Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

Highlights: • Bi₂Se₃ and Ni doped Bi₂Se₃ were synthesized by solvothermal approach. • Presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement. • Complete degradation of malachite green (MG) dye was achieved by Ni doped Bi₂Se₃ with H₂O₂. • Remarkable photo-catalytic degradation by doped bismuth selenide has been explained. • Scavenger tests show degradation of MG is mainly dominated by ·OH oxidation process. - Abstract: Bismuth selenide (Bi₂Se₃) and nickel (Ni) doped Bi₂Se₃ were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi₂Se₃. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi₂Se₃ sample exhibited higher photo-catalytic activity than that of the pure Bi₂Se₃ sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi₂Se₃ in presence of hydrogen peroxide (H₂O₂) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.