A computational investigation into the electron-transfer kinetics and thermodynamics of hydrogen gas production by Ni(S2C2H2)2, Ni(Se2C2H2)2, and Ni(Te2C2H2) complexes

Abstract

Fossil fuels are rapidly being depleted and releasing great amounts of greenhouse gases, causing harmful effects to the environment. Renewable energy such as solar energy is an alternative option instead of using fossil fuels. However, storing the energy harvested as H2 by the electrolysis of H2O requires an effective, cheap catalyst to be practical. Thus, Ni catalysts are a valid option to produce hydrogen gas. In this study, the thermodynamics, and kinetics of ET for the electrocatalytic production of H2 by analogous Ni-bis(dithiolene), Ni-bis(diselenolene), and Ni-bis(ditellurolene) complexes were studied using DFT. Thermodynamically, it was found that all three catalysts catalyze the formation of H2 with similar energetic cost. However, for release of H2 the catalysts must be doubly protonated and triply reduced. While the first two reductions occur with low Gibbs activation energies the third reduction does not. Therefore, if a third reduction is required for electrocatalytic H2 production a large overpotential would be expected from our predictions.