Facile room temperature synthesis of CoSn(OH)₆/g-C₃N₄ nanocomposite for oxygen evolution reaction

Abstract

The development of low cost and earth abundant efficient electrocatalysts is one of the effective strategies to enhance the oxygen evolution reaction (OER) activity. Herein, a facile strategy is demonstrated to synthesize OER active CoSn(OH)₆/g-C₃N₄ (CS/gCN) nanocomposite at room temperature. Among the prepared composites of different compositions, CS/gCN100 composite with ∼37wt% gCN as confirmed by thermo gravimetric analysis exhibits a good OER activity with an overpotential of 336 mV at 10 mA cm⁻² and a Tafel slope of 50 mV dec⁻¹ in 1 M KOH electrolyte, which is better than the commercial available standard IrO₂. The improved OER activity of CS/gCN100 of similar materials is ascribed to high specific surface area (107 m² g⁻¹), high electrochemical active surface area (4.55 cm²) and low charge transfer resistance (6.26 Ω) due to the synergistic effect of g-C₃N₄ and OER active CoSn(OH)₆. The OER activity of CS/gCN100 is further demonstrated by fabricating a two-electrode system with Pt/C as hydrogen evolution electrocatalyst for water splitting in an alkaline medium. The two-electrode system delivers an overall voltage of 1.66 V to achieve 10 mA cm⁻² with excellent durability for water splitting application.