The Reduction of Various Nitrides under Hydrogen: Ni3N, Cu3N, Zn3N2 and Ta3N5

Chemical looping of metal nitride catalysts: low-pressure ammonia synthesis for energy storage

“…At one extreme, thermally unstable nitrides – such as Co 3 Mo 3 N, Ni 3 N, Cu 3 N and Zn 3 N 2 – have been shown to yield much NH 3 via denitridation with H 2 at about 250–400 °C. 44 , 46 However, the latter three materials are too unstable to be regenerated with N 2 at 1 bar 46 and a completely reversible recycling of Co 3 Mo 3 N from the formed Co 6 Mo 6 N requires long-time heating for 4 h in H 2 /N 2 . 44 On the other extreme, some more stable metal nitrides, when reacted with H 2 , absorb hydrogen reversibly yielding mixtures of metal imide, amide and hydride ( e.g.…”

“…This phenomena is well known from the interaction of adsorbates at transition-metal surfaces. 52 While we did not include Ni 3 N, Cu 3 N and Zn 3 N 2 in this analysis due to limited thermodynamic data, the high NH 3 yields with these unstable metal nitrides 46 can be understood due to an even higher number of d-electrons, relative to Fe 4 N. We suggest that the trade-off between NH 3 evolution and N 2 reduction may be optimized for doped transition-metal nitrides by targeting properties intermediate to those of Mn and Fe, that is, an N d E d of about –50 eV. Since the correlation of d-state occupancy and nitride reactivity is linked through the stability of the metal–nitrogen bond, for a ternary system N d E d may be defined in first approximation as the arithmetic average of the value for the metals that form metal–nitrogen bonds.…”

“…Ni 3 N, Cu 3 N, Zn 3 N 2 and Ta 3 N 5 may liberate 30, 25, 23, and 13 mol% of their lattice nitrogen as NH 3 when reacted for at least 30 min at 250, 250, 400, and 700 °C, respectively. 46 Ammonia yields decrease when reacting H 2 with more stable nitrides: such as to 8 mol% with Co 3 Mo 3 N for 60 min at 400 °C. 44 Manganese nitrides can be formed from N 2 at 1 bar, as shown with Fig.…”

Facile preparation of copper nitride powders and nanostructured films

“…The total pore volume is B0.038692 cm 3 g À1 and reinforces the premise that most of the surface area of the sample is external and that the majority of structural nitrogen species are located in the bulk (as lattice N atoms) rather than on the (internal or external) surface of the material. 54 Crystal structure from powder X-ray diffraction data. Rietveld refinement 55 of the structure of the copper nitride powder obtained at 300 1C (sample 3) was performed using the anti-ReO 3 structure of Cu 3 N reported in ref.…”

DFT-D3 study of H2 and N2 chemisorption over cobalt promoted Ta3N5-(100), (010) and (001) surfaces

“…The interstitial nitrogen was found to be labile and reactive to hydrogen that generates ammonia under reducing conditions. 6,11 The porous structure of Ta 3 N 5 offers the possibility of adsorbing metal atoms to its structure. The effect of co-adsorbed cobalt atoms with respect to the adsorption of H 2 and N 2 has not been previously studied theoretically.…”