CuO nanoparticles (NPs), Cu 2 O/CuO and CuO/TiO 2 nanocomposites (NCs) have been synthesized by using modified co-precipitation method with three different schemes of synthesis.Crystal structure and morphology of the samples have been investigated by the synchrotron Xray diffraction and transmission electron microscopy, respectively. The detailed local electronic structure of NPs and NCs has been determined by the X-ray absorption near edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS) spectroscopy. O K-edge, Cu K-and Cu L-edge XANES spectra revealed the dominating +2 valence state of Cu in case of CuO NPs and CuO/TiO 2 NCs, although Cu +1 was dominated in the Cu 2 O/CuO NCs. A comparison of local atomic structure around the Cu sites revealed the shorter Cu -O bond distances in the as-synthesized samples with respect to the bulk CuO or Cu 2 O. The Ti K-edge EXAFS fittings for CuO/TiO 2 NCs revealed that the local anatase TiO 2 phase has been formed, with Ti -O bond distance of 1.98 Å. We further demonstrated that the CuO NPs, Cu 2 O/CuO and CuO/TiO 2 NCs can serve as effective photocatalyst towards the degradation of two novel water 2 pollutants, (i) methyl orange (MO) and (ii) potassium dichromate (PD), under the visible lightirradiation. It was found that the Cu 2 O/CuO NCs exhibit higher photocatalytic activity towards the degradation of MO and PD than the CuO NPs or CuO/TiO 2 NCs. The mechanism of the photodegradation of MO and PD is also discussed in terms of possible chemical reactions, along with the electronic structure and surface properties of the samples.

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The present work explores the electrochemical energy storage performance of Ti3C2T x (MXene) and 1T-VS2 nanosheet hybrids synthesized by a simple in situ hydrothermal method. Different analytical methods such as X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared, Raman spectroscopy, and Brunauer–Emmett–Teller were employed to explore the structural and morphological properties and composition of electrode materials. Furthermore, the electrochemical characterization of 1T-VS2/MXene hybrid electrode materials with different concentrations of MXene was investigated systematically. The all pseudocapacitive asymmetric supercapacitor cell was fabricated by combining the best performing 1T-VS2/MXene and MXene, which displayed the highest specific capacitance of 115.7 F/g at a current density of 0.8 A/g in an expanded potential range of 1.6 V. Additionally, the highest energy density achieved was 41.13 W h kg–1 at a maximum power density of 793.50 W kg–1. The asymmetric supercapacitor was able to achieve a high capacitance retention of 85% and a coulombic efficiency of 100% after 5000 galvanostatic charge–discharge cycles. Moreover, the synergistic effect and charge storage kinetics of the 1T-VS2/MXene hybrid pseudocapacitive electrode material were investigated in detail using experimental and density functional theory calculations. Based on the results, we have further demonstrated the usage of 1T-VS2/MXene and MXene as a high-performance energy storage material for supercapacitor application with the dominating intercalation mechanism. The lower diffusion energy barrier for electrolytic ions in the case of hybrid 1T-VS2/MXene supports the higher charge storage. The enhanced density of states and lower diffusion barrier justify the superior charge storage performance for hybrid 1T-VS2/MXene.

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