Ionic Liquid Dopant Induced 3D Hierarchical CuO Nanostructures with Doped Heteroatoms and Highly Dispersed Ag for Electrochemical Upgrading of 5-Hydroxymethylfurfural

The electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) has received increasing attention due to its carbon-neutral and value-added chemical properties, and the development of electrocatalyst with highly active and selective is crucial. Highly dispersing metal atoms throughout the catalyst can maximize the catalytic efficiency. Here, we synthesized a 3D hierarchical CuO nanostructure induced by ionic liquid with heteroatoms doping and Ag dispersing (Ag-CuO@IL), and this self-supported catalyst can reach 10 mA cm-2 at only 1.33 V vs RHE and achieved HMF conversion of 98.5 %, FDCA yield of 97.1 % and Faraday efficiency of 92.2 %. The excellent catalytic performance of Ag-CuO@IL for HMFOR is attributed to the doped heteroatoms derived from ILs to promote electron redistribution and the generated oxygen vacancies induced by IL anions to highly disperse Ag. Also, the catalyst was the nanosheet-assembled spherical clusters with 3D nanostructure, which exposed a large number of active sites. Density functional theory calculations showed that Ag-CuO@IL possessed moderate adsorption strengths of HMF and OH-, thus facilitating the desorption of the products in the reaction process. The design that induced by ionic liquid dopant not only provides an effective and green mean for HMFOR, but also has the large potential to guide the synthesis of other catalysts with improved performances in various applications.