Fangping Wang

Fabricating a g-C3N4/CuOx heterostructure with tunable valence transition for enhanced photocatalytic activity

Heterostructured g-C3N4/CuOx nanocomposites were successfully prepared with varying the content of g-C3N4 via a mixed solvent-thermal method. Organic ammonia ethanolamine was used as the reductant to adjust the valence of CuOx. Meanwhile, the bulk g-C3N4 was efficiently exfoliated into ultrathin nanoplates during the synthesis process. It is found that the different contents of g-C3N4 can effectively accelerate the valence transition of Cu in the nanocrystals. That is, the successive appearance of CuO and Cu2O with the enhancement of g-C3N4 content. These heterostructured composites were characterized for structural, morphological, elemental distribution, optical properties, specific surface area and photo-generated carrier separation efficiency by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectrum. The photocatalytic performance investigations indicate that the CN5–CuOx is stable enough and shows a remarkable photocatalytic efficiency for degrading methyl orange (MO) under simulated sunlight irradiation, compared with the pure CuOx nanocrystals. The enhanced photocatalytic performance can be attributed to the enlarged surface area, beneficial heterojunction among Cu2O@g-C3N4 and efficient carrier separation efficiency. The abundant Cu substrate in the CuOx nanocrystals functions as a rapid electron/hole pair transfer avenue and inhibits their recombination. Thus the photocatalytic efficiency is tremendously enhanced.

Microwave synthesis of three-dimensional nickel cobalt sulfide nanosheets grown on nickel foam for high-performance asymmetric supercapacitors

A facile and cost-effective microwave method is developed to prepare ternary nickel cobalt sulfide (NiCo2S4) interconnected nanosheet arrays on nickel foam (NF). When acting as an electrochemical supercapacitor electrode material, the as-prepared NiCo2S4/NF shows a high specific capacitance of 1502 F g-1 at a current density of 1 A g-1, and outstanding cycling stability of 91% capacitance retention after 8000 cycles. In addition, a asymmetric supercapacitor (ASC) is composed of NiCo2S4/NF as positive electrode and activated carbon as negative electrode, which exhibits a high energy density of 34.7 W h kg-1 at a power density of 750 W kg-1 and long-term cyclic stability (83.7% capacity retention after 8000 cycles). Even at a high power density of 15 kW kg-1, it still remains an energy density of 17.9 W h kg-1, which is able to light up a light-emitting diode. These findings provide a new and facile approach to fabricate high-performance electrode for supercapacitors.

Bovine serum albumin modified ZnO to degrade organic dyes under ultraviolet light irradiation

Bovine serum albumin (BSA), a non-toxic natural polymer material, is used as a template agent to modify the as-prepared photocatalyst ZnO, changing the ZnO nanorod into a nanosheet. The synthesized samples were characterized by scanning microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR) spectroscopy, photoluminescence (PL) spectroscopy and the Brunauer–Emmett–Teller method (BET). The photocatalytic performance of the samples was evaluated via the photocatalytic degradation process of methylene blue (MB) and phenol under UV-light irradiation. Compared to pure ZnO, the ZnO/BSA composites exhibited superior photocatalytic activity, which could be attributed to the distensible surface area and the effective separation of photoinduced electron–hole pairs. Besides, the BSA used as a template could promote the photocatalysts to absorb more dye particles on its surface and improve degradation performance, which could be applied in a similar fashion between the protein and MB.

A flower-like TiO2 with photocatalytic hydrogen evolution activity modified by Zn(II) porphyrin photocatalysts

The Zn(II)5,10,15,20-tetrakis [m-methoxy-p-hydroxyl-phenyl] porphyrins (ZnTmMpHPP) as a photosensitizer was applied to modified TiO2 and the composite was prepared via a hydrothermal process. The as-obtained flower-like TiO2 and TiO2/ZnTmMpHPP composites were characterized by X-ray diffractometry, scanning electron microscopy, Fourier transform infared spectromotry, transient photocurrent responses and BET. Photocatalytic hydrogen production results show the TiO2/ZnTmMpHPP composite has a higher photocatalytic activity than pure TiO2 under ultraviolet light irradiation, which is due to the enhanced transfer and separation efficiency of photo-induced carriers from the ZnTmMpHPP to TiO2 with the help of conjugated π bond in ZnTmMpHPP. The recycled H2 evolution test indicates that the TiO2/ZnTmMpHPP composite is stable enough under the reaction system. In the presented paper, it is proven that the ZnTmMpHPP can greatly accelerate the separation of charges and effectively improve the photocatalytic H2 evolution activity of TiO2.