Yawei Yang

Facile synthesis of ZnO/CuInS2 nanorod arrays for photocatalytic pollutants degradation.

Vertically-aligned ZnO nanorod arrays on a fluorine-doped tin oxide glass substrate were homogeneously coated with visible light active CuInS2 quantum dots by using a controllable electrophoretic deposition strategy. Compared with the pure ZnO nanorod arrays, the formation of high-quality ZnO/CuInS2 heterojunction with well-matched band energy alignment expanded the light absorption from ultraviolet to visible region and facilitated efficient charge separation and transportation, thus yielding remarkable enhanced photoelectrochemical performance and photocatalytic activities for methyl orange and 4-chlorophenol degradation. The ZnO/CuInS2 film with the deposition duration of 80min showed the highest degradation rate and photocurrent density (0.95mA/cm(2)), which was almost 6.33 times higher than that of the pure ZnO nanorod arrays film. The CuInS2 QDs sensitized ZnO nanorod arrays film was proved to be a superior structure for photoelectrochemical and photocatalytic applications due to the optimized CuInS2 loading and well-maintained one-dimensional nanostructure.

TiO2 passivation for improved efficiency and stability of ZnO nanorods based perovskite solar cells

Zinc oxide (ZnO) has been demonstrated to be a superb electron selective contact material in photovoltaic devices for its high electron mobility and various accessible nanostructures. However, issues of severe charge recombination and thermal instability occurring at the perovskites/ZnO interface hinder its application on perovskite solar cells. Herein, we report a strategy of TiO2 passivation onto the surface of ZnO nanorods (NRs) using a wet-chemical method, where a device structure FTO/ZnO NRs/TiO2 passivation layer/CH3NH3PbI3/spiro-OMeTAD/Ag is adopted. Based on the proposed strategy, an overall power conversion efficiency (PCE) of 13.49% is achieved mainly due to the improved open-circuit voltage (Voc) of 1.02 V, shirt-circuit current density (Jsc) of 20.69 mA cm−2, and fill factor (FF) of 0.64, which are much higher than those of bare ZnO NRs-based devices. Interestingly, TiO2 passivated samples show much better long-term device stability than those without passivation, where TiO2 acts as a buffer layer with improved thermal stability owning to reduced chemisorbed hydroxyl groups as indicated by X-ray photoelectron spectroscopy.

Fabrication of Bi2Sn2O7-ZnO heterostructures with enhanced photocatalytic activity

ZnO microspheres synthesized by a hydrolysis method were sensitized with Bi2Sn2O7 (BSO) nanoparticles prepared using a hydrothermal method at different concentrations. Various characterization methods were employed to study the microstructural, morphological, optical and photocatalytic properties of the BSO-ZnO heterostructures. The effect of the BSO concentration on the photocatalytic activity of the as-prepared samples was also investigated. The 12.5BSO-ZnO sample exhibits the highest photocatalytic efficiency. The enhanced photocatalytic efficiency is ascribed to an effective separation of the photogenerated electrons and holes due to the presence of the BSO-ZnO heterojunction.

Construction of High-Quality SnO2@MoS2 Nanohybrids for Promising Photoelectrocatalytic Applications

High-quality three-dimensional (3D) hierarchical SnO2@MoS2 nanohybrids were successfully obtained via a facile but effective wet chemistry synthesis method. Meanwhile, the SnO2@MoS2 hybrid film was fabricated through an electrophoretic deposition method to promote photoelectrocatalytic (PEC) efficiency and solve the recovery problem. Compared with the pure SnO2 and MoS2 films, the SnO2@MoS2 heterostructures could decrease the rate of the photoelectron-hole pairs recombination, which resulted in the superior PEC pollutant degradation and water splitting activities. Meanwhile, the SnO2@MoS2 hybrid films with well-defined 3D hierarchical configurations have large surface areas, abundant active edge sites, and defects on the basal surfaces, which were also advantageous for the PEC activities (for pollutant degradation, apparent rate constant k = 5.91 h-1; for water splitting, onset potential = -0.05 V and current density = 10 mA/cm2). Therefore, the SnO2@MoS2 hybrid film proved to be a superior structure for PEC applications.

Construction of ZnO/Cu2SnS3 nanorod array films for enhanced photoelectrochemical and photocatalytic activity

ZnO nanorod array films grown on fluorine-doped tin oxide glass substrates were homogeneously coated with visible light responsive Cu2SnS3 nanoparticles through a controllable one-step electrodeposition process. The coating of Cu2SnS3 nanoparticles expanded light utilization from the UV to visible region and facilitated charge generation, separation and transportation, thus leading to significantly enhanced photoelectrochemical and photocatalytic performance. The ZnO/Cu2SnS3 nanorod array films with a deposition time of 90 s had the highest apparent rate constant (3.87 × 10−2 min−1) and photocurrent density (0.46 mA cm−2), which were 2.86 and 23.00 times that of the pure ZnO, respectively. The ZnO/Cu2SnS3 nanorod array films were proven to be an advanced structure for photoelectrochemical and recyclable photocatalytic applications due to the maintenance of the optimized Cu2SnS3 nanoparticle coating and array nanostructure.

Synthesis of high quality CuO nanoflakes and CuO–Au nanohybrids for superior visible light photocatalytic behavior

Well-defined CuO nanoflakes and CuO–Au nanohybrids are successfully obtained by a facile but effective wet chemistry synthesis method. Compared with CuO nanoflakes, the formation of high-quality CuO–Au nanohybrids can improve the visible light absorption efficiency, charge generation and separation efficiency through surface plasmon resonance (SPR), thus yielding remarkably enhanced photoelectrochemical and photocatalytic activities. CuO–Au nanohybrids with an optimized Au nanoparticle loading concentration (10 wt%) and particle size (∼15 nm) present the highest photocurrent density (46 μA cm−2) and degradation rate constant (k = 0.64 h−1), which are almost ∼4 times higher than those of the CuO nanoflakes. The high photocatalytic properties and robust synthesis of CuO–Au nanohybrids can expand new material systems for the visible light utilization of solar energy and effective treatment of organic pollutants.

New architecture of a petal-shaped Nb2O5 nanosheet film on FTO glass for high photocatalytic activity

A petal-shaped Nb2O5 nanosheet thin film was grown directly on a transparent conductive fluorine-doped tin oxide (FTO) glass substrate via a facile hydrothermal method. Structural and morphological characterization showed that the Nb2O5 nanosheets with a thickness of about 30 nm stood almost vertically on the FTO glass substrate. The vertical thickness of the petal-shaped Nb2O5 nanosheet array film, which grows along (020) and (003) crystal planes, was 2–3 μm. The petal-shaped Nb2O5 nanosheet array film on FTO glass without annealing showed excellent photocatalytic activity for degrading aqueous rhodamine B. The activity was better than that of the porous P25 film with a thickness of 50 μm. The new architecture is suitable for reuse in photocatalytic applications.

A hydrophobic surface enabled salt-blocking 2D Ti3C2 MXene membrane for efficient and stable solar desalination

Solar steam generation is a renewable, environmentally friendly and low-cost technology for seawater desalination and wastewater remediation. Highly efficient solar evaporation from pure water has been achieved using advanced artificial architectures and hydrophilic light absorption materials, while the long-term steady work for high salinity water desalination becomes a non-negligible problem when it comes to practical use. In terms of this issue, a hydrophobic MXene membrane, which contains a salt-blocking delaminated Ti3C2 nanosheet layer with trimethoxy(1H,1H,2H,2H-perfluorodecyl)silane modification for sunlight harvesting and a piece of commercial filter membrane for water supply, is proposed in this work. With high light utilization, high stability, abundant evaporating channels, rapid water transport through the filter membrane and salt-blocking on the MXene membrane, the as-fabricated self-floatable device achieves a solar evaporation rate of 1.31 kg m−2 h−1 and a solar steam conversion efficiency of 71%, and stability under high salinity conditions under one sun over 200 hours, ensuring the highly efficient and long-term stable photothermal transduction for water purification from seawater and wastewater containing organic dyes and heavy metals. The hydrophobic surface enabled salt-blocking MXene membrane is proved to be an effective, efficient and stable photothermal material for solar desalination.

A general salt-resistant hydrophilic/hydrophobic nanoporous double layer design for efficient and stable solar water evaporation distillation

A novel and elegant hydrophilic/hydrophobic nanoporous double layer structure was designed and developed for efficient long-term water desalination. It contained a hydrophobic salt-resistant hierarchical layer of well-defined Cu2SnSe3 (or Cu2ZnSnSe4) nanosphere arrays for broad solar harvesting and water vapor evaporation, and a hydrophilic filter membrane for continuous water supply and vapor generation. The as-fabricated self-floatable devices achieve remarkable solar water evaporation performances (average evaporation rate: 1.657 kg m−2 h−1 and solar thermal conversion efficiency: 86.6% under one sun) with super stability for water distillation from seawater and wastewater containing organic dyes, heavy metals and bacteria.