Direct Z-scheme system of UiO-66 cubes wrapped with Zn0.5Cd0.5S nanoparticles for photocatalytic hydrogen generation synchronized with organic pollutant degradation.

Optimized fabrication of Z-scheme photocatalyst based on MOF materials offers sustainable energy generation and environmental improvement due to their attractive properties. The Z-scheme heterojunctions consisting of UiO-66 cubes covered with Zn0.5Cd0.5S nanoparticles were fabricated by a facile solvothermal method. Thanks to the Z-scheme carrier transport under simulated sunlight irradiation, UiO-66@Zn0.5Cd0.5S exhibited enhanced photocatalytic performance of H2 generation synchronized with organic pollutant degradation in fluoroquinolone antibiotic wastewater. Synergistically, the highest comprehensive performance was obtained in ciprofloxacin solution. The H2 yield reached 224 µmol∙ g-1∙ h-1 and simultaneously the removal efficiency was up to 83.6 %. The degradation pathways revealed that the process of piperazine ring cleavage and decarboxylation also generates H protons, further promoting the production of H2. Therefore, the effective spatial separation and transfer of the photoinduced carriers are attributed to the good band structure, large specific surface area, and cooperative reduction and oxidation reactions of UiO-66@Zn0.5Cd0.5S, resulting in significant photocatalytic activity. The toxicity assessment of antibiotics and intermediate products during the photocatalytic reaction also verifies the reduction of environmental risk. This study highlights a promising way to expand the application of the MOFs-based photocatalyst in clean energy conversion coupling with water remediation.

Fabrication of CdLa2S4@La(OH)3@Co3S4 Z-scheme heterojunctions with dense La, S-dual defects for robust photothermal assisted photocatalytic performance.

Optimize the separation and transport mechanism of photogenerated carriers in heterojunction composites, and make full use of the active sites of each material are key factors to enhance photocatalytic activity. Herein, we successfully synthesize defective CdLa2S4@La(OH)3@Co3S4 (CLS@LOH@CS) Z-scheme heterojunction photocatalysts through a facile solvothermal method, which show broad-spectrum absorption and excellent photocatalytic activity. La(OH)3 nanosheets not only greatly increase the specific surface area of photocatalyst, but also can be coupled with CdLa2S4 (CLS) and form Z-scheme heterojunction by converting irradiation light. In addition, Co3S4 with photothermal properties is obtained by in-situ sulfurization method, which can release heat to improve the mobility of photogenerated carriers, and also be used as a cocatalyst for hydrogen production. Most importantly, the formation of Co3S4 leads to a large number of sulfur vacancy defects in CLS, and thus improving the separation efficiency of photogenerated electrons and holes, and increasing the catalytic active sites. Consequently, the maximum hydrogen production rate of CLS@LOH@CS heterojunctions can reach 26.4 mmol g-1h-1, which is 293 times than pristine CLS (0.09 mmol g-1h-1). This work will provide a new horizon for synthesizing high efficiency heterojunction photocatalysts through switching the separation and transport modes of photogenerated carrier.

Efficient Gas-Sensing for Formaldehyde with 3D Hierarchical Co3O4 Derived from Co5-Based MOF Microcrystals.

Detecting formaldehyde at low operating temperature and maintaining long-term stability are of great significance. In this work, a hierarchical Co3O4 nanostructure has been fabricated by calcining Co5-based metal-organic framework (MOF) microcrystals. Co3O4-350 particles were used for efficient gas-sensing for the detecting of formaldehyde vapor at lower working temperature (170 °C), low detection limit of 10 ppm, and long-term stability (30 days), which not only is the optimal value among all reported pure Co3O4 sensing materials for the detection of formaldehyde but also is superior to that of majority of Co3O4-based composites. Such extraordinarily efficient properties might be resulted from hierarchically structures, larger surface area and unique pore structure. This strategy is further confirmed that MOFs, especially Co-clusters MOFs, could be used as precursor to synthesize 3D nanostructure metal oxide materials with high-performance, which possess high porosity and more active sites and shorter ionic diffusion lengths.

Synthesis of a Ni2P/Ni12P5 bi-phase nanocomposite for the efficient catalytic reduction of 4-nitrophenol based on the unique n-n heterojunction effects.

A novel heterostructure catalyst of Ni2P/Ni12P5 has been fabricated through a simple solvothermal method by modifying the molar ratio of the initial raw materials. The products are characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), nitrogen adsorption and X-ray photoelectron spectroscopy (XPS). It is found that the two phases, Ni2P and Ni12P5, are interlaced with one another in the as-formed nanocomposite, resulting in more interfaces. The bi-phase catalyst exhibits a markedly enhanced catalytic activity in the reduction of 4-nitrophenol, as compared to that of single Ni2P or Ni12P5. The enhanced catalytic activity can be attributed to the unique n-n series effects, which result in the increased ease of electron transfer over the Ni2P/Ni12P5 bi-phase catalyst.

Preparation and Characterization of SnO2/Ag Hollow Microsphere via a Convenient Hydrothermal Route.

SnO2/Ag hollow microsphere, assembled form SnO2 and Ag nanoparticles, was synthesized via a facile one-step hydrothermal synthesis method using Na2SnO3.3H2O, CO(NH2)2 and AgNO3 as raw materials. XRD, SEM, and TEM results revealed that the obtained SnO2/Ag hollow microsphere with diameters of ca.3-5 µm was built from uniformly distributed rutile SnO2 and cubic Ag nanoparticles. Moreover, XPS results indicate the existence of strong interaction between Ag and SnO2 nanoparticles, rather than simply physical contact, endowing the SnO2/Ag hollow microspheres with excellent photocatalytic performance in the degradation of RhB solution under visible light irradiation.

Flexible membranes of MoS2/C nanofibers by electrospinning as binder-free anodes for high-performance sodium-ion batteries.

A flexible membrane consisting of MoS2/carbon nanofibers has been fabricated by a simple electrospinning method. MoS2 nanosheets are uniformly encapsulated in the inter-connected carbon nanofibers with diameters of ~150 nm. When evaluated as a binder-free electrode for sodium-ion batteries, the as-obtained electrode demonstrates high performances, including high reversible capacity of 381.7 mA h g(-1) at 100 mA g(-1) and superior rate capability (283.3, 246.5 and 186.3 mA h g(-1) at 0.5, 1 and 2 A g(-1), respectively). Most importantly, the binder-free electrode made of MoS2 and carbon nanofibers can still deliver a charge capacity of 283.9 mA h g(-1) after 600 cycles at a current density of 100 m A g(-1), indicating a very promising anode for long-life SIBs.

Self-assembled 3D hierarchical sheaf-like Nb3O7(OH) nanostructures with enhanced photocatalytic activity.

Novel three-dimensional (3D) hierarchical Nb3O7(OH) nanostructures with a sheaf-like nanoarchitecture were fabricated for the first time by a hydrothermal process. Interestingly, the nanosheafs are composed of nanorods with an average diameter of about 25 nm. The as-prepared 3D hierarchical nanostructures possess a high surface area of 77 m(2) g(-1) with pore diameters of ca. 4.2-12.5 nm. A possible growth mechanism based on the combined Ostwald ripening and self-assembly process was proposed. It is found that both the valence-band top and the conduction-band bottom consist of O 2p and Nb 4d orbitals. Importantly, the 3D hierarchical Nb3O7(OH) nanostructures exhibit enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) under UV-visible light, which is attributed to the unusual hierarchical structure, high surface area, and hybridization of energy bands.

Electrospun sillenite Bi12MO20 (M = Ti, Ge, Si) nanofibers: general synthesis, band structure, and photocatalytic activity.

Sillenite Bi12MO20 (M = Ti, Ge, Si) nanofibers have been fabricated through a facile electrospinning route for photocatalytic applications. Uniform Bi12MO20 (M = Ti, Ge, Si) nanofibers with diameters of 100-200 nm and lengths of up to several millimeters can be readily obtained by thermally treating the electrospun precursors. The photocatalytic activities of these nanofibers for degradation of rhodamine B (RhB) were explored under UV-visible light. The band structure and the degradation mechanisms were also discussed. The fibrous photocatalysts of Bi12TiO20, Bi12SiO20 and Bi12GeO20 exhibit different photocatalytic behaviours, which are attributed to the microstructure, band gap, and electronic structures.

Bi4Ti3O12 nanofibers-BiOI nanosheets p-n junction: facile synthesis and enhanced visible-light photocatalytic activity.

A novel p-n junction photocatalyst of Bi4Ti3O12 nanofibers-BiOI nanosheets has been fabricated through a simple and economical technique of electrospinning combined with a successive ionic layer adsorption and reaction (SILAR) process. The products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectra (DRS), and photoluminescence (PL) spectroscopy. The as-formed Bi4Ti3O12 nanofibers are composed of inter-linked nanoparticles of 50-80 nm in size. The thickness of the as-grown BiOI nanosheets is about 10 nm and the size of the BiOI nanosheets increases with the SILAR cycles. In particular, many {001} facets of BiOI nanosheets are exposed, which is favorable to enhance the visible-light photocatalytic activity. The p-n junction photocatalyst exhibits enhanced visible-light-driven photocatalytic activity for decomposition of rhodamine B (RhB) and phenol. The enhanced photocatalytic activity can be attributed to the extended absorption in the visible light region resulting from the BiOI nanosheets and the effective separation of photogenerated carriers driven by the photo-induced potential difference generated at the Bi4Ti3O12-BiOI p-n junction interface.

Synthesis of porous Bi4Ti3O12 nanofibers by electrospinning and their enhanced visible-light-driven photocatalytic properties.

Bi(4)Ti(3)O(12) nanofibers with diameters of 50-100 nm have been fabricated for the first time through a simple and economical technique of electrospinning combined with subsequent calcination. The as-formed Bi(4)Ti(3)O(12) nanofibers are porous and composed of inter-linked nanoparticles of 30-50 nm in size. They exhibit both enhanced visible-light-driven photocatalytic decomposition of rhodamine B (RhB) and favorable recycling capability. It is attributed to not only the macrostructure, such as the morphology, surface texture, and grain shape, but also the intrinsic structures of oxygen vacancies and surface adsorbed oxygen.