Tuning selectivity and activity of the electrochemical glycerol oxidation reaction by manipulating morphology and exposed facet of spinel cobalt oxides

To further explore the electrooxidation mechanism of biomass-based compounds, it is highly desirable to regulate the proportion of reactive facets , identify facet-governing reactivity through crystal facet engineering. In this study, octahedral and cubic cobalt spinel oxide (Co3O4), each exclusively exposed by one specific type of facet, are selected as two representative microstructure models for tuning the selectivity and productivity of electrochemical glycerol oxidation reaction. The results indicate that the {111}-dominant octahedral Co3O4 plane with a higher population of Co2+ sites exhibits superior electro-catalytic activity for glycerol oxidation compared with the {001}-dominant cubic Co3O4, allowing nearly 65% of glycerol to be converted into a high-value-added dihydroxyacetone (DHA) compound. The average DHA production rate over octahedral Co3O4 (2.5 lmol cm-2h-1) are approximately 3.5 times greater than that over cubic Co3O4 (0.7 lmol cm-2h-1). Electrochemical studies and surface atomic configuration anal-ysis reveal that {111}-dominant octahedral Co3O4 with a higher density of active cobalt ion yields unique reactant adsorption and charge transfer, leading to increased glycerol oxidation reactivity and productiv-ity. The present study emphasizes the significance of controlling the highly active facet in developing effi-cient and selective electrocatalysts.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

In order to explore the electrooxidation mechanism of biomass-based compounds, it is important to control the proportion of reactive facets and identify the facet-governing reactivity through crystal facet engineering. Octahedral and cubic cobalt spinel oxide (Co3O4) microstructures are used as models to tune the selectivity and productivity of the electrochemical glycerol oxidation reaction. The results show that the {111}-dominant octahedral Co3O4 plane exhibits superior electro-catalytic activity compared to the {001}-dominant cubic Co3O4, resulting in a higher conversion of glycerol into dihydroxyacetone (DHA) compounds. The present study highlights the significance of controlling the highly active facet in the development of efficient and selective electrocatalysts.