As one of the most promising photocatalysts, TiO 2 suffers from disadvantages of a wide band gap energy and especially the ultrafast recombination of photoinduced-charges, which limit its practical application for efficient solar water splitting. Here we show a hitherto unreported carbon/TiO 2 /carbon nanotube (CTCNT) composite featuring a TiO 2 nanotube sandwiched between two thin tubes of carbon with graphitic characteristics. The carbon layer is only about 1 nm thick covering the surface of TiO 2 nanotubes. The minimum bandgap between the edges of band tails for the CTCNTs can conjecturally be narrowed to 0.88 eV, and the measured apparent quantum efficiency of CTCNT in the ultraviolet light region is even close to 100%, indicating it can greatly enhance the utilization of sunlight and extremely suppress charge recombination. As a consequence, under illumination of one AM 1.5G sunlight, CTCNT can give a superhigh solar-driven hydrogen production rate (37.6 mmol h À1 g À1 ), which is much greater than the best yields ever reported for TiO 2 -based photocatalysts. We anticipate this work may open up new insights into the architectural design of nanostructured photocatalysts for effective capture and conversion of sunlight. Broader contextSolar-driven water-splitting into H 2 and O 2 is recognized as a promising clean, sustainable way to overcome the limited supply of fossil fuels and the greenhouse effect. This requires that photocatalysts effectively harvest sunlight and simultaneously drive the photoreaction with high quantum efficiency. The rational design of efficient catalysts for water splitting is one of the major challenges in recent years. In this work, we show a hitherto unreported carbon/TiO 2 /carbon nanotube structure (CTCNT) that features in a TiO 2 nanotube sandwiched between two thin tubes of graphitic carbon. This unique construction endows the CTCNT material with a minimum bandgap narrowing to 0.88 eV and an excellent apparent quantum efficiency of nearly 100% in the ultraviolet light region. As the result, a super-high solar-driven hydrogen production rate (37.6 mmol h À1 g À1 ) can be given by the CTCNT material, indicating it can greatly enhance the utilization of sunlight and extremely suppress the charge recombination. We anticipate this work may open up new insights to improve the photocatalytic conversion efficiency in solar-driven reactions.

Photocatalytic water splitting for H2 evolution is appealing for transforming solar energy into clean chemical fuel. This technique generally requires noble metals as H2 evolution cocatalysts to facilitate efficient cleavage of water. Herein, we report a noble-metal-free TiO2 nanobelts composite photocatalyst, in which TiO2 nanobelts are supported by nitrogen-doped graphene coordinated with a single Co atom (Co-NG). The results show that Co-NG is an efficient cocatalytst for the photocatalytic H2 production over TiO2. The optimal amount of Co-NG loading is found to be 3.5 wt %, showing a H2 evolution rate of 677.44 μmol h–1 g–1 under illumination of AM 1.5 G simulated sunlight, which is close to that of platinized TiO2 nanobelts and 2.6 and 31.2 times greater than that of 3.5 wt % NG/TiO2 nanobelts composite and pure TiO2 nanobelts, respectively. The significantly improved photocatalytic activity is ascribed to the remarkable synergistic effect between single-atom Co and N-doped graphene, which serve as effective H+ reduction sites and efficient electron acceptors, respectively. Besides, the Co-NG cocatalyst also effectively retards the recombination of photoinduced charge carriers and leads to a prolonged lifetime of charge pairs. This study reveals that Co-NG is an up-and-coming candidate as cocatalyst for development of cost-effective photocatalysts for efficient solar-driven H2 evolution.

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ABSTRACT:A new type of inorganic-polymer hybrid materials of epoxy/silica-titania had been prepared by incorporating grafted epoxy, which had been synthesized by epoxy and tetraethoxysilane (TEOS), with highly reactive TEOS and tetrabutyltitanate (TBT) by using the in situ solgel process. The grafted epoxy was confirmed by Fourier transform infrared spectroscopy (FT-IR) and 1 H-NMR spectroscopic technique. Results of FT-IR spectroscopy and atomic force microscopy (AFM) demonstrated that epoxy chains have been covalently bonded to the surface of the SiO 2 -TiO 2 particles. The particles size of SiO 2 -TiO 2 are about 20 -50 nm, as characterized by AFM. The experimental results showed that the glass-transition temperatures and the modulus of the modified systems were higher than that of the unmodified system, and the impact strength was enhanced by two to three times compared with that of the neat epoxy. The morphological structure of impact fracture surface and the surface of the hybrid materials were observed by scanning electron microscopy and AFM, respectively.

Li-rich material 0.4Li2MnO3·0.6LiNi1/3Co1/3Mn1/3O2 with a layered/spinel heterostructure is synthesized by a simple strategy. On the basis of structure and morphology analyses, it is revealed that the as-prepared Li-rich material possesses both porous micronano structure and integral layered-spinel heterostructure. Moreover, the obtained layered-spinel cathode material possesses prominent electrochemical characteristics, especially its rate capability. The initial discharge capacity of the as-prepared material is 269 mAh g–1 with a high Coulombic efficiency of 90.3%. The material delivers discharge capacities of 239 mAh g–1 at 0.5C, 195 mAh g–1 at 5C, and 175.8 mAh g–1 even at 10C. Also, the capacity retention of the cell is still as high as 80% at high current density (5C) after 200 cycles. The addition of spinel can inhibit the collapse of the material structure and voltage fading upon cycling. The 3D spinel Li4Mn5O12 phase in the Li-rich compound could provide a fast Li-ion diffusion pathway and a porous micronano structure which are key parameters for the remarkable excellent electrochemical performance of the as-prepared cathode material.