Photochemical H2 Evolution from Bis(diphosphine)nickel Hydrides Enables Low-Overpotential Electrocatalysis

• DOI: 10.1021/jacs.1c10628
• Publication Date: 2021-12-08T16:34:23Z
• Authors: Bethany M. Stratakes; Kaylee A. Wells; Daniel A. Kurtz; Felix N. Castellano; Alexander J. M. M...
• Keywords: Overpotential; Homolysis

Molecules capable of both harvesting light and forming new chemical bonds hold promise for applications in the generation solar fuels, but such first-row transition metal photoelectrocatalysts are lacking. Here we report nickel H2 evolution, leveraging visible-light-driven photochemical evolution from bis(diphosphine)nickel hydride complexes. A suite experimental theoretical analyses, including time-resolved spectroscopy continuous irradiation quantum yield measurements, led to a proposed mechanism involving short-lived singlet excited state that undergoes homolysis Ni-H bond. Thermodynamic analyses provide basis understanding predicting observed photoelectrocatalytic by 3d based catalyst. Of particular note is dramatic change electrochemical overpotential: dark, complexes require strong acids therefore high overpotentials electrocatalysis; under illumination, use weaker at same applied potential results more than 500 mV improvement overpotential. New insight into photochemistry thus enables without overpotential (at thermodynamic or 0 overpotential). This catalyst system does not sacrificial reductants light-harvesting semiconductor materials produces rates similar molecular catalysts attached silicon.