Liquid Versus Gas Phase Dehydrogenation Of Formic Acid Over Co@N-Doped Carbon Materials. The Role Of Single Atomic Sites

N-doped carbon nanomaterials containing certain transition metals have recently attracted significant interest as the promising noble-metal-free composites for a variety of applications, including in particular catalytic generation of molecular hydrogen from formic acid (FA). This reaction is increasingly becoming essential for advanced hydrogen energy technologies in the area of energy storage and conversion devices. Here, we report a comparative study on FA decomposition over Co@N-doped carbon materials obtained by a variety of synthetic approaches. The reaction was examined under both liquid-and gas-phase conditions. Most notably, it has been shown that a technologically rather simple method for the preparation of Co@N-doped carbon, which is based on physical mixing (solid-state grinding) of cobalt(II) salts, nitrogen-containing ligands and carbon black, followed by pyrolysis, leads to the desired and highly competitive catalytic performance. The key role of single atomic catalytic sites is discussed to provide the catalytic properties of Co@N-carbon materials toward FA dehydrogenation regardless of peculiarities of their preparation method.