Spinel-type calcium manganese oxide adorned on g-CN composite: A highly proficient electrocatalyst for oxygen evolution reaction (OER)

Abstract

A comprehensive study was performed on water electrolysis to address environmental challenges and energy issues. Eco-friendly and renewable energy systems are required to produce cost-effective electro-catalysts with long-term durability and higher electrocatalytic efficiency to enhance OER. Spinel oxide has recently been used as a promising substitute for transition metal catalysts. They can function as very effective electrocatalysts in water oxidation processes. In current study, the CaMn2O4/g-CN composite was prepared using the hydrothermal technique in 1.0 M KOH in primary media. Distinctive physical and electrochemical analyses evaluated the prepared material's morphology, structure and electrocatalytic components. The composite material showed enhanced electrocatalytic efficacy for OER having a reduced overpotential (η) of 220 mV than pure CaMn2O4 278 mV and possesses a minimal Tafel value (35 mV/dec) contrasted with pristine CaMn2O4 (57 mV/dec). In case of overpotential, the composite material revealed good performance than its pure material while the Tafel slope of CaMn2O4/g-CN exhibited lower value than its individual material (CaMn2O4). Additionally, cyclic stability and chronoamperometric studies measured the electrodes' durability over 30 h. Electrochemical impedance spectroscopy (EIS) investigations indicated that charge transformation at an electrode-electrolyte surface might be feasible with minimal Rct value (0.19 Ω) and it showed excellent improved performance (63 %) better than its pure material, leading it to boost OER properties, attributed to its remarkable electrical conductivity, greater surface area and outstanding stability. These outstanding electrochemical features of the CaMn2O4/g-CN differentiate as an attractive choice for future OER utilization.