An efficient poly(5-(4-methoxyphenyl)dipyrromethane based Mn(II) complex modified glassy carbon electrode for photo-assisted electrocatalytic water oxidation at neutral pH

Abstract

Development of efficient, robust, stable, and inexpensive catalyst for water oxidation is one of the most challenging tasks for the scientific community. To increase the durability and long term stability of molecular water oxidation catalyst, heterogenization of molecular catalyst on the electrode surface has emerged as a promising approach. In this pursuit, here we report the electro-polymerization of 5-(4-methoxyphenyl)dipyrromethane(mdp) and subsequently formation of polymeric manganese (II) complex through self-assembly on a glassy carbon electrode for electrochemical and photo-electrochemical oxidation of water. The modified electrode was characterized by using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, UV-visible spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray(EDX) analysis, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The newly developed electrode Mn-mdp-GCE, can electrocatalyze water oxidation in the presence of white LED light more efficiently (Faraday efficiency ∼ 83 %) in neutral pH medium. The Mn(II) polymeric complex modified electrode can photoelectrocatalyze water oxidation at low overpotential (η) =306 mV at J = 1.0 mAcm-2.The surface immobilized polymeric Mn(II) complex shows high stability during seven hours long electrolysis and was confirmed its molecular identity from voltammetric, spectroscopic and microscopic results.