Controlled dispersion of Ni catalyst on N-doped carbon support for stable and selective hydrogen production from formic acid

Formic acid is a liquid organic hydrogen carrier from which hydrogen can be released together with CO2 by catalytic decomposition. The development of supported Ni catalysts for H-2 production is important. Here, the effects of Ni state/dispersion are considered. For this purpose, three samples were prepared with about 3 wt% Ni deposited on porous N-doped carbon. The first sample contained predominantly Ni nanoparticles (similar to 2 nm), the second contained Ni clusters (<1 nm), and the third - single-atom Ni sites. The catalysts showed close activity in the gas-phase reaction. However, a minimum apparent activation energy of 105 kJ/mol and a maximum selectivity towards H-2 production of 99% were achieved for the single-atom Ni catalyst. The nature of its singleatom sites was established to correspond to Ni-N-4 and Ni-O-4, which showed greater stability under the conditions of the catalytic reaction.