Boosted Electrocatalytic Hydrogenation of Quinoline over an Electroreconstructed Cobalt Transition Metal-Based Catalyst

Electrocatalytic quinoline hydrogenation reaction (EQHR) for producing high-value-added 1,2,3,4-tetrahydroquinoline (THQ) has garnered considerable attention. Herein, we designed a hierarchical cobalt-based nanosheet catalyst (r-Co(OH)2) on the Ni-foam substrate by the electrodeposition and electroreconstruction strategies, which achieved exceptional performance with 99.5% conversion of quinoline and nearly 100% selectivity of THQ at a potential of -1.2 V vs Hg/HgO. In situ electrochemical experiments demonstrated that the low-valence-state Co sites from the electroreconstruction are the active sites in the reaction interface. Density functional theory (DFT) calculations revealed that the improved electrocatalytic performance originates from the enhanced adsorption of quinoline and the appropriate generation of active hydrogen, as well as the reduced energy barrier after electroreconstruction. Furthermore, a small-scale amplification system was designed to satisfy the requirements of industrial applications. Both the synthesis of a pilot-scale r-Co(OH)2 electrode and the electrolysis of EQHR were performed in the diaphragm frame cell, achieving the full-process control of electrode preparation and electrolysis process. This study provides an innovative idea for the rational design and amplification of an electrode to produce high-value chemicals in an industrial reactor.