Electrochemical carbon dioxide reduction to fuels presents one of the great challenges in chemistry. Herein we present an understanding of trends in electrocatalytic activity for carbon dioxide reduction over different metal catalysts that rationalize a number of experimental observations including the selectivity with respect to the competing hydrogen evolution reaction. We also identify two design criteria for more active catalysts. The understanding is based on density functional theory calculations of activation energies for electrochemical carbon monoxide reduction as a basis for an electrochemical kinetic model of the process. We develop scaling relations relating transition state energies to the carbon monoxide adsorption energy and determine the optimal value of this descriptor to be very close to that of copper.

Amides are common functional groups that have been well studied for more than a century.1 They serve as the key building blocks of proteins and are present in an broad range of other natural and synthetic compounds. Amides are known to be poor electrophiles, which is typically attributed to resonance stability of the amide bond.1,2 Whereas Nature can easily cleave amides through the action of enzymes, such as proteases,3 the ability to selectively break the C–N bond of an amide using synthetic chemistry is quite difficult. In this manuscript, we demonstrate that amide C–N bonds can be activated and cleaved using nickel catalysts. We have used this methodology to convert amides to esters, which is a challenging and underdeveloped transformation. The reaction methodology proceeds under exceptionally mild reaction conditions, and avoids the use of a large excess of an alcohol nucleophile. Density functional theory (DFT) calculations provide insight into the thermodynamics and catalytic cycle of this unusual transformation. Our results provide a new strategy to harness amide functional groups as synthons and are expected fuel the further use of amides for the construction of carbon–heteroatom or carbon–carbon bonds using non-precious metal catalysis.

Linear scaling relationships between the adsorption energies of CO2 reduction intermediates pose a fundamental limitation to the catalytic efficiency of transition-metal catalysts. Significant improvements in CO2 reduction activity beyond transition metals require the stabilization of key intermediates, COOH* and CHO* or COH*, independently of CO*. Using density functional theory calculations, we show that the doped sulfur edge of MoS2 satisfies this requirement by binding CO* significantly weaker than COOH*, CHO* and COH*, relative to transition metal surfaces. The structural basis for the scaling of doped sulfur edge of MoS2 is due to CO* binding on the metallic site (doping metal) and COOH*, CHO* and COH* on the covalent site (sulfur).Linear scaling relations still exist if all the intermediates bind to the same site, but the combined effect of the two binding sites result in an overall deviation from transition-metal scaling lines.This principle can be applied to other metal/p-block materials. We rationalize the weak binding of CO* on the sulfur site with distortion/interaction and charge density difference analyses.