Yajun Wang

Hierarchical Macro-meso-microporous ZSM-5 Zeolite Hollow Fibers With Highly Efficient Catalytic Cracking Capability

Zeolite fibers have attracted growing interest for a range of new applications because of their structural particularity while maintaining the intrinsic performances of the building blocks of zeolites. The fabrication of uniform zeolite fibers with tunable hierarchical porosity and further exploration of their catalytic potential are of great importance. Here, we present a versatile and facile method for the fabrication of hierarchical ZSM-5 zeolite fibers with macro-meso-microporosity by coaxial electrospinning. Due to the synergistic integration of the suitable acidity and the hierarchical porosity, high yield of propylene and excellent anti-coking stability were demonstrated on the as-prepared ZSM-5 hollow fibers in the catalytic cracking reaction of iso-butane. This work may also provide good model catalysts with uniform wall thickness and tunable porosity for studying a series of important catalytic reactions.

A photonic crystal-based CdS–Au–WO3 heterostructure for efficient visible-light photocatalytic hydrogen and oxygen evolution

A photonic crystal-based CdS–Au–WO3 heterostructure was constructed on WO3 photonic crystal segments. Highly efficient visible-light-driven hydrogen and oxygen evolution are demonstrated relative to those of single-, two-component and unstructured systems due to good light harvesting of photonic crystals and efficient electron transfer of this heterostructure.

The encapsulation of CdS in carbon nanotubes for stable and efficient photocatalysis

A CdS encapsulated carbon nanotube (CNT) photocatalyst was prepared by a liquid-chemistry method. Through filling of CNTs with CdS, the aggregation of CdS was prevented efficiently by the good confinement effect of CNTs, and the photocatalytic performance of CdS was enhanced by 2.5 times via synergistic integration of the confinement effect of CNTs and heterojunction between CNTs and CdS. The photostability of CdS encapsulated in and attached on CNTs was investigated systematically through methylene blue photocatalytic degradation, X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-atomic emission spectroscopy. The results indicate that the photocorrosion of CdS is successfully suppressed when it is encapsulated in the CNTs. The mechanism analysis suggests that spatial synergy of the CdS and powerful adsorptivity of CNTs are the primary causes for photocorrosion inhibition. Our efforts propose a new scheme to remarkably promote both the photostability and photocatalytic activity of photocorrosion-susceptible photocatalysts.

Crystalline ZnO/ZnSxSe1−x core–shell nanowire arrays for efficient visible-light photoelectrocatalysis

ZnO/ZnSxSe1−x core–shell nanowire arrays on a silicon substrate were successfully prepared via a hydrothermal method followed by chemical vapor deposition (CVD) of the ZnSxSe1−x shell. By optimizing the CVD growth conditions, a crystalline ZnSxSe1−x shell and well-aligned ZnO/ZnSxSe1−x interface were achieved, which plays an important role towards the enhanced performance of photocatalytic activity. The introduction of the crystalline, lattice-matched ZnSxSe1−x shell to ZnO nanowires significantly enhances the photocatalytic and photoelectrocatalytic activity under UV light irradiation. More attractively, after being combined with the ZnSxSe1−x shell, the visible light photoelectrocatalytic activity of the ZnO/ZnSxSe1−x core–shell nanowires is observed. The performance enhancement of ZnO/ZnSxSe1−x core–shell nanowires under irradiation is mainly due to matching lattice and band energy level alignment between the crystalline ZnSxSe1−x shell and ZnO nanowire core. The high crystal quality of the ZnSxSe1−x shell and the band alignment of the ZnO/ZnSxSe1−x core–shell greatly enhance the charge separation efficiency and prolong the life-time of photogenerated charge carriers. Our finding is expected to provide a new insight into the fabrication of novel and high performance nanowire based core–shell photocatalysts.

New insights into the relationship between photocatalytic activity and TiO2–GR composites

TiO2–graphene (TiO2–GR) composites were synthesized via hydrothermal methods in an ethanol–water solvent. The photocatalytic oxidation, photocatalytic reduction and photoelectrochemical properties were systematically investigated to explore the real role of graphene in the TiO2–GR composite photocatalysts. The pollutant degradation and adsorption results strongly indicated that the composited graphene in TiO2–GR cannot enhance the photocatalytic oxidation activity in the degradation of pollutants. The migration process of photo-generated holes in the photocatalytic oxidation reaction is the rate-determining step, which cannot be promoted by the composited graphene in TiO2–GR. However, composited graphene can promote the migration of photo-generated electrons in TiO2–GR due to its excellent conductivity, which mainly enhances the H2 evolution performance and photoelectrochemical properties.

Facile regulation of crystalline phases and exposed facets on Ti3+ self-doped TiO2 for efficient photocatalytic hydrogen evolution

The control of the photocatalytic activity of TiO2 by tailoring their crystalline structure and electronic structure is a current topic of great interest. In the present study, the phase composition and exposed facets on Ti3+ self-doped TiO2 were regulated by simply changing the fluorinion concentration during the hydrothermal synthesis process of TiO2. It was found that the phase composition can be tuned facilely, and the phase transformation process was analyzed by XRD and UV Raman spectroscopy. The introducing fluorinion during the hydrothermal preparation of TiO2 resulted in F-doping and phase transformation. And the F-doping also affects the amount of Ti3+ ions in the TiO2. SEM analysis indicated that the morphology and exposed facets changed with the change in fluorinion concentration, and the ratios of exposed facets are adjustable. Through systematically optimizing these parameters, the TiO2 prepared under fluorinion concentration of 17.5xa0mM showed the excellent photocatalytic performance under full spectrum illumination. The good photocatalytic performance was mainly attributed to the more phase junctions and surface heterojunctions for enhancing charge separation.

Controlled fabrication of TiO 2 /C 3 N 4 core–shell nanowire arrays: a visible-light-responsive and environmental-friendly electrode for photoelectrocatalytic degradation of bisphenol A

AbstractPhotoelectrocatalytic (PEC) oxidation is a promising method in water treatment due to the synergistic effect of photocatalytic (PC) oxidation and electro-oxidation. Up to now, developing visible-light-responsive, efficient and environmental-friendly electrode for PEC degradation application is still a challenge. In this work, novel and environmental-friendly TiO2/C3N4 core–shell nanowire arrays as an electrode were investigated for PEC degradation of bisphenol A (BPA). TiO2 nanowire arrays provide a direct electron pathway, g-C3N4 serves as a stable and environmental-friendly visible light sensitizer, and effective charge spatial separation can be achieved across the well-matched core–shell interface. Compared with TiO2 nanowire arrays, TiO2/C3N4 core–shell nanowire arrays exhibit higher PC and PEC performance. The photocurrent response of the TiO2 nanowire arrays is enhanced about two times after C3N4 shell deposition. And the PEC performance of TiO2/C3N4 core–shell nanowire arrays is significantly enhanced, which is one time higher than that of TiO2 (under 1.0xa0V external potential). The enhancement of PEC performance of TiO2 nanowire arrays after C3N4 modification can be attributed to the synergistic photoelectric effect, well-matched interface and efficient charge separation induced by the type-II TiO2/C3N4 band alignment. Moreover, the intermediate products of BPA degradation by PEC oxidation were analyzed by gas chromatography–mass spectrometry and five specific products were identified, and then two possible pathways for BPA degradation by PEC process were proposed.n