Elementary kinetics of nitrogen electroreduction to ammonia on late transition metals

Abstract

Nitrogen reduction reaction barriers calculated by density functional theory quantify NRR activity and selectivity challenges.

Liquefied Sunshine: Transforming Renewables into Fertilizers and Energy Carriers with Electromaterials

“…This poor understanding of the details of kinetic phenomena in electrochemical reactions means that the estimation of overpotentials is usually based on the thermodynamic steps between intermediates, i.e., the description of the largest endergonic step in the free energy profile of the reaction; this has a more direct relationship to the equilibrium potentials rather than the kinetic barriers. Recent studies in the estimation of NRR kinetics through the calculation of potential dependent electrochemical barriers show values greater than 1 eV in a series of late transition metal surfaces . However, some of these values are in considerable disagreement with observed experimental results (though it must be noted that many experimental results are questionable, as discussed above).…”

Atomic Modulation, Structural Design, and Systematic Optimization for Efficient Electrochemical Nitrogen Reduction

“…Many transition metals without defects, especially late transition metals, have the ability to convert N 2 to NH 3 . Both associative and dissociative pathways were assessed using pure late transition metals and the latter pathway was found to have lower energy barriers than the former . A “kinetic volcano” plot was obtained, in which Rh and Fe metals were calculated to be advantageous for NRR as they had the lowest kinetic barriers.…”

“…Specifically, such electrocatalysts are usually compounds rather than pure metals. Moreover, the components, crystal planes, phases, spatial structures on the nano/microscale, etc., are often complex and hard to simulate in calculation models . Thus, experiments ought to be combined with theoretical research for designing efficient pure metal electrocatalysts.…”

“…[84] Both associative and dissociative pathways were assessed using pure late transition metals and the latter pathway was found to have lower energy barriers than the former. [85] A "kinetic volcano" plot was obtained, in which Rh and Fe metals were calculated to be advantageous for NRR as they had the lowest kinetic barriers. In a real electrocatalyst, however, such principles may be broken because of multiple factors affecting the system.…”

“…Moreover, the components, crystal planes, phases, spatial structures on the nano/microscale, etc., are often complex and hard to simulate in calculation models. [85] Thus, experiments ought to be combined with theoretical research for designing efficient pure metal electrocatalysts. For example, based on the intrinsic dinitrogen adsorption/activation ability, Ru, [86] RuPt alloy, [87] and PdRu alloy [88] have been developed for synergistically catalyzing NRR.…”