Sn_0.94Bi_0.03X_0.03O₂ (X = Cu, Zn) semiconductor compositions: enhanced physical, optical, electrical, dielectric, and photocatalytic properties for the elimination of organic contaminants

In this study, SnO₂ semiconductors codoped with both (Bi, Cu) and (Bi, Zn) were synthesized using the simple, easy and facile coprecipitation technique. The resulting samples exhibited high efficiency as visible light photocatalysis, enabling the effective elimination of various organic contaminants. The X-ray diffraction (XRD) analysis of all samples proved the formation of a tetragonal SnO₂ structure with a mean crystallite size of 17–23 nm. Based on scanning electron microscope (SEM) images, extremely fine spherical particles were seen for pure, (Bi, Cu), and (Bi, Zn) codoped SnO₂ powders. The energy dispersive X-ray (EDX) elemental mapping of (Bi, Cu) codoped SnO₂ powder confirmed the uniform spatial distribution of Bi and Cu dopants. The band gap energy of pure SnO₂ powder was found to be 3.45 eV. For (Bi, Cu) and (Bi, Zn) codoped SnO₂ samples, the band gap energy was estimated to be 2.88 and 3.06 eV, respectively. Furthermore, (Bi, Cu) and (Bi, Zn) codoped SnO₂ samples have strong absorption tails that extend to 1.2 eV and 2.6 eV, respectively. The additive of (Bi, Cu) dopants intensely amplified the dielectric constant of the SnO₂ sample principally at low frequencies with a maximum estimated value of 3234 at 50 Hz. The photocatalytic measurements showed that (Bi, Cu) codoped SnO₂ catalyst has a photo-removal efficiency of 97, 93 and 98% for 25 mg/L Congo red, Imidacloprid, and Malachite green after 40 min of visible irradiation. For the Sn_0.94Bi_0.03Cu_0.03O₂ catalyst, the impact of adsorption and photocatalysis leads to strong de-pollution properties.