Extracting Features of Active Transition Metal Electrodes for NO Electroreduction with Catalytic Matrices

Abstract

Electrocatalytic reduction of oxidized nitrogen compounds (NO x ) promises to help rebalance the nitrogen cycle. It is widely accepted that nitrate reduction to NH4 +/NH3 involves NO as an intermediate, and NO hydrogenation is the potential-limiting step of NO reduction. Whether *NO hydrogenates to *NHO or *NOH is still a matter of debate, which makes it difficult to optimize catalysts for NO x electroreduction. Here, “catalytic matrices” are used to swiftly extract features of active transition metal catalysts for NO electroreduction. The matrices show that active catalysts statistically stabilize *NHO over *NOH and have undercoordinated sites. Besides, square-symmetry active sites with Cu and other elements may prove active for NO electroreduction. Finally, multivariate regressions are able to reproduce the main features found by the matrices, which opens the door for more sophisticated machine-learning studies. In sum, catalytic matrices may ease the analysis of complex electrocatalytic reactions on multifaceted materials.

Cation Effects on the Adsorbed Intermediates of CO2 Electroreduction Are Systematic and Predictable

“…Again, a Monkhorst–Pack mesh was used to sample the Brillouin zone but with grid size (4 × 4 × 1). For explicit solvation, stepwise addition of H 2 O molecules was used. , The additional stabilizing energy provided by each additional water molecule solvating the CO 2 reduction intermediate A , Ω A n = E *[ A +H 2O ] + E * – E * A – E *H 2 O = Δ E [ A +H 2 O] – Δ E A , is compared to the stabilizing energy provided when the water molecule is solvated by other water molecules, Ω H 2 O , and if Ω A n < Ω H 2 O it is assumed that the intermediate is solvated and another water molecule is added. In general, *COOH is solvated via hydrogen bonding by one water molecule ( n = 1), whereas *CO is not solvated via hydrogen bonding ( n = 0).…”

“…An affordable approach is “ micro-solvation ”, in which a few explicit solvent and/or electrolyte species are included around the adsorbate. In the case of CO 2 RR and other reactions with small adsorbed intermediates, an iterative microsolvation model has been proposed that provides a good approximation to experimental catalytic activity results. − …”

“…In the case of CO 2 RR and other reactions with small adsorbed intermediates, an iterative microsolvation model has been proposed that provides a good approximation to experimental catalytic activity results. 45 − 47 …”

Electrocatalysis of nitrogen pollution: transforming nitrogen waste into high-value chemicals

“…67,79–84 Recently, the electrocatalysts design and optimization based on theoretical calculation advanced by leaps and bounds, which has decreased the time cost compared with the “trial and error” approach. 85–92 Such development helps us narrows the scope of potential electrocatalyst candidates, pushing the realization of the electrocatalytic NW recycling. However, electrocatalysts have not yet been customized for practical application because of the following technical challenges: (1) the time- and voltage-dependent stability of faradaic efficiency when directly coupled with renewable energy systems; and (2) the low-cost mass preparation of catalysts.…”