Design and synthesis of a novel blue-emitting CaNaSb2O6F:Bi3+ phosphor for optical temperature sensing.

Bi3+ has gained increasing attention due to its abundant reserves, adjustable luminous colour and high chemical stability, therefore, Bi3+-activated luminescent materials have already been extensively applied in various fields. Herein, a novel blue-emitting CaNaSb2O6F:Bi3+ (CNSOF:Bi3+) phosphor with a pyrochlore-type structure with the space group Fd3̄m (277) was successfully synthesized. It exhibits a broad absorption band in the n-UV region (290-390 nm) and an ideal blue emission band centered at 441 nm. Interestingly, the wide emission peak of CNSOF:Bi3+ shows strongly temperature-dependent fluorescence properties and good thermal degradation resistance in the cycle temperature range from 298 K to 473 K, and the relative sensitivity is calculated to reach the maximum value of 2.34% K-1 at 423 K. Besides, the phosphor is different from a traditional optical temperature sensing material which shows the emission peak of trivalent rare earth ions. The wide emission peak makes the instrument insensitive to the peak shift, which dramatically reduces the requirement of the instrument, and the emission peak does not shift with the temperature to enhance the measurement stability, thus saving the cost. These results indicate that the CNSOF:Bi3+ blue emitting phosphor has potential applications in temperature sensing.

Tuning emission color and improving the warm-white persistent luminescence of phosphor BaLu2Al2Ga2SiO12:Pr3+via Zn2+ co-doping.

In this article, we synthesized a series of new warm-white emitting persistent luminescent phosphors by co-doping Zn2+ into Pr3+ activated BaLu2Al2Ga2SiO12, and systematically investigated the effect of Zn2+ co-doping on both their photoluminescence and persistent luminescence properties. Following the removal of UV excitation, the phosphor emits warm-white persistent luminescence consisting of greenish-blue and red emissions originating from 3P0 and 1D2 multiplet electron transitions at the 4f level of Pr3+. The luminescence properties of the Ba1-xZnxLu2Al2Ga2SiO12:Pr3+ phosphors can be modified by changing the content of Ba/Zn in the host, which affects the non-radiative energy flow between 5d1-3P0-1D2 levels and resultantly enhances the intensity of the 4f → 4f transition. Compared with the undoped sample, Zn2+ co-doping can significantly enhance the persistent luminescence intensity of the phosphors in the range of 400-800 nm and reduce the intensity in the UV region. Meanwhile, Zn2+ co-doping can also change the intensity ratio between the greenish-blue and red emissions, and the persistent luminescence color can be tuned from red to warm-white with the increase of Zn2+ concentration. Besides, the Zn2+ ions entering the crystal lattice also enhance the persistent luminescence performance by modifying the defect levels in the phosphor. For the optimized phosphor, bright warm-white persistent luminescence can be observed by the naked eye in the dark after the removal of the excitation source for 4 h. Based on the experimental results, a feasible mechanism was also proposed to reveal the persistent luminescence generation process for the BaLu2Al2Ga2SiO12:Pr3+,Zn2+ phosphor.

High specific capacitance of manganese-based colloidal system with rare earth modification.

Ever-increasing global energy consumption has increased aggregate demand on electrochemical energy storage devices with high energy density. Over the past few decades, manganese oxides have attracted wide attention due to their abundant reserves, low cost, environmental friendliness, and high theoretical capacity. However, most reported manganese-based materials have exhibited capacity far below the theoretical capacity, which was only on the basis of Mn3+/Mn4+ couple. The rich chemistry of manganese enables it to exist in various valence states, such as Mn0, Mn2+, Mn3+, Mn4+, and Mn7+, providing great opportunity for discovering new manganese-based electrode systems. Herein, we formed a Mn2+/Mn4+ couple from a manganese-based colloidal system with rare earth (RE) modification, which was formed in-situ on nickel (Ni) foam in KOH electrolyte under an electric field assistance. The Mn-based colloidal electrode, with Mn:Ce mass ratio of 1:0.5, achieved a high specific capacitance of 2985 F g-1 at 3 A g-1, which was higher than the theoretical capacity of 2193 F g-1 on the basis of the Mn3+/Mn4+ couple. After the addition of Ce3+, the prepared sample exhibited improved rate capability performance. Our manganese-based colloidal electrode with RE modification delivered a high specific capacitance of 1223 F g-1 at 20 A g-1, with 54.5% retention of 2243 F g-1 at 3 A g-1 at Mn:Ce mass ratio of 1:0.05. Colloidal electrode systems involving Mn-based colloids are a novel way to engineer the electrochemical performance of inorganic materials.

High areal capacitance of manganese oxide electrodes with cerium as rare earth modification.

Manganese oxides have attracted wide attention as promising electrode materials for high-energy density supercapacitors. However, the electrochemical performance of the manganese oxide materials deteriorates considerably with the increase in mass loading due to their moderate electronic and ionic conductivities. This phenomenon leads to low areal capacitance, which limits the practical application of these materials. Herein, we perform a potentiostatic electrodeposition of manganese oxides with Ce as rare earth (RE) modification on a nickel (Ni) foam substrate to achieve high areal capacitance. Under optimum conditions, manganese oxide nanosheets are axially grown on Ni foam to form a hierarchically porous network nanostructure, which ensures facile ionic and electric transport. The Ce-modified manganese oxide with the Mn:Ce molar ratio of 1:0.1 yields an outstanding areal capacitance of 3.67 F cm-2 at 2 mA cm-2 and a good rate capability compared with the capacitance of 2.59 F cm-2 at 2 mA cm-2 of pure manganese oxide without the addition of Ce. This result verifies the importance of Ce modification to manganese oxides. Our results suggest the important role played by the RE element Ce in enhancing the electrochemical performance of high areal capacitance manganese oxide electrodes, which is essential to bringing them one step toward further practical applications.

Multifunctional inorganic nanomaterials for energy applications.

Our society has been facing more and more serious challenges towards achieving highly efficient utilization of energy. In the field of energy applications, multifunctional nanomaterials have been attracting increasing attention. Various energy applications, such as energy generation, conversion, storage, saving and transmission, are strongly dependent upon the electrical, thermal, mechanical, optical and catalytic functions of materials. In the nanoscale range, thermoelectric, piezoelectric, triboelectric, photovoltaic, catalytic and electrochromic materials have made major contributions to various energy applications. Inorganic nanomaterials' unique properties, such as excellent electrical and thermal conductivity, large surface area and chemical stability, make them highly competitive in energy applications. In this review, the latest research and development of multifunctional inorganic nanomaterials in energy applications were summarized from the perspective of different energy applications. Furthermore, we also illustrated the unique functions of inorganic nanomaterials to improve their performances and the combination of the functions of nanomaterials into a device. However, challenges may be traced back to the limitations set by scaling the relations between multifunctional inorganic nanomaterials and energy devices.