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Recently, various kinds of methods have been implemented to broaden the visible light response and fasten the carrier's separation of TiO2‐based photoanodes. As a promising hydrogen evolution reaction catalyst, MoSe2 is rarely investigated especially combined with TiO2 photoanode. In this study, we report a composite photoanode of MoSe2 nanosheets (with 1T and 2H phase)‐modified 3D TiO2 nanoflowers (NFs).The hybrid of 3D TiO2 NFs/2D MoSe2 holds great promise in boosting the PEC water splitting performance. TiO2 NFs/MoSe2‐15 showed the largest photocurrent density of 1.40 mA/cm2, which was five times higher than that of pure TiO2 NFs under AM1.5G illumination. Moreover 10 times improvement in current density was observed for the TiO2 NFs/MoSe2‐15 under visible light. This increase could be ascribed to synergistic effects of light absorption enhancement and more efficient carrier separation after MoSe2 modification. This study not only provides a reference to boost the photoelectrochemical performance of photoelectrodes but also renders a perspective on the potential applications of MoSe2 nanosheets. [ABSTRACT FROM AUTHOR]

ZnS has been found superiority in photoelectrochemistry for the fast response of photo‐inducing and its high conductor band position (~0.8 eV) results in strong reduction ability for hydrogen production. However, the solar absorbance of ZnS is much low for the wide band gap (~3.2 eV) and the carriers' migration efficiency also need to be improved. Here, nano‐ZnS were coupled with ultrathin SnS2 nanosheets as heterojunction composites. This heterojunction composite demonstrated largely increase in specific surface area (from 4 to 12‐25 m2/g), obvious improvement of UV‐vis absorbance and narrower band gap. Furthermore, the carriers' migration efficiency of ZnS/SnS2 heterojunction has been confirmed to be much higher by photocurrent response and electrochemical impedance spectroscopy. Due to the improvement in structure, compared with pristine ZnS, this ZnS/SnS2 heterojunction exhibited vast enhancement in photoelectrochemical performance. The composite with best activity exhibited 12.8 times enhancement in photocurrent density. The conduction band and valence band of ZnS are both more negative than those of SnS2, the photo‐induced electrons at the conduction band of ZnS will transfer into the conduction band of SnS2 while the photo‐induced holes at the valence band of SnS2 will transfer into the valence band of ZnS. In this way, the photo‐produced carriers will flow into different semiconductors and the carriers' migration efficiency is enhanced. The work improves a new structure to develop the heterojunction property for photoelectrochemical application. High carriers transmission efficiency ZnS/SnS2 heterojunction was obtained which exhibited excellent photoelectrochemical activity. [ABSTRACT FROM AUTHOR]

Abstract: As an efficient cocatalyst, the 2D MoS2 is thought to be a promising substitute to noble metals in the hydrogen evolution reaction (HER). In the past few years, single and few‐layer MoS2 nanosheets have attracted a wide range of concerns for HERs. In this paper, single crystalline ZnO nanowires and MoS2 nanosheets are fabricated to form MoS2 nanosheet/ZnO nanowire hybrid nanostructure to enhance the hydrogen photogeneration. The results show that the hybridization of ZnO with moderate MoS2 loading could enhance the PEC activity by producing more electrons and holes and reducing their recombination. The synthesis of MoS2/ZnO composites proposed an effective way to build low cost and highly active HER catalysts. Moreover, the study on MoS2/ZnO composites sheds light to the deep insight into the mechanism of photoelectrocatalytic HERs. [ABSTRACT FROM AUTHOR]

This work prepared an anatase TiO2 by controlling coexposed {101} and {001} facets. The anatase TiO2 was composited with MoS2, and the photocatalytic behavior was studied. The relationship between the exposed ratio of {001} facets and the enhancement proportion by the composite was compared. An appropriate exposed ratio of {001} facets, instead of a high ratio, can cause the highest enhancement proportion for photocatalytic activity. This finding confirmed that exposed {001} facets are not the main factors for improving photocatalytic activity. Dual heterojunction was observed to form between MoS2 and anatase TiO2 with coexposed {101} and {001} facets, which is a crystal-face heterojunction between {101} and {001} facets and a semiconductor heterojunction between MoS2 and {001} facets of TiO2. In this dual heterojunction, photo-induced electrons in TiO2 will flow into {101} facets of TiO2, instead of MoS2, whereas the photo-induced holes in TiO2 will flow into MoS2 to reach a high separation efficiency. This finding further revealed the elevating mechanism of constructing heterojunction based on coexposed crystal faces. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a novel approach to control the photocatalytic selectivity of TiO2 though different dominant crystal facets. {101}, {111}, and {001} facets exposed nanoscale anatase TiO2 were obtained by a simple hydrothermal route with different ratio of NH4+ and F−, then a calcined progress to clear surface adsorbent atoms. Results reveal that {101} exposed TiO2 has some remain binding N with a mode of unsaturated N3c exhibits selectively photocatalytic degradation of methylene orange ( MO) in a methylene blue ( MB) and methyl orange ( MO) mixed solution, whereas TiO2 with exposed {111} and {001} facets exhibits photocatalytic selectivity for MB. The {111} facets of anatase TiO2 exhibit a better photocatalytic selective ability than {001} facets. It confirms that the photocatalytic selectivity can be affected by different dominant crystal facets. In a deeper analysis, there are many unsaturated O2c on the surface of {001} and {111} facets, which enhances adsorbent selectivity and relevant photocatalytic activity of MB, at the same time, the unsaturated O2c on the surface of {111} facets is much more than that on the surface of {001} facets results in a better photocatalytic selectivity of {111} facets. This research hopes that developing a new strategy for photocatalytic selectivity and providing a deeper understanding of different crystal facets of TiO2. [ABSTRACT FROM AUTHOR]

Alkaline-earth metal Ca and N codoped TiO2 sheets with exposed {001} facets were obtained through a one-step hydrothermal process. The codoped TiO2 appears as microsheets with length of 1-2 μm and thickness of 100-200 nm. The X-ray diffractometer and X-ray photoelectron spectroscopy results confirm that Ca and N codoped TiO2 has higher crystallinity than N-doped TiO2, as well Ca, N atoms were successfully codoped into TiO2 as interstitial Ca and interstitial N or an O-Ti-N structure, respectively. Compared with N monodoped, further alkaline-earth Ca codoped has little influence on the energy bands of TiO2 except slightly elevating the conduction band edge at a value of 0.02 eV. The hydroxyl radicals (•OH) producing and photocatalytic experiment shows that Ca and N codoped can effectively decrease the generation of recombination centers, and enhance separation efficiency of photo-induced electrons and holes as well as the photocatalytic activity of TiO2. The codoped photocatalyst has the highest photocatalytic activity when Ca doped ratio reach 0.48%. Excess Ca doped will weaken the crystallization of anatase TiO2, form charge center, produce new recombination centers and finally reduce the photocatalytic activity of TiO2. [ABSTRACT FROM AUTHOR]