Enhancing Photocatalytic Efficiency through Morphology and Bandgap Tuning in Gallium‐Doped Zinc Oxide Nanoparticles

The photocatalytic degradation of organic dyes in a low‐energy 3D‐printed photoreactor (20 mWh day −1 ) is investigated using nanoparticles synthesized via spray‐assisted co‐precipitation. The study investigates nanoparticles with pseudohexagonal and elongated spindle‐like morphologies, doped with varying gallium levels (0.5–20 mol%), providing new insights into dopant‐induced effects on photocatalytic performance. Structural characterization via X‐ray powder diffraction and Fourier transform infrared confirms dopant incorporation. Gallium doping systematically reduces the optical bandgap energy (), enhancing charge separation and photocatalytic efficiency. The undoped pseudohexagonal and elongated spindle‐like nanoparticles exhibit bandgap energies of 3.183 and 3.192 eV, respectively, which decreased to 3.146 and 3.171 eV with increasing doping levels. Brunauer‐Emmett‐Teller analysis shows that pseudohexagonal nanoparticles have a larger surface area (9.46 m 2 g −1 ) than spindle‐like nanoparticles (5.09 m 2 g −1 ). Despite this, spindle‐like nanoparticles generally exhibit higher photodegradation efficiencies than pseudohexagonal nanoparticles, reaching 94.32% for Phloxine B over 24 h, with similar trends observed for Oxazine 170 and Rhodamine 123. The rate constant systematically increases with gallium content, particularly in spindle‐like ZnO. These findings highlight the importance of nanoparticle morphology and doping in optimizing energy‐efficient photocatalytic materials for sustainable environmental remediation or self‐cleaning surfaces.