Recent advances in glycerol valorization via electrooxidation: Catalyst, mechanism and device

Glycerol is one of the most important biomass-based platform molecules, massively produced as a by-product in the biodiesel industry. Its high purification cost from the crude glycerol raw material limits its application and demands new strategies for valorization. Compared to the conventional thermocatalytic strategies, the electrocatalytic strategies can not only enable the selective conversion at mild conditions but also pair up the cathodic reactions for the co-production with higher efficiencies. In this review, we summarize the recent advances of catalyst designs and mechanistic understandings for the electrocatalytic glycerol oxidation (GOR), and aim to provide an overview of the GOR process and the intrinsic structural-activity correlation for inspiring future work in this field. The review is dissected into three sections. We will first introduce the recent efforts of designing more efficient and selective catalysts for GOR, especially toward the production of value-added products. Then, we will summarize the current understandings about the reaction network based on the ex-situ and in-situ spectroscopic studies as well as the theoretical works. Lastly, we will select some representative examples of creating real electrochemical devices for the valorization of glycerol. By summarizing these previous efforts, we will provide our vision of future directions in the field of GOR toward real applications. Recent advances of catalyst designs, mechanistic understandings and assembled devices for the electrocatalytic glycerol oxidation into value-added products are reviewed. The detailed activities, selectivities and reaction pathways on different catalysts are summarized.