Controllable synthesis of hollow COFs for boosting photocatalytic hydrogen generation.

COF-LZU1 with a cubic hollow structure was fabricated through a hard template approach by using water solvable NaCl as a template. The precisely prepared COF-LZU1 hollow cube displays an enhanced H2 evolution rate (651 µmol h-1 g-1), which is approximately 1.8 times greater than that of pristine COF-LZU1 (361 µmol h-1 g-1).

Vertical growth of SnS2 nanobelt arrays on CuSbS2 nanosheets for enhanced photocatalytic reduction of CO2.

Two-dimensional SnS2 nanobelt arrays vertically grown on two-dimensional CuSbS2 nanosheet (2D SnS2⊥2D CuSbS2) heterostructures were synthesized via a facile solution-phase growth route. The resultant SnS2⊥CuSbS2 heterostructures showed enhanced photocatalytic activity for CO2 reduction because of unique structural advantages and the p-n heterojunction with matched energy band alignment.

Highly efficient utilization of light and charge separation over a hematite photoanode achieved through a noncontact photonic crystal film for photoelectrochemical water splitting.

The trade-off problem between light absorption and charge collection under lower band-bending (bias) is extremely difficult to resolve in water splitting on photoelectrodes. Although the use of metallic back-reflectors, antireflection coatings, and textured substrates and light absorbers enable the improvement of light utilization efficiency, these methods still suffer from high cost and complex fabrication process, especially, incompetent separation of photogenerated carriers. Here taking the hematite (α-Fe2O3) photoanode as a model, we report that a noncontact photonic crystal (PC) film composed of silica nanoparticles and ethoxylated trimethylolpropane triacrylate (ETPTA) resin can significantly enhance the photoelectrochemical (PEC) activity of the photoelectrode. Specifically, more than 250 mV cathodic shift in the onset potential and 4 times larger photocurrent at 1.0 V versus a reversible hydrogen electrode (RHE) were achieved over the α-Fe2O3-PC photoanode hybrid system, compared with the pristine α-Fe2O3 photoanode. Our work showed that a PC film not only boosted light absorption of the α-Fe2O3 layer but also improved its charge transfer efficiency under light illumination. These new findings of the synergistic effect will open a new avenue to design high-performance solar energy conversion devices.

High-efficient separation of photoinduced carriers on double Z-scheme heterojunction for superior photocatalytic CO2 reduction.

Developing heterojunction is one of promising approaches to acquire desired photocatalysts with high-efficient photocatalytic activity. In this work, sheet-like ternary ZnO/ZnWO4/g-C3N4 composite was synthesized via stepwise calcination treatment. The double interface electric fields built in the ZnO/ZnWO4/g-C3N4 heterojunction can promote efficient separation of photogenerated charge carriers in space. Moreover, in contrast with the individual ZnO, g-C3N4, ZnWO4 and their binary composites, this double Z-scheme heterojunction achieves more light harvesting, larger pore volume, stronger photoreduction capacity and CO2 adsorption capacity. Therefore, the sheet-like ZnO/ZnWO4/g-C3N4 heterojunction exhibits efficient conversion of the CO2 molecules into solar fuels under the light irradiation. The production yield of photocatalytic CO2 reduction over the double Z-scheme heterojunction is 13.19 µmol h-1 g-1 and the conversion rate of hydrocarbon fuel is highly up to 91.5%, which are much higher than that of other samples. This work offers a novel perspective to achieve high-efficiency heterojunction system for photoredox applications such as photocatalytic antibacterial, nitrogen fixation and degradation of pollutions.

Enhanced visible-light photocatalytic H2-generation activity of carbon/g-C3N4 nanocomposites prepared by two-step thermal treatment.

Photocatalytic hydrogen (H2) production from water by using solar energy and a photocatalyst is a green and sustainable route to tackle the energy issues. Herein, carbon/g-C3N4 nanocomposites were successfully synthesized via a two-step thermal treatment of urea and glucose with different ratios. As confirmed by X-ray photoelectron spectroscopy, a C-O-C bond was formed between carbon and g-C3N4, which leads to a strong interaction between carbon and g-C3N4. The prepared samples were evaluated for photocatalytic H2 generation under visible light irradiation. The experimental results indicate that the carbon/g-C3N4 nanocomposites show great photocatalytic H2 evolution activity, as high as 410.1 µmol g-1 h-1, which is 13.6-fold of pure g-C3N4. The enhanced photocatalytic performance not only originates from the enlarged surface area and extended visible light response range, but also from the effectively separated photo-generated charge carriers. This spatial charge separation greatly suppresses the recombination of photo-generated hole-electron pairs and facilitates efficient H2 production. This work provides a facile way to design highly efficient carbon nitride-based photocatalysts for potential application in photocatalytic reaction by using solar energy.

Cubic anatase TiO2 nanocrystals with enhanced photocatalytic CO2 reduction activity.

Single-crystalline anatase TiO2 nanocubes with exposed {100} and {001} facets, prepared by hydrothermal and calcination methods, display especially high photocatalytic activity toward CO2 reduction to methane and methanol, due to the synergistic effects of better crystallization, a more negative conduction band position and co-exposed {100} and {001} facets.

Efficient removal of formaldehyde by nanosized gold on well-defined CeO2 nanorods at room temperature.

Gold (Au) nanoparticles (NPs) supported on well-defined ceria (CeO2) nanorods with exposed {110} and {100} facets were prepared by a deposition-precipitation method and characterized by powder X-ray diffraction, micro-Raman spectroscopy, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption, transmission electron microscopy, high-resolution transmission electron microscopy, and high-angle annular dark-field scanning transmission electron microscopy. Both nanometer and subnanometer gold particles were found to coexist on ceria supports with various Au contents (0.01-5.4 wt %). The catalytic performance of Au/CeO2 catalysts was examined for formaldehyde (HCHO) oxidation into CO2 and H2O at room temperature and shown to be Au content dependent, with 1.8 wt % Au/CeO2 displaying the best performance. On the basis of the results from hydrogen temperature-programmed reduction and in situ Fourier transform infrared spectroscopy observations, the high reactivity and stability of Au/CeO2 catalysts is mainly attributed to the well-defined ceria nanorods with {110} and {100} facets which present a relatively low energy for oxygen vacancy formation. Furthermore, gold NPs could induce the weakened Ce-O bond which in turn promotes HCHO oxidation.

Origin of tunable photocatalytic selectivity of well-defined α-Fe(2)O(3) nanocrystals.

Visible-light induced degradation of an aqueous mixture containing MO and RhB on well-defined α-Fe2 O3 nanocrystals shows that MO degradation is more favorable and such selectivity on the {012} facet is greater than that on {001}. The origin of selectivity is rationalized as the inherent surface structural difference and preferential molecular adsorption.

Enhanced visible-light hydrogen-production activity of copper-modified ZnxCd(1-x)S.

Copper modification is an efficient way to enhance the photocatalytic activity of ZnS-based materials; however, the mechanisms of Cu(2+) surface and bulk modifications for improving the activity are quite different. In this work, two different synthetic pathways were devised to prepare surface and bulk Cu(2+)-modified Znx Cd1-x S photocatalysts through cation-exchange and coprecipitation methods, respectively. Different Cu(2+) modifications brought different effects on the phase structure, morphology, surface area, optical property, as well as the photocatalytic H2-production activity of the final products. The optimized Cu(2+)-surface-modified Znx Cd1-x S photocatalyst has a high H2-production rate of 4638.5 µmolh(-1) g(-1) and an apparent quantum efficiency of 20.9% at 420 nm, exceeding that of Cu(2+)-bulk-modified catalyst at the same copper content. Cu(2+) surface modification not only brings a new electron-transferring pathway (interfacial charge transfer), but also produces new surface active sites for H2 evolution, reducing the recombination rate of photogenerated charge carriers.