Bio-based synthesis of oxygen-deficient Ni-doped TiO2 using waste pineapple peel: Density functional theory studies and photocatalytic degradation of furazolidone

Pharmaceutical wastewater poses a significant environmental threat due to its toxicity and microbial resistance to conventional treatment methods. This study introduces a novel, eco-friendly approach for synthesizing Ni-doped TiO 2 using waste pineapple peel extract for enhanced degradation of furazolidone (FZD). The primary objective is to investigate the impact of bio-based Ni doping on structural, electronic, and photocatalytic properties, mainly focusing on oxygen vacancies (OVs), Ti 3+ defects, and enhanced surface hydrophilicity . Bio-based Ni-doping results in a reduced bandgap (from 3.29 to 2.54 eV), delayed recombination and hydrophilic surface (water contact angle: 120.8°→52.9°) using Ni 4.80 /TiO 2 (bio) (4.8 % w/w Ni-doped). Ni 4.80 /TiO 2 (bio) showed ∼ 11.65 times higher photocurrent density than Ni 0.00 /TiO 2 (bare). Density functional theory (DFT) calculations incorporating the Hubbard parameter (U) investigated emergence of new energy levels, corresponding to Ni incorporation, OVs, and Ti 3+ defects in Ni-doped TiO 2 , validating the experimental findings. Ni 4.80 /TiO 2 (bio) exhibited a superior 90.44 ± 2.73 % FZD (5 mg L −1 ) degradation over Ni 0.00 /TiO 2 (bare) and chemically synthesized Ni-doped TiO 2 (Ni 4.80 /TiO 2 (chem)), which showed a degradation of 62.45 ± 2.85 and 73.41 ± 2.79 %, respectively, under visible light . Ni 4.80 /TiO 2 (bio) showed the highest quantum yield (QY) of 22.27 ± 0.41 % at the optimized pH 3. Ni 4.80 /TiO 2 (bio) achieved ∼ 72.8 % FZD degradation during 4 th cycle of its reuse. FZD underwent degradation through formation of 17 intermediates in three different pathways. Overall, this work provides a new direction for bio-based semiconductor design in environmental applications. • Nature-inspired Ni-doping onto TiO 2 to increase oxygen vacancies and Ti 3+ defects. • Density of state infers upper VB and lower CB potential mostly of O and Ti interactions. • DFT calculated bandgap well matches with UV-DRS and VB-XPS results. • Ni/TiO 2 achieves furazolidone degradation of 90.4 % with 22.3 % quantum yield. • Furazolidone degraded in three pathways with formation of 17 intermediates.