Interfacial Asymmetrically Coordinated Zn-MOF for High-Efficiency Electrosynthetic Oxime.

Oximes are important intermediates for various chemicals synthesis such as pharmaceuticals, among which one vital precursor for producing neurological disease, antimicrobial and anticancer agents is piperidone oxime (PDO). Compared with conventional thermocatalytic method, it's more attractive to synthesize PDO via green electrocatalytic technology especially utilizing waste nitrogen oxides gas as nitrogen source. However, there are great challenges in catalyst design for high-efficiency electrosynthetic oxime due to the low electron transport rate and multiple competing reactions. Herein, we propose an interfacial coordination strategy based on metal-organic frameworks (MOF) electrocatalyst for the first time to promote oxime electrosynthesis, by building Zn-O bridges between graphite felt (GF) and zeolitic imidazolate framework (ZIF-7/CGF). Specially, ZIF-7/CGF delivers a Faraday efficiency (FE) of 75.9 % with yield up to 73.1 % for 1-methyl-4-piperidone oxime, which is far superior to the catalyst without Zn-O bridges (a FE of 10.7 % and yield of 10.3 %). In-depth mechanism study shows that the introducing Zn-O bridges can promote the electron transfer and induce Zn sites transforming into distorted tetrahedron (Zn-N3O) coordination mode, which benefits for intermediates adsorption and conversion. The developed strategy presents wide universalities towards various oximes electrosynthesis and adapts to other MOF materials (ZIF-8, ZIF-4). This work provides new insights for electrosynthetic organic chemicals and upgrading nitrogen cycle through rational design surficial coordinated electrocatalysts.