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

A trinuclear copper(II) complex, namely [Cu3(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 H2 production from charge aggregation during electrolysis to the practical amount of H2 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 H2 evolution obtained using a Cu(II) derivative (CuII 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: [Figure not available: see fulltext.]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.