A Trimetallic Cu(II) Derivative as an Efficient and Stable Electrocatalyst for Reduction of Proton to Molecular Hydrogen

A trinuclear copper(II) complex, namely [Cu-3(L)(2)(CF3COO)(2)] (1) is afforded integrating a 'compartmental' Schiff base, H2L [where H2L = N,N '-bis(salicylidene)-1,3-propanediamine] and fully characterized. Complex 1 is implemented for electrocatalytic proton reduction to originate molecular hydrogen in a homogenous system. The electrochemical study involving CV (cyclic voltammetry), CPE (controlled potential electrolysis) and GC (gas chromatography) reveals that in homogeneous system, 1 is highly active towards proton reduction in presence of trifluoro acetic acid as a proton source. Following CPE at - 1.8 V vs Ag/AgCl, the headspace gas is sampled and gas chromatography is carried out to quantify the amount of hydrogen discharged. The ratio of theoretical H-2 production from charge aggregation during electrolysis to the practical amount of H-2 resolved on GC is yielded a Faradaic efficiency value of 87%. Moreover, an extended bulk electrolysis experiment carried out for 35 h illustrates the presence of a stable catalytic system in which 230 C of charge is accumulated. As a consequence, this efficient and stable H-2 evolution obtained using a Cu(II) derivative (Cu-II is cheap and earth abundant) has shown that the synthesis of judiciously designed copper complex is a promising strategy towards potential catalysts from proton reduction. Graphic Abstract [GRAPHICS] . Electrochemical and catalytic study of a trimetallic Cu(II) derivative in DMSO with the presence of trifluoroacetic acid as weak proton source shows the hydrogen evolution Faradaic efficiency as 87%. A continuous increment of the charge accumulation through time is observed, indicating the high stability of our catalyst under electrochemical H2 generation.