In(III) Metal-Organic Framework Incorporated with Enzyme-Mimicking Nickel Bis(dithiolene) Ligand for Highly Selective CO Electroreduction.

Inspired by the exciting physical/chemical properties in metal-organic frameworks (MOFs) of the redox-active tetrathiafulvalene (TTF) ligands, nickel bis(dithiolene-dibenzoic acid), [Ni(CS(CHCOOH))], has been designed and developed as an inorganic analogue of the corresponding TTF-type donors (such as tetrathiafulvalene-tetrabenzoate, TTFTB), where a metal site (Ni) replaces the central C═C bond. In this work, [Ni(CS(CHCOOH))] and In have been successfully assembled into a three-dimensional MOF, (MeNH){In-[Ni(CS(CHCOO))]}·3DMF·1.5HO (, DMF = -dimethylformamide), with satisfying chemical and thermal stabilities. With the combination of reversible redox activity and unsaturated metal sites originated from [Ni(CS(CHCOOH))], showed a significantly enhanced performance in electrocatalytic CO reduction compared with the isomorphic MOF, (MeNH)[In-(TTFTB)]·0.7CHOH·DMF (, with TTFTB ligand). More importantly, by mimicking the active [NiS] sites of formate dehydrogenase and CO-dehydrogenase, a prominently higher conversion rate and Faradaic efficiency (FE), with FE increasing from 54.7% to 89.6% (at -1.3 V vs RHE, = 36.0 mA cm), were achieved in . Mechanistic investigations further confirm that [NiS] can serve as a CO binding site and efficient catalytic center. This unprecedented effect of redox-active nickel dithiolene-based MOF catalysts on the performance of electroreduction of CO provides an important strategy for designing stable and efficient crystalline enzyme-mimicking catalysts for the conversion of CO into high-value chemical stocks.