In this study, TiO 2 nanotube (TNT)/reduced graphene oxide (hGO) composites were prepared by an alkaline hydrothermal process. This was achieved by decorating graphene oxide (GO) layers with commercially available TiO 2 nanoparticles (P90) followed by hydrothermal synthesis, which converts the TiO 2 nanoparticles to small diameter (∼9 nm) TNTs on the hGO surface. The alkaline medium used to synthesize the TNTs simultaneously converts GO to deoxygenated graphene oxide (hGO). Compared to GO, the hGO has a ∼70% reduction of oxygenated species after alkaline hydrothermal treatment. The graphene nature of hGO in the composites was confirmed by X-ray diffraction (XRD), Raman, FTIR, and X-ray photoelectron spectroscopy (XPS) analysis. The photocatalytic performance of the hGO-TNT composites was evaluated for the photodegradation of malachite green. It was found that the ratio of hGO to TNT in the composites significantly affects the photocatalytic activity. Higher amounts of hGO in hGO-TNT composites showed lower photocatalytic activity than pure TNTs. The composite with 10% hGO showed the highest photocatalytic activity, with a 3-fold enhancement in photocatalytic efficiency over pure TNTs. It is expected that the synthesis of "high surface area-small diameter" TiO 2 nanotubes and simultaneous conversion of GO to graphene like hGO "without using strong reducing agents" could be a promising strategy for preparing other types of carbon based TiO 2 nanotube composite photocatalysts.

Vanadium pentoxide (V2O5) layered nanostructures are known to have very stable crystal structures and high faradaic activity. The low electronic conductivity of V2O5 greatly limits the application of vanadium oxide as electrode materials and requires combining with conducting materials using binders. It is well known that the organic binders can degrade the overall performance of electrode materials and need carefully controlled compositions. In this study, we develop a simple method for preparing freestanding carbon nanotube (CNT)‐V2O5 nanowire (VNW) composite paper electrodes without using binders. Coin cell type (CR2032) supercapacitors are assembled using the nanocomposite paper electrode as the anode and high surface area carbon fiber electrode (Spectracarb 2225) as the cathode. The supercapacitor with CNT‐VNW composite paper electrode exhibits a power density of 5.26 kW Kg−1 and an energy density of 46.3 Wh Kg−1. (Li)VNWs and CNT composite paper electrodes can be fabricated in similar manner and show improved overall performance with a power density of 8.32 kW Kg−1 and an energy density of 65.9 Wh Kg−1. The power and energy density values suggest that such flexible hybrid nanocomposite paper electrodes may be useful for high performance electrochemical supercapacitors.

Yttrium-doped ceria (YDC) nanorods were prepared by hydrothermal synthesis and characterized using Raman, UV−vis, transmission electron microscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The ceria nanorods showed an increase in the amount of oxygen vacancies with an increase in the Y concentration. When the doping level is <30%, the optical band gap of the doped ceria is lower than that of pure ceria nanorods. At < 50% of Y doping, the composite nanorods exhibited a higher photocatalytic activity for the degradation of model organic dyes compared to the pure ceria at room temperature, and the catalyst with 10% loading showed the maximum photocatalytic efficiency. However, at 100 °C, the photocatalytic activity significantly improved for all the nanorods with different Y loadings, and the greatest improvement was obtained for the sample with the highest number of oxygen vacancies.

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