Hollow Cobalt Sulfide Nanocapsules for Electrocatalytic Selective Transfer Hydrogenation of Cinnamaldehyde with Water

Designing nanostructured electrocatalysts for selective transfer hydrogenation of α, β-unsaturated aldehydes with water as the hydrogen source is highly desirable. Here, a facile self-templating strategy is designed for the synthesis of CoS₂ and CoS₂-x nanocapsules (NCs) as efficient cathodes for selective transfer hydrogenation of cinnamaldehyde, a model α, β-unsaturated aldehyde. The hollow porous structures of NCs are rich in active sites and improve mass transfer, resulting in high turnover frequency. The specific adsorption of the styryl block on pristine CoS₂ NCs is conducive to the selective formation of half-hydrogenated hydrocinnamaldehyde with 91.7% selectivity, and the preferential adsorption of the C = O group induced by sulfur vacancies on defective CoS₂-x NCs leads to the full-hydrogenated hydrocinnamyl alcohol with 92.1% selectivity. A cross-coupling of carbon and hydrogen radicals may be involved in this electrochemical hydrogenation reaction. Furthermore, this selective hydrogenation method is also effective for other α, β-unsaturated aldehydes, illustrating the universality of the method.