Novel S-scheme based nanocomposite of MXene/V2O5 for environmental remediation towards sustainable development: An insight into influencing parameters.

Abstract

In this study, a novel 2D/2D nanocomposite of MXene and V₂O₅ was synthesized using a facile hydrothermal approach for the efficient removal of crystal violet (CV), a textile dye from contaminated water to achieve Sustainable Development Goal (SDG) 14; "Save Lives Below Water". Here, the catalytic performance of pristine MXene was prominently boosted with the introduction of ball milled V₂O₅ as an electron generating agent. The degradation efficiency of synthesized nanocomposite significantly enhanced from 57 % to 92 %, 41 % - 76 % and 7 % - 58 % with an error of ±2 % as compared to pristine MXene at 10, 20 and 30 ppm concentrations of CV, respectively. The effective degradation of pollutants is ascribed to the electron-transfer via S-scheme based mechanism and helps in reducing recombination rate of photogenerated carriers, which could produce hydroxyl radicals (OH^.) as a primary species for effectively degradation of pollutants. The superior performance of nanocomposite is attributed to: (i) the optimized surface charge (-27.8 mV), (ii) small value of charge transfer resistance (R_ct = 1.3 Ω), (iii) enhanced value of carrier concentration (6.3 X 10³² cm^-3), (iv) small recombination rate of excitons and (v) high specific surface area as compared to pristine samples. Moreover, to strengthen the findings, scavenger study and electron paramagnetic resonance (EPR) study were carried out and concluded that hydroxyl radicals (OH^.) are the primary species in the mineralization of CV dye. The values of lande g-factor are calculated using EPR plots which comes out to be 2.03 and 2.04 for (O₂^.-) and (OH^.) radicals, respectively and demonstrates the formation of free radicals during catalytic reactions. The Chemical Oxygen Demand (COD) analysis was carried out before and after the removal of CV using MV nanocomposite and confirms the reduction in COD vlaue of 81.60 %. The reusability experiment confirms stability of synthesized sample and provides a good shred for industrial applications in the treatment of wastewater and getting out cleaner productions and to save marine ecosystem.