on the Pb catalyst via tuning the acidity of the electrolyte. During H<sub>2</sub>C<sub>2</sub>O<sub>4</sub> electroreduction, the activity for C<sub>2</sub>H<sub>2</sub>O<sub>3</sub> reached -420.1 mA cm<sup>-2</sup> in the mixed solution containing saturated H<sub>2</sub>C<sub>2</sub>O<sub>4</sub> and 1.0 M HCl, 2.8 times higher than that (-111.5 mA cm<sup>-2</sup>) in the saturated H<sub>2</sub>C<sub>2</sub>O<sub>4</sub> solution. Based on mechanistic investigation, the adsorption of protons was suppressed, whereas the rate-determining protonation of the adsorbed H<sub>2</sub>C<sub>2</sub>O<sub>4</sub> was facilitated under high acidity conditions. By adopting urea and C<sub>2</sub>H<sub>2</sub>O<sub>3</sub> solution with residual acid as reactants, we further validated commercial feasibility for the downstream separation and transformation of C<sub>2</sub>H<sub>2</sub>O<sub>3</sub> into high-value-added allantoin products.