The in situ structural evolution of Bi2O3 facilitates the electrocatalytic hydrogenation of oxalic acid to glycolic acid†

Abstract

Electrocatalytic hydrogenation (ECH) of oxalic acid (OX) as feedstock to generate glycolic acid (GA) with high added value has been considered to provide a feasible route for eco-friendly synthesis of GA. Herein, a Bi₂O₃-based electrocatalyst was reported for the first time in the selective ECH of OX to GA in acidic media. At −0.5 V vs. RHE, the selectivity toward GA reached 87% with an OX conversion of 82% in 0.05 M H₂SO₄. Notably, the Bi₂O₃ catalyst underwent a potential-driven reconstruction, resulting in a transformation from Bi₂O₃ particles into a dendrite-like Bi/Bi₂O₃ heterostructure. Kinetic studies demonstrated that the ECH of OX over the reconstituted Bi/Bi₂O₃ occurred through the Eley–Rideal (E–R) mechanism. The superior electrocatalytic efficiency originated from the Bi/Bi₂O₃ heterostructure with abundant defects that optimized the surface charge distribution and boosted the adsorption of the intermediate HOOCCO*, thereby exhibiting a notable selectivity for GA.