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.

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The commercial application of biocatalysts depends on the development of effective methods of immobilization. The immobilization of enzymes greatly increases the stability of enzymes and eases the burden of enzyme cost and thus, is widely pursued for efficient, selective, and environmentally friendly catalysis. This brief perspective focuses on recent development in the area of enzyme immobilization in porous materials. Recent work regarding the immobilization of enzymes in inorganic mesoporous materials as well as the modifications to those materials is summarized in this paper. The configuration of supported enzyme as membranes and fibers may facilitate their application in areas that require a biocatalytic process. Enzymes immobilized in or on fibrous membranes provide high surface area for high throughput biocatalysis. These membrane bioreactors also allow for biotransformations to be carried out within a continuous flow process while maintaining enzyme stability under operating conditions as a result from the enzyme immobilization. A summary of efforts to prepare immobilized enzymes in fibers and electrospun fibers will also be discussed.

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