Mixed-metal g-C₃N₄ composites for electrocatalytic water splitting and peripheral degradation applications

This work presents a novel Mn/Sr mixed-metal graphitic carbon nitride (g-C₃N₄) composite synthesized via a combined impregnation and calcination approach. This study investigates the possibilities of a Mn/Sr-incorporated g-C₃N₄ composite functioning as a bifunctional material for water splitting electrocatalysis and photocatalytic environmental remediation applications. The electrocatalytic performance of the as-prepared material was evaluated for water splitting in an alkaline medium (1.0 M KOH), where it delivers overpotentials of 360 mV for the oxygen evolution reaction (OER) and 236 mV for the hydrogen evolution reaction (HER), demonstrating its bifunctional catalytic capability. Although the catalytic performance remains moderate compared with state-of-the-art systems, the present study establishes the feasibility of incorporating Mn and Sr into the g-C₃N₄ framework to induce synergistic effects and generate active sites for dual applications. In addition to electrochemical activity, the composite was assessed for peripheral degradation applications, achieving ∼95% degradation of methylthioninium chloride within 90 minutes under light irradiation, confirming its functional responsiveness toward pollutant degradation. The photocatalytic investigation is presented as a preliminary evaluation to support the functional activity of the composite towards pollutant degradation. Further improvements through compositional optimization, defect engineering, and mechanistic understanding are expected to enhance the overall efficiency of this emerging material system.