Mononuclear nickel and copper complexes as electrocatalyst for generation of hydrogen from acetic acid

Ever increasing use of conventional energy and demand of clean renewable energy inspire many researchers to produce effective systems for hydrogen generation. Herein we report two mononuclear complexes, [NiL] (Complex 1) and [CuL] (Complex 2), where H2L is 1,1 '-(1E,1 ' E)-(propane-1,2-diylbis(azan-1-yl-1-ylidene))bis (methan-1-yl-1-ylidene)dinaphthalen-2-ol, as electrocatalyst for hydrogen evolution reaction using acetic acid as the substrate. Both of the complexes have been synthesized under mild conditions and characterized by several methods. Single crystal X-ray structure of Complex 1 shows square planar geometry around nickel center. These complexes have effectively been used to reduce proton to generate hydrogen. Different control experiments have been carried out to understand the role of these catalysts and find their relevance in this regard. Turnover fre-quency (TOF) values for 1 and 2 have been determined as 653.1 and 777.5 s- 1, respectively. Hydrogen is evolved via reduction of metal center followed by formation of metal hydride species.

Automated summary

This article reports two mononuclear complexes, [NiL] (Complex 1) and [CuL] (Complex 2), as electrocatalysts for hydrogen evolution reaction using acetic acid as the substrate. These complexes have been synthesized under mild conditions and characterized by various methods. The X-ray structure of Complex 1 shows a square planar geometry around the nickel center. Both complexes effectively reduce protons to generate hydrogen. Control experiments have been carried out to understand the role of these catalysts and their relevance in this regard. The turnover frequency (TOF) values for Complex 1 and 2 are determined as 653.1 and 777.5 s-1, respectively. Hydrogen is evolved through the reduction of the metal center followed by the formation of metal hydride species.