Carbon Coated ZnAl ₂ O ₄ Ceramic Composites as Bifunctional Material for Hydrogen Evolution and Supercapacitor Applications

ABSTRACT Water splitting is a promising and sustainable route for hydrogen production, offering a clean energy carrier without carbon‐based emissions. However, its practical implementation relies on efficient, durable, and cost‐effective electrocatalysts. In this study, low‐cost C@ZnAl 2 O 4 nanocomposites were synthesized via a sol–gel method to enhance electrocatalytic and energy storage performance. The structural, morphological, and chemical properties of the materials were systematically characterized using various techniques. HER activity of pristine ZnAl 2 O 4 and carbon‐coated composites was evaluated in 1.0 M KOH using a three‐electrode configuration. Among the studied samples, 60%C@ZnAl 2 O 4 nanocomposite exhibited the best HER performance, delivering an overpotential of −265 mV at 10 mA cm −2 with a Tafel slope of 119 mV/dec, a high electrochemically active surface area (74 cm 2 ), the catalyst also demonstrated good stability during 120 h. The 60%C@ZnAl 2 O 4 electrode showed high supercapacitive behavior, achieving a specific capacitance of 573 F/g at 0.5 A/g. The electrode exhibited high cycling stability, retaining 90% of its capacitance after 3000 charge–discharge cycles in a three‐electrode configuration. The fabricated 60%C@ZnAl 2 O 4 //Carbon asymmetric supercapacitor exhibited a high energy density of 31.67 Wh/kg and retained 87.3% capacitance after 10000 cycles. These results highlight the potential of C@ZnAl 2 O 4 for hydrogen production and energy storage applications.