Study for the hydrogen evolution reaction of doped carbon paste composite electrodes with multinuclear Ag(I) complexes based on nitrogen heterocyclic ligand

Abstract

Two Ag(I) complexes, [Ag₃(L)₃(BTC)]·3C₂H₅OH (1) [Ag₂(L)₂(TPA)]·2H₂O (2) (L = 1,3-bis[(N-methylbenzimidazole)methylene]-2-aniline, H₃BTC = 1,3,5-benzenetricarboxylic acid, H₂TPA = terephthalic acid ) were synthesized and characterized by elemental analysis, IR, UV-visible spectroscopy and X-ray single crystal diffraction. Structural analysis shows that the two complexes are trinuclear fan-shaped and binuclear central symmetric structures respectively. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were used to study the hydrogen evolution reaction (HER) characteristics of two complexes modified carbon paste electrodes (CE-1 and CE-2) in 0.5M H₂SO₄ electrolyte. The research results indicate that the overpotential (η₁₀^{293 K}) of CE-1 and CE-2 showed a positive shift of 203 and 319 mV compared to CE (without complex, 965 mV), and Tafel slopes (b^{293 K}) are 193 and 175 mV·dec^-1, respectively. The above results manifest that CE-1 and CE-2 have a good electrocatalytic effect on HER and CE-2 is significantly better than CE-1, which is attributed to the greater deformability of the silver(I) ion coordination environment in complex 2. The above conclusions provide a theoretical basis for the application of Ag(I) complexes in the electrochemical field.