Acquiescent tailoring of TiO2 band gap via surged NiSe NPs decoration for accelerated photocatalytic degradation of methyl orange

Abstract

TiO₂-based photocatalysts are highly active for the degradation of methyl orange in water due to their cost-effectiveness and high efficacy. However, their activity is often limited by factors such as high band gap (3.26 eV), Schottky barrier resistance and rapid electron-hole recombination. To overcome these limitations and enhance catalytic activity, a facile and effective approach is required. In this study, a highly dispersed NiSe-based TiO₂ photocatalyst with a lower band gap and electron-hole recombination was formed using the sol-gel method. The samples were characterized by XRD, Raman spectroscopy, SEM, FTIR, TG-DTG, UV–Vis DRS and elemental mapping. Results revealed that NiSe nanoparticles dispersed smoothly over TiO₂ matrix and effectively reduced the bad gap to 1.5 eV. Experimental results showed that among tested catalysts, 32NiSe/TiO₂ exhibits exceptional performance, achieving a rapid degradation efficiency of 99.2 % in 70 min time due to its remarkable activity rate of 1.33 mmol/h·g, turnover number (TON = 0.51) and turnover frequency (TOF = 0.43 h⁻¹) along with a shorter half-life of 0.176 h. The photodegradation of methyl orange over 32NiSe/TiO₂ predominantly followed pseudo-first-order kinetics with a higher reaction rate of 0.065 min⁻¹. In addition, the exceptional regeneration ability and stability of 32NiSe/TiO₂ make it a suitable and cost-effective candidate for real-world applications.