Motivated by in silico predictions that Co,Rh, and Ir dopants would lead to low overpotentials to improve OER activity of Ni-based hydroxides,wereport here an experimental confirmation on the altered OER activities for as eries of metals (Mo,W ,F e, Ru, Co,Rh, Ir) doped into g-NiOOH. The in situ electrical conductivity for metal doped g-NiOOH correlates well with the trend in enhanced OER activities. Density functional theory (DFT) calculations were used to rationalizethe in situ conductivity of the key intermediate states of metal doped g-NiOOH during OER. The simultaneous increase of OER activity with intermediate conductivity was later rationalized by their intrinsic connections to the double exchange (DE) interaction between adjacent metal ions with various do rbital occupancies,s erving as an indicator for the key metal-oxoradical character,and an effective descriptor for the mechanistic evaluation and theoretical guidance in design and screening of efficient OER catalysts.

Selective oxidation to synthesize nitriles is critical for feedstock manufacturing in the chemical industry. Current strategies typically involve substitutions of alkyl halides with toxic cyanides or the use of strong oxidation reagents (oxygen or peroxide) under ammoxidation/oxidation conditions, setting considerable challenges in energy efficiency, sustainability, and production safety. Herein, we demonstrate a facile, green, and safe electrocatalytic route for selective oxidation of amines to nitriles under ambient conditions, assisted by the anodic water oxidation on metal-doped α-Ni­(OH)2 (a typical oxygen evolution reaction catalyst). By controlling the balance between co-adsorption of the amine molecule and hydroxyls on the catalyst surface, we demonstrate that Mn doping significantly promotes the subsequent chemical oxidation of amines, resulting in Faradaic efficiencies of 96% for nitriles under ≥99% conversion. This anodic oxidation is further coupled with cathodic hydrogen evolution for overall atomic economy and additional green energy production.

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(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ], 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(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ] and In 3+ have been successfully assembled into a three-dimensional MOF, (Me, with satisfying chemical and thermal stabilities. With the combination of reversible redox activity and unsaturated metal sites originated from [Ni(C 2 S 2 (C 6 H 4 COOH) 2 ) 2 ], 1 showed a significantly enhanced performance in electrocatalytic CO 2 reduction compared with the isomorphic MOF, (Me 2 NH 2 + )[In III -(TTFTB)]•0.7C 2 H 5 OH•DMF (2, with TTFTB ligand). More importantly, by mimicking the active [NiS 4 ] sites of formate dehydrogenase and CO-dehydrogenase, a prominently higher conversion rate and Faradaic efficiency (FE), with FE HCOO − increasing from 54.7% to 89.6% (at −1.3 V vs RHE, j HCOO − = 36.0 mA cm −2 ), were achieved in 1. Mechanistic investigations further confirm that [NiS 4 ] can serve as a CO 2 binding site and efficient catalytic center. This unprecedented effect of redox-active nickel dithiolene-based MOF catalysts on the performance of electroreduction of CO 2 provides an important strategy for designing stable and efficient crystalline enzyme-mimicking catalysts for the conversion of CO 2 into high-value chemical stocks.

A confined electro-catalysis strategy for enhanced performance in electrochemical nitrogen reduction reaction was achieved via the construction of carbon nanotubes (CNTs) inserted metal–organic frameworks (MOFs).