ZIF‐67‐Templated Polyhedral Co ₃ O ₄ via Facile Thermal Air Oxidation for Efficient Hydrogen Generation From NaBH ₄

ABSTRACT

This study addresses the slow self‐hydrolysis (uncatalyzed hydrolysis) of sodium borohydride (NaBH ₄ ) by developing ZIF‐67@400 catalysts. Pristine ZIF‐67 was synthesized at room temperature and subsequently calcined in air at temperatures ranging from 200°C to 500°C. Among the as‐synthesized and thermally treated samples, the catalyst calcined at 400°C (ZIF‐67@400) exhibited the highest performance, a hydrogen generation rate (HGR) of approximately 1,212 mL min ^.‐1 g ⁻¹ under a catalyst loading of 10 mg with 52.87 mM NaBH ₄ at room temperature. Under optimized conditions ZIF‐67@400, 20 mg of ZIF‐67@400 loading, 264 mM NaBH ₄ and a reaction temperature of 313 K (40°C), the HGR increased to 9,516 mL min ⁻¹ g ⁻¹ . The activation energy ( E _a ) was calculated to be 65.76 kJ mol ⁻¹ , which is consistent with values reported in the literature. These findings demonstrate that precise thermal treatment of MOF precursors can substantially enhance catalytic performance, offering an efficient strategy for hydrogen generation.