Hydrogen evolution performance of a Ag(I) bis(benzimidazole) coordination polymer doped carbon paste composite electrode

Abstract

A new Ag(I) coordination polymer, [Ag2(BBO)]n, H2BBO = 1,3-bis(benzimidazol-2-yl)-2-oxopropane, was synthesized by diffusion method and characterized. The structural analysis showed that the Ag(I) coordination polymer has a 2D layered structure, and each polymerization unit is composed of two BBO ligands and four Ag(I) ions, which form two types of structures (border silvers and center silvers). The hydrogen evolution reaction (HER) performance of the composite electrode CE-Ag formed by mixing the Ag(I) coordination polymer and carbon paste electrode was investigated by linear scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The results showed that the overpotential (η10 298) of the obtained CE-Ag was positively shifted by 320 mV when the current density reached 10 mA cm−2 compared with the blank electrode (CE) and the Tafel slope of the CE-Ag was 158 mV dec−1. These indicated that CE-Ag was effective for the HER electrocatalytic reaction. In addition, the smaller charge transfer resistance Rct (40 Ω) of CE-Ag compared with that of CE (2263 Ω) further indicates the effective catalytic capacity of the Ag(I) coordination polymer for hydrogen evolution. The information obtained from this study will help to expand the application of Ag(I) coordination polymers in the field of electrochemistry.