Promoting Electrocatalytic Glycerol C─C Bond Cleavage to Formate Coupled with H₂ Production Over a Cu_xNi_2–xP Catalyst

Abstract

Electrocatalytic oxidation of glycerol, an oversupplied byproduct of the biodiesel industry, into high‐valued chemicals is alluring to diminishing current dependence on fossil energy. Formic acid is an important glycerol oxidation product that serves as a high‐energy‐density fuel and crucial precursor for the fine chemical industry while developing an electrocatalyst to efficiently convert glycerol into formic acid remains a challenge. Herein, a Cu‐doped nickel phosphide (CuxNi2–xP) electrocatalyst, achieving formate productivity of ≈11 mol m−2 h−1 at 1.54 V versus RHE over a broad glycerol concentration range (10–100 mm) is reported, which is greater than threefolds than that of Ni2P. Furthermore, CuxNi2–xP can enhance the cleavage of C─C bond in glycerol, reducing the production of intermediates and thus attaining high selectivity of formate. In situ experiments integrated with density functional theory (DFT) calculation revealed that the doping of Cu can promote the generation of NiIII─OOH species and enrich glycerol substrates in local environments on CuxNi2–xP surface, thus facilitating reaction efficiency. Finally, the study designed a membrane‐free flow electrolyzer for continuous upgrading glycerol to formate, attaining 16.4 mmol of formate coupled with 0.68 L of H2 at 1.75 V in 8 h.