Experimental and theoretical studies of ammonia generation: Reactions of H2 with neutral cobalt nitride clusters

Ammonia generation through reaction of H2 with neutral cobalt nitride clusters in a fast flow reactor is investigated both experimentally and theoretically. Single photon ionization at 193 nm is used to detect neutral cluster distributions through time-of-flight mass spectrometry. ComNn clusters are generated through laser ablation of Co foil into N2/He expansion gas. Mass peaks ComNH2 (m = 6, 10) and ComNH3 (m = 7, 8, 9) are observed for reactions of H2 with the ComNn clusters. Observation of these products indicates that clusters ComN (m = 7, 8, 9) have high reactivity with H2 for ammonia generation. Density functional theory (DFT) calculations are performed to explore the potential energy surface for the reaction Co7N + 3/2H2 → Co7NH3, and a barrierless, thermodynamically favorable pathway is obtained. An odd number of hydrogen atoms in ComNH3 (m = 7, 8, 9) probably come from the hydrogen molecule dissociation on two active cobalt nitride clusters based on the DFT calculations. Both experimental observ...