Jingjing Chen

Novel g-C3N4/CoO Nanocomposites with Significantly Enhanced Visible-Light Photocatalytic Activity for H2 Evolution

Novel g-C3N4/CoO nanocomposite application for photocatalytic H2 evolution were designed and fabricated for the first time in this work. The structure and morphology of g-C3N4/CoO were investigated by a wide range of characterization methods. The obtained g-C3N4/CoO composites exhibited more-efficient utilization of solar energy than pure g-C3N4 did, resulting in higher photocatalytic activity for H2 evolution. The optimum photoactivity in H2 evolution under visible-light irradiation for g-C3N4/CoO composites with a CoO mass content of 0.5 wt % (651.3 μmol h-1 g-1) was up to 3 times as high as that of pure g-C3N4 (220.16 μmol h-1 g-1). The remarkably increased photocatalytic performance of g-C3N4/CoO composites was mainly attributed to the synergistic effect of the junction or interface formed between g-C3N4 and CoO.

Ultrathin g-C3N4 nanosheets with an extended visible-light-responsive range for significant enhancement of photocatalysis

Ultrathin graphitic carbon nitride (g-C3N4) nanosheets were synthesized via thermal exfoliation of bulk urea-derived g-C3N4 under an argon atmosphere. As a visible-light responsive photocatalyst, this material exhibits a much superior photocatalytic activity in pollution degradation and H2 evolution than bulk g-C3N4, as a result of the extended region of visible light response and the enhanced surface area of ultrathin g-C3N4 nanosheets. These findings may provide a promising and facile approach to the design of high-performance photocatalysts.

Tunable luminescent Eu2+-doped dicalcium silicate polymorphs regulated by crystal engineering

In this work, tunable luminescence of dicalcium silicate doped with Eu2+ ions is demonstrated based on crystal engineering. Five types of dicalcium silicate polymorphs (γ-, β-, αL′-, αH′-, α-Ca2SiO4) are synthesized by incorporating a crystal-phase stabilizer (CPS), in order to afford variable accommodation frameworks for the Eu2+ activator. Tunable luminescence is observed as the polymorph transforms from one crystal form into another. In addition, the luminescence of Eu2+ in peculiar crystal-phase Ca2SiO4 hosts is further customized by crystal-site engineering, which regulates the coordination environment of Eu2+ in multiple types of Ca2+ sites. The luminescence properties of our Eu2+-doped dicalcium silicate polymorphs show promising prospects for LED lighting applications.

Nitrogen-Deficient Graphitic Carbon Nitride with Enhanced Performance for Lithium Ion Battery Anodes

Graphitic carbon nitride (g-C3N4) behaving as a layered feature with graphite was indexed as a high-content nitrogen-doping carbon material, attracting increasing attention for application in energy storage devices. However, poor conductivity and resulting serious irreversible capacity loss were pronounced for g-C3N4 material due to its high nitrogen content. In this work, magnesiothermic denitriding technology is demonstrated to reduce the nitrogen content of g-C3N4 (especially graphitic nitrogen) for enhanced lithium storage properties as lithium ion battery anodes. The obtained nitrogen-deficient g-C3N4 (ND-g-C3N4) exhibits a thinner and more porous structure composed of an abundance of relatively low nitrogen doping wrinkled graphene nanosheets. A highly reversible lithium storage capacity of 2753 mAh/g was obtained after the 300th cycle with an enhanced cycling stability and rate capability. The presented nitrogen-deficient g-C3N4 with outstanding electrochemical performances may unambiguously promote the application of g-C3N4 materials in energy-storage devices.

Synthesis of CaAlSiN3:Eu2+ nitride phosphors from entire oxides raw materials and their photoluminescent properties

In this work, Eu2+ doped CaAlSiN3 red-emitting nitride phosphors were synthesized for the first time from less-expensive and air-stable entire oxides raw materials, CaCO3, SiO2, Al2O3, and Eu2O3, through a common carbothermal reduction and nitridation (CTRN) method. The synthetic reaction processes involving in this CTRN route and the phase components, photoluminescent properties for the resultant CaAlSiN3:Eu2+ nitride phosphors were investigated in detail. The presented synthesis route using cost-effective entire oxides raw materials for preparation of CaAlSiN3:Eu2+ nitride phosphors shows promising prospect in promoting the application of CaAlSiN3:Eu2+ nitride phosphors in solid state lighting.

Enhanced visible light photocatalytic activity for g-C3N4/SnO2:Sb composites induced by Sb doping

In this paper, g-C3N4/SnO2:Sb composite photocatalysts were fabricated by in situ loading Sb-doped SnO2 (SnO2:Sb) nanoparticles on graphitic carbon nitride (g-C3N4) nanosheets via a facile hydrothermal method. The synthesized g-C3N4/SnO2:Sb composites delivered enhanced visible light photocatalytic performance for degradation of rhodamine B in comparison with g-C3N4/SnO2 composites without doping Sb. Various techniques including XRD, SEM, TEM, FTIR, XPS, PL and electrochemical method were employed to demonstrate the successful fabrication of g-C3N4/SnO2:Sb composite and to investigate the enhanced mechanism of photocatalytic activity. The improvement of visible light absorption and the promotion of separation efficiency and interfacial transfer of photogenerated carriers induced by Sb doping were responsible for the enhancement of photocatalytic activity. This study provides a simple and convenient method to synthesize a visible light responsive catalyst with promising performance for the potential application in environmental protection.

High-temperature crystalline α′H- and α-Ca2SiO4:Eu2+ phosphors stabilized at room temperature by incorporating phosphorus ions

In this work, high-temperature crystalline α′H- and α-Ca2SiO4:Eu2+ phosphors stabilized at room temperature are synthesized by incorporating a suitable amount of phosphorus ions. The crystalline structures and the influence of phosphorus ions on the crystalline phases as well as the photoluminescent properties for phosphorus stabilized α′H- and α-Ca2SiO4:Eu2+ phosphors are investigated in detail. The results indicate that the α′H- and α-Ca2SiO4 high-temperature crystalline phases can be quenched at room temperature with incorporation of 12% and 42% phosphorus ions (replacing Si ions), respectively, shielding the stability effect of Eu2+ ions on the β-form (low Eu2+ concentration) and α′L-form (high Eu2+ concentration). Tunable emissions from green to orange-red light are observed with the increase of the Eu2+ doping concentration in both of α′H-Ca2Si0.88P0.12O4:Eu2+ and α-Ca2Si0.58P0.42O4:Eu2+ phosphors, indicating their promising prospect in applications of LED lighting.

Ppt-level benzene detection and gas sensing mechanism using (C4H9NH3)2PbI2Br2 organic-inorganic layered perovskite

Benzene and formaldehyde are representatives of volatile organic compounds (VOCs), which are harmful to human beings due to their highly toxic and carcinogenic nature. So exploring efficient gas sensing materials to detect ultra-low concentration benzene is of utmost significance. In this paper, an organic–inorganic layered perovskite (C4H9NH3)2PbI2Br2 was synthesized through a facile solution method. And it was employed as a resistive gas sensing candidate to benzene, exhibiting ultrahigh response, fast response–recovery, good selectivity and repeatability for parts per trillion (ppt) level benzene detection at the optimum operation temperature (OOT) of 160 °C, with a response of 90.7 for 1 ppt benzene. In situ infrared analysis confirmed that the gas sensing mechanism is originated from the physical adsorption–desorption of benzene molecules onto the (C4H9NH3)2PbI2Br2 surface, the charge transfer model of which is different from that of conventional metal oxides. A promising application using such organic–inorganic hybrid perovskites for monitoring ultra-low concentration benzene might be interesting to researchers in the gas sensor field.