Growth mechanism of graphite-carbon encapsulated nickel catalysts and curvature effect of carbon layer on the performance of catalytic hydrogenation

This research focuses on the growth mechanism from organometallic coordination polymers precursor to encapsulated catalyst, which contributes to the guiding for the directional design and controlled preparation of the catalyst. Decomposition of organic matter, reduction of nickel, and dissolution/segregation of carbon in the nickel nanoparticles are three main steps for the conversion of Ni@C-OCPs to Ni@C under pyrolysis. The contents of reducing atmosphere during pyrolysis were reduced via selecting organic ligands with smaller molecular and higher C-H ratios. Thus, Ni@C-600 with smaller particle size and larger curvature of the carbon layer surface was obtained. Kinetic experiments showed that it corresponded to a lower apparent activation energy. In addition, density function theory simulation verified that the optimization of the electronic structure generated by the large curvature graphite carbon layer was one of the sources of its excellent activity.