Bi-metallic zeolitic imidazolate framework (ZIF) derived ZnO/Co₃O₄ heterostructure: effect of calcination temperature on microstructural and photocatalytic properties

Zeolitic imidazolate framework (ZIF) derived semiconductor metal oxides have piqued researchers' interest as they are highly sought-after materials in photocatalysis. However, the photocatalytic efficacy of these materials heavily relies on some critical factors like specific surface area, phase composition, and microstructure. In view of this, the present study seeks to establish a correlation between calcination temperature and the photocatalytic response of ZIF-derived metal oxides. Bi-metallic Zn/Co-ZIF had been thermally treated at varying temperatures (500 °C, 600 °C, and 700 °C) to fabricate ZnO/Co₃O₄ composites. The XRD studies and BET analysis revealed an increase in crystallite size and reduction in surface area of the composites owing to inter-agglomerate sintering of nanoparticles. The photocatalytic performance of the derived materials was then comparatively evaluated against the degradation of the tetracycline (TC) antibiotic. Zn/Co-ZIF calcined at 600 °C exhibited maximum degradation efficiency compared to the rest of the composites on account of suitable crystallite size, enhanced surface area along with expanded pore volume and pore diameter, and enhanced photo-induced charge carrier separation.