The development of SnO2 quantum dots (QD) on metal–organic framework-5 (SnO2/MOF-5): Characterization, feasibility and pathways in photocatalytic degradation of Eriochrome Black t

This study synthesizes a nanocomposite of nanosized Stannic oxide particles (SnO₂) decorated on [Zn₄O (BDC)₃] metal–organic framework-5 (SnO₂/MOF-5) using a facile solvent-thermal precipitation technique. This nanocomposite has outstanding catalytic degradation capabilities for Eriochrome Black T (EBT). TG-DTG, XRD, BET, BJH, FE-SEM, FT-IR, UV–VIS DRS, PL, and EDX techniques characterized the as-synthesized samples. Based on Scherrer and Williamson-Hall methods, the average crystallite size of the nano-composite samples was 43.3 nm and 65.0 nm, respectively. As a result of pHpzc measurements on SnO₂ and SnO₂(30 %wt)/MOF-5 samples, the pHpzc values of these samples were approximately 7.7 and 7.8, respectively. Our experiments showed that MOF-5, SnO₂, and SnO₂(30 %wt)/MOF-5 samples exhibit absorption edges of 328, 456, and 350 nm, respectively, associated with bandgap energies of 3.78, 2.71, and 3.54 eV, respectively. Based on the experimental parameters, it has been confirmed that 10 mg/L EBT can be degraded perfectly at these optimum operational parameters: SnO₂(30 %wt)/MOF-5: 1 g/L, pH: 5.0. In comparison with other binary photocatalysts, SnO₂(30 %wt)/MOF-5 showed the most impressive photocatalytic performance. The combination of the wide bandgap n-type SnO₂ semiconductor, having a high electron mobility, with MOF-5′s high surface area (up to 3000 m2/g) and ordered porosity improves the reaction kinetics. The high chemical and mechanical stability of incorporated SnO₂ forms a protective interface, mitigating MOF-5′s degradation in aqueous or harsh environments. For the best-boosting effect, the binary catalyst’s SnO₂/MOF-5 mass ratio must be 30 %wt (optimum: 30 %wt). Observations revealed that the photodegradation kinetics followed the Hinshelwood model (k = 0.011 min⁻¹, t_1/2 = 58.72 min). As a result of COD analysis on photodegraded EBT solutions, a Hinshelwood plot was obtained with a slope of 0.025 min⁻¹ (t_1/2 = 27.72 min). Despite four consecutive reaction cycles, there was no noticeable sign of performance decay after using SnO₂ (30 wt%)/MOF-5 for reusability.