Heteroatom Introduction and Electrochemical Reconstruction on Heterostructured Co-Based Electrocatalysts for Hydrogenation of Quinolines

Electrocatalytic hydrogenation (ECH) of quinoline provides an eco-friendly and prospective route to achieve the highly value-added generation of 1,2,3,4-tetrahydroquinoline (THQ). Co element has been proven to be the efficient catalytic site for ECH of quinoline, but the rational regulation of the electronic structure of active Co site to improve the activity is still a challenge. Herein, the hierarchical core–shell structure consisting of NiCo-MOF nanosheets encapsulated Cu(OH) 2 nanorods (Cu(OH) 2 @CoNi-MOF) is constructed. The heterojunction promotes the transfer of interfacial charge and optimizes the electronic structure of the Co site. The introduction of Ni significantly increases the binding between Co and Cu, preventing the exfoliation of Co sites from Cu(OH) 2 core, and reducing the reaction energy barrier of rate-determining step, thus resulting in superior reactivity and durability. Besides, electrochemical reconstruction further modulates the electronic structure of Co by forming the multi-metallic compound with a low valence state (NiCoCu), achieving an optimal performance with a conversion of 99.5% and THQ selectivity of 100%. A flow-cell system is assembled, demonstrating the prospect for industrial application.