Computational Investigation into the Ni(SeNHC(CN)) and Ni(SNHC(CN)) Complexes as Potential Catalysts for Hydrogen Production.

To reduce our carbon footprint, we must look at alternative non-carbon-containing fuels to prevent continued global climate change. One environmentally friendly alternative fuel is molecular hydrogen. Herein the Ni(SeNHC(CN)) complex was studied using DFT to determine the thermodynamics associated with the electrocatalytic formation of H(g). From the calculated thermodynamics, it appears that the Ni(SeNHC(CN)) complex is predicted to catalyze the production of H gas under mildly reducing conditions relative to the SHE. Notably, the thermodynamics are better than the values calculated for the analogous Ni(SNHC(CN)) complex which has been shown experimentally to catalyze the formation of H gas in aqueous solution. Regarding possible kinetic reactivity, the HOMO-LUMO gap energies were calculated. From the gap energies, it is expected that the Se-containing compounds would be more reactive to electron transfer in the third reduction step, meaning therefore that a smaller overpotential would be needed to drive the reduction of Red2-H relative to Red2-H in agreement with past experimental work. Thus, the use of Se in such compounds may offer a means to improve the catalysts for H production.