Electrocatalytic selectivity for nitrogen reduction vs. hydrogen evolution: a comparison of vanadium and cobalt oxynitrides at different pH values

Abstract

The electrocatalytic nitrogen reduction reaction (NRR) is of significant interest as an environmentally friendly method for NH3 production for agricultural and clean energy applications. Selectivity of NRR vis-à-vis the hydrogen...

Stability and activity of titanium oxynitride thin films for the electrocatalytic reduction of nitrogen to ammonia at different pH values

“…Using analogous plane-wave DFT results, the stability of the critical diazenide *NNH surface configuration (computations assume zero applied potential pH = 0 to facilitate comparison) was compared for the various 3d metal oxynitrides our group has studied: 17 rs-TiO x N y (001), rs-VO x N y (001), zb-CoO x N y (110), and zb-CoN(110), zb = zinc blende.…”

“…In previous experimental/computational studies of V-oxides and -oxynitrides it was concluded that N 2 /water binding was competitive under catalytic conditions. 17–19 In support of this hypothesis, N 2 and water binding energies for model surfaces of varying coordination number and formal oxidation state were evaluated. 17–19 N 2 binding was found to be favored for lower coordination numbers and less positive metal formal oxidation states, bonding characteristics that enhance π-backbonding from the metal to the N 2 π* orbitals.…”

“…17–19 In support of this hypothesis, N 2 and water binding energies for model surfaces of varying coordination number and formal oxidation state were evaluated. 17–19 N 2 binding was found to be favored for lower coordination numbers and less positive metal formal oxidation states, bonding characteristics that enhance π-backbonding from the metal to the N 2 π* orbitals. Interestingly, while the binding of water to rs-TiO x N y (001) and rs-VO x N y (001) surfaces is commensurate (−0.33 vs. −0.28 eV, respectively), π-backbonding in the titanium material is much stronger (−1.09 vs. −0.14 eV).…”

Recent Progress in Electrochemical Nitrogen Reduction on Transition Metal Nitrides

“…The most prospective candidates are ZrN, NbN, CrN, and VN enclosed with the RS(100) facets, which are calculated to be able to produce ammonia at −0.76 V, −0.65 V, −0.76 V, and −0.51 V, respectively (Figure 3A). [46] Most importantly, hydrogen evolution reaction (HER) is no longer the competing reaction on these TMN catalysts [80] . On the contrary, other TMNs, as well as the above‐mentioned ones in the ZB crystal structure or facets show poor or no catalytic activity, and/or catalyst decomposition occurs [44–46] .…”

“…[46] Most importantly, hydrogen evolution reaction (HER) is no longer the competing reaction on these TMN catalysts. [80] On the contrary, other TMNs, as well as the above-mentioned ones in the ZB crystal structure or facets show poor or no catalytic activity, and/or catalyst decomposition occurs. [44][45][46] To further explore new candidates for ENRR at ambient conditions via the MvK mechanism, the catalytic performance of 23 TMNs with the ZB(110) facets are investigated.…”