This mini-review discusses doping and heterojunction formation in ZnO-based catalysts for catalytic applications. Doping introduces new energy levels that enhance charge transfer and light absorption, while heterojunctions improve charge separation and reduce electron-hole recombination. ZnO, with its high redox potential and stability, is a promising catalyst but faces challenges in visible light absorption and electron-hole recombination. Doping and heterojunctions help overcome these issues by modifying ZnO's properties. Doping creates mid-gap energy levels, facilitating charge transfer between semiconductors. Heterojunctions, formed by different band gap materials, enhance charge transfer mechanisms. Techniques like XRD, PL, DRS-UV-vis, XPS, and STEM are used to analyze these effects. Doped ZnO shows reduced PL intensity, indicating lower electron-hole recombination. The Mott-Schottky plot helps determine the band edges and type of semiconductor. Doping with transition metals like Mn, Co, Cu, Ag, and Fe creates mid-gap energy levels and affects optical and magnetic properties. For example, Mn doping increases oxygen vacancies and ferromagnetic properties, while Co doping enhances visible light absorption and magnetic properties. Heterojunctions, such as Z-scheme and staggered-type, improve charge separation and photocatalytic efficiency. The Z-scheme mechanism involves electron transfer between two semiconductors, while the staggered-type involves band alignment. Noble metals like Ag and Au can act as charge mediators, enhancing visible light absorption and reducing recombination. The review highlights the importance of doping and heterojunctions in improving ZnO-based catalysts for efficient catalytic applications.This mini-review discusses doping and heterojunction formation in ZnO-based catalysts for catalytic applications. Doping introduces new energy levels that enhance charge transfer and light absorption, while heterojunctions improve charge separation and reduce electron-hole recombination. ZnO, with its high redox potential and stability, is a promising catalyst but faces challenges in visible light absorption and electron-hole recombination. Doping and heterojunctions help overcome these issues by modifying ZnO's properties. Doping creates mid-gap energy levels, facilitating charge transfer between semiconductors. Heterojunctions, formed by different band gap materials, enhance charge transfer mechanisms. Techniques like XRD, PL, DRS-UV-vis, XPS, and STEM are used to analyze these effects. Doped ZnO shows reduced PL intensity, indicating lower electron-hole recombination. The Mott-Schottky plot helps determine the band edges and type of semiconductor. Doping with transition metals like Mn, Co, Cu, Ag, and Fe creates mid-gap energy levels and affects optical and magnetic properties. For example, Mn doping increases oxygen vacancies and ferromagnetic properties, while Co doping enhances visible light absorption and magnetic properties. Heterojunctions, such as Z-scheme and staggered-type, improve charge separation and photocatalytic efficiency. The Z-scheme mechanism involves electron transfer between two semiconductors, while the staggered-type involves band alignment. Noble metals like Ag and Au can act as charge mediators, enhancing visible light absorption and reducing recombination. The review highlights the importance of doping and heterojunctions in improving ZnO-based catalysts for efficient catalytic applications.