Yuxiu Sun

Preparation of Novel Three-Dimensional NiO/Ultrathin Derived Graphene Hybrid for Supercapacitor Applications

A new type of three-dimensional (3D) NiO/ultrathin derived graphene (UDG) hybrid on commercial Ni foam (NF) for a binder-free pseudocapacitor electrode is presented. NiO nanoflakes are in situ grown by a chemical bath deposition (CBD) technique on the free-standing 3D UDG/NF scaffold, which is first prepared by a simple nanocasting process consisting of hydrothermal reaction and subsequent thermal transformation. The 3D UDG/NF scaffold with interconnected network affords a high conductivity due to the high graphitization degree and efficiently facilitates the electron transport to NiO. Moreover, the 3D NiO/UDG/NF hybrid allows for a thinner 3D active material layer under the same loading density, which could shorten the diffusion paths of ions. The NiO/UDG/NF hybrid is directly used as a binder-free supercapacitor electrode, which exhibited significantly improved supercapacitor performance compared to the bare CBD prepared NiO/NF electrode.

Novel non-hydrazine solution processing of earth-abundant Cu2ZnSn(S,Se)4 absorbers for thin-film solar cells

A novel non-hydrazine precursor solution followed by dip-coating has been developed to produce Cu2ZnSnS4 (CZTS) and Cu2ZnSn(S,Se)4 (CZTSSe) thin films. The precursor solution is based on an ethanol solution of metal–thioacetamide (TAA) complex with monoethanolamine (MEA) as the additive agent. By forming coordination complexes with TAA, metal cations are found to have good solubility in ethanol–MEA solvents, producing molecular-level blending in metal precursor solutions. All the materials are low-cost and environmentally friendly. The annealing treatments are conducted under vacuum and Se vapor to form CZTS and CZTSSe absorber films. A solar cell fabricated with the CZTSSe thin film exhibits power conversion efficiency of 5.36%, which is much higher than that (2.86%) of the cell using the CZTS thin film as absorber.

One-step approach to novel Bi4V2O11 hierarchical hollow microspheres with high visible-light-driven photocatalytic activities

New visible-light-sensitive hierarchical Bi4V2O11 hollow microspheres have been successfully synthesized by a facile template-free solvothermal route. The hierarchical Bi4V2O11 superstructure was constructed of single-crystalline nanoplates with a porous surface. A possible growth pattern and formation mechanism of hierarchical Bi4V2O11 hollow microspheres was proposed. The Brunauer–Emmett–Teller (BET) surface area of the hollow sample was 84.613 m2 g−1, which was much higher than other prepared Bi4V2O11 powders. The hierarchical Bi4V2O11 hollow microspheres exhibited excellent visible-light-driven photocatalytic activity for the degradation of Rhodamine-B (RhB). The improved photocatalytic performance could be ascribed to the high specific surface area, the narrow band gap and unique hierarchical hollow structure. The resulting hierarchical Bi4V2O11 hollow microspheres are very promising photocatalysts for degrading organic pollutants and other applications.

Reaction routes for the formation of a Cu2ZnSnS4 absorber material from homogenous ethanol-based solution

Solution-based deposition processes have taken a leading role in producing high efficiency devices from Cu2ZnSnS4 (CZTS) systems. The Cu2ZnSn(S,Se)4 (CZTSSe) films deposited from our ethanol-based process currently provide a high reported efficiency for this material system at 5.36%. In this paper, we report a detailed study of the ethanol-based solution deposition route from the chemistry occurring in the precursor solution to the transformation from solid state framework to the CZTS phase during a subsequent annealing treatment. The homogenous CZTS precursor solution is a mixture of three different metal–thioacetamide (TAA) complexes, which has been proven by the analysis of UV-vis-near-IR absorption spectra and FT-IR absorption spectra. X-ray diffraction (XRD) and Raman spectroscopy have been employed to track every stage of the reaction route. It is found that the complexes build up an ordered framework upon drying and transform to a CuSn3.75S8 phase and finally to the CZTS phase after subsequent annealing treatments. The relative simplicity of this formation mechanism is beneficial for the performance of the CZTS based solar cells.

Self-modified fabrication of inner skin ZIF-8 tubular membranes by a counter diffusion assisted secondary growth method

The ability to fabricate high-quality MOF-based membranes is critical and highly desired due to their outstanding performance in molecule separations and sensors. In this work, a water stable MOF, ZIF-8 is chosen as the typical example to validate a new self-modified counter diffusion assisted secondary growth method for the fabrication of inner skin tubular MOF membranes. The preparation route involves two main steps: counter diffusion for modifying the rough surface of industrial ceramic substrate (plugging pores in the ceramic tube) with homogenous ZIF-8 nanocrystals, and the secondary solvothermal growth for fabricating continuous ZIF-8 membranes on the inner surface of the tubular substrate. The ZIF-8 membranes prepared by this method are characterized in detail. The pre-modification process and the use of a low-reactivity growth solution containing zinc acetate favor the growth of dense ZIF-8 membrane in the solvothermal process.

Retracted article: The synthesis of Cu2Zn(GexSn1−x)Se4 nanocrystals with tunable band gaps

We, the named authors, hereby wholly retract this CrystEngComm article due to data fabrication in Fig. 4 and 6. One of the spectra in Fig. 4, corresponding to nanocrystals of varying Sn/Ge content, has been copied and shifted within the figure: the purple spectrum (x = 1) is the copy of the black spectrum (x = 0). One of the plots in Fig. 6b, corresponding to nanocrystals of varying Sn/Ge content, has been copied and shifted: the blue curve (x = 0.3) is the copy of the green curve (x = 0.7). An investigation by Dr Yongping Lei (Professor and Chairman of College Council of the College of Materials Science and Engineering, Beijing University of Technology, China) determined that Kai Zong was responsible for these instances of data fabrication. Hao Wang, as his tutor and also corresponding author, is responsible for the duty of supervision and management. Other co-authors accept joint responsibility for the preparation of article. Please allow us to sincerely apologise to all readers and the Editorial Office.Signed: Kai Zhong, Si Heng Lu, Hao Wang, Yu Xiu Sun, Hui Juan Zheng, Jing Bing Liu, Hui Yan, 25 November 2013. This retraction is endorsed by Jamie Humphrey, Editor, CrystEngComm. Retraction published 13 December 2013.

Retraction Note: Cu2ZnSnSe4 quantum dots with controllable size and quantum confinement effect

Cu2ZnSnSe4 quantum dots (QDs) with controllable sizes have been synthesized via a hot-injection method. The diameters of the QDs range from 3.2 to 10.1 nm with the tunable band gap from 1.27 to 1.54 eV by adjusting the reaction temperatures from 180 to 240 °C. Structural and Raman scattering data confirm that Cu2ZnSnSe4 is obtained without other secondary phases. The band gaps of the QDs with diameters less than 4.6 nm show an obvious blue shift to higher energy due to quantum confinement effect. It indicates that the Cu2ZnSnSe4 QDs can be a potential candidate for quantum-dot-sensitized solar cells in the future.

Retracted article: In situ formed ternary-based hybrid ink for the fabrication of Cu2ZnSn(S,Se)4 solar cell absorbers

We, the named authors, hereby wholly retract this Journal of Materials Chemistry A article due to data fabrication in Figures 3 and 6. The Raman spectra reported as a CZTSe film in Figure 3b is identical to the Raman spectra reported as CZTSe nanocrystals in Figure 4 of “The synthesis of Cu2Zn(GexSn1−x)Se4 nanocrystals with tunable band gaps”, CrystEngComm, 2013, 15, 6942 [DOI: 10.1039/c3ce40953h]. The UV-vis absorption spectra curves in Figure 6b of films of varying S/Se content are the same curve that has been copied, shifted and pasted within the figure: the purple curve is the copy of the blue curve. An investigation by Dr Yongping Lei (Professor and Chairman of College Council of the College of Materials Science and Engineering, Beijing University of Technology, China) determined that Kai Zong was responsible for these instances of data fabrication. Hao Wang, as his tutor and also corresponding author, is responsible for the duty of supervision and management. Other co-authors accept joint responsibility for the preparation of article. Please allow us to sincerely apologise to all readers and the Editorial Office. Signed: Kai Zong, Yuxiu Sun, Yongzheng Zhang, Hao Wang, Jingbing Liu and Hui Yan, November 2013. Retraction endorsed by Liz Dunn, Managing Editor, Journal of Materials Chemistry A.