Electrocatalytic hydrogen evolution at carbon paste electrodes doped with a manganese(II) imidazoledicarboxylate complex

Abstract

Abstract A mononuclear Mn(II) complex [Mn( p -MOPhH 2 IDC) 2 (H 2 O) 2 ]·2(DMF), was synthesized by the reaction of p -MOPhH 3 IDC (2-(4-methoxyphenyl)-1 H -imidazole-4,5-dicarboxylic acid) and Mn(CH 3 COO) 2 ·4H 2 O under solvothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis, IR and UV–vis spectroscopy. The structure analysis revealed that the manganese(II) center has a six-coordinated octahedral coordination geometry. The performance of a Mn(II) complex-doped carbon paste electrode (Mn-CPE) in the electrocatalytic hydrogen evolution reaction (HER) was evaluated by linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) methods. The polarization curve shows that the η 10 298K (overpotential, 10 mA cm −2 ) of the Mn-CPE was positively shifted by 341 mV compared with the bare CPE (without complex). The Tafel slope of the Mn-CPE was 161 mV dec −1 . These data indicate that the Mn-CPE was effective in the HER electrocatalytic reaction. For EIS experiments, the arc diameter of the high-frequency region of the Mn-CPE was much smaller than that of the bare CPE, which further indicates the effective catalytic capacity of the Mn(II) complex for hydrogen evolution. The information obtained from this study will help to expand the application of Mn(II) complexes in the field of electrochemistry.