Efficient Electrocatalytic Oxidation of Glycerol via Promoted OH* Generation over Single-Atom-Bismuth-Doped Spinel Co3O4

The renewable electricity-driven electrocatalytic oxidation of biomass represents a pathway to produce value-added chemicals from waste biomass such as glycerol (a byproduct of industrial biodiesel production). However, it remains difficult to design an efficient electrocatalyst with explicit structure-property relationships. Herein, we report a single-atom bismuth (Bi)-doping strategy to endow Co3O4 with enhanced activity and selectivity toward electrocatalytic glycerol oxidation reaction (GOR). Experimental characterizations and theoretical calculations reveal that single-atom Bi substitutes cobalt at octahedral sites (CoOh3+) in Co3O4, facilitating the generation of reactive hydroxyl species (OH*) at adjacent tetrahedral Co sites (CoTd2+). Mechanism studies demonstrate that OH* accelerates the oxidation of hydroxyl groups and carbon-carbon (C-C) bond cleavage, achieving GOR activity (400 mA cm-2 at 1.446 V vs reversible hydrogen electrode, RHE) and high faradaic efficiency of formate (97.05 +/- 2.55%). Our study shows a promising way to promote the electro-oxidation activity of spinel oxides for biomass valorization by a single-atom doping strategy.

Automated summary

This study reports a single-atom doping strategy to enhance the activity and selectivity of Co3O4 in the electrocatalytic oxidation reaction of glycerol. Experimental and theoretical investigations reveal that the strategy generates reactive OH* species at CoTd2+ sites by substituting Bi for CoOh3+ sites in Co3O4. Mechanistic studies demonstrate that OH* accelerates the oxidation and cleavage of hydroxy groups and C-C bonds, achieving efficient glycerol oxidation.