Hydrogen has various uses in today’s economy ranging from production of fossil fuels and ammonia to use as a fuel source. Currently, the production of hydrogen on an industrial level is achieved by steam reformation which produces carbon monoxide as a product along with hydrogen. The ideal reaction of water splitting has yet to be feasibly obtained on an industrial level either do to large overpotentials of catalysts or cost limitations. Work has been done with both homogeneous and heterogeneous catalysts to make this reaction more feasible. Heterogeneous catalyst provide higher activity, with the current gold standard being platinum. To this end we employed two new nickel catalysts based off the diacetylbis (N(4)-methylthiosemicarbazone) (ATSM) framework and attached them to a working glassy carbon electrode. The new compounds were different from the parent compound of NiATSM via the implementation of a methyl group to generate the tertiary amine derivative, NiATSDM, and installment of a –CH2CF3 group off each pendent amine, NiATSM-F6. All complexes required cycling to achieve optimal activity. The overpotential of NiATSDM and NiATSM was found to be 0.45 V, whereas NiATSM-F6 was drastically higher with an overpotential of 0.77 V. This would suggest an electron withdrawing substituent lowers the basicity of the ligand too much to achieve optimal activity. However, upon closer investigation it was found that the surface morphology played a critical role in activity. Prior to cycling, NiATSDM and NiATSM had micro-crystalline surfaces which then became more amorphous after cycling to peak activity. The surface morphology of the NiATSM-F6 compound was found to not crystallize on the electrode surface and did not become amorphous after cycling which limits its ability as a catalyst.

Heterogeneous hydrogen evolution with novel nickel ATSM catalysts and the effect of surface morphology

256th National Meeting (2018)

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