Defect enriched luminescent MXene-derived TiO2 for supercapacitors

Abstract

To utilize the intriguing properties of MXene and titania, here in this work, we have synthesized defect-enriched TiO2 by thermal annealing of MXene phase (Mxene-derived-TiO2) and characterized using X-ray diffraction, Raman spectroscopy, Field emission, and transmission electron microscopy. Such uniquely derived MXenederived-TiO2 displayed bright blue light photoluminescence (PL) under near UV excitation. The electrochemical analysis underscores the superior electrochemical performance of MXene-derived-TiO2, particularly in terms of specific capacitance and pseudocapacitive behavior, making them highly suitable for supercapacitors. The oxygen and titanium vacancies present in MXene-derived-TiO2 are responsible for its excellent PL and supercapacitor action. Such defect-induced origin of PL and supercapacitive action is further validated by the addition of NiO. Electron paramagnetic resonance (EPR) and positron annihilation lifetime spectroscopy (PALS) suggested addition of NiO to Mxene-derived-TiO2 leads to a reduction in defect density of titanium vacancies and is reflected in the lowering of PL intensity and resulted in inferior supercapacitive properties.