Electro- and Photocatalytic Hydrogen Evolution from Water Supported by octahedral Ni6L18 based connected 1D coordination cages

Abstract

Recently, there is gradual increase in demand for renewable energy due to global energy crisis and hydrogen production from water offers a promising approach. Herein, we report the design and synthesis of an octahedral Ni6L18 based one dimensional coordination network derived from a N-donor tripodal silane ligand MeSi(3-py)3 and study of their electrocatalytic and photocatalytic activity for hydrogen evolution from water. The 1-D cage (1) is highly soluble in water and organic solvents like acetonitrile, methanol etc. The UV-Visible studies reveals that the complex is highly stable in solution. The electrochemical analysis of 1 in aqueous BR buffer solution have revealed that it exhibits two quasi reversible redox couples Ni+2/Ni+1 and Ni+3/Ni+2. Further, the Pourbaix diagram and pH dependent LSV studies reveal that 1 exhibits the proton coupled electron process (PCET) which is vital for proton reduction reaction. Further, acetic acid dependent cyclic voltammetry were performed which revealed the TOF of 53s-1 for the H2 evolution reaction from water catalyzed by 1. Remarkably, the photocatalytic activity performed for 69hr using 100μM, 150μM, and 200 μM concentrations of 1, [Ru(byp)3]+2 as PS and ascorbic acid as sacrificial electron donor resulted in a TON of 1230.