•Hedgehog-like mesoporous rutile TiO2 is synthesized by a solvothermal method.•The optimization of solvothermal system is explored.•The formation mechanism of hedgehog-like mesoporous rutile TiO2 is proposed.•Exceptional lithium storage capacity and improved high rate cyclability are obtained.Hedgehog-like mesoporous rutile TiO2 (HLR-TiO2) composed of well-defined nanoneedles is fabricated in a solvothermal system containing tetrabutyl titanate, hydrochloric acid aqueous solution and diethylene glycol with a proper volume ratio. A possible formation mechanism of the HLR-TiO2 is proposed on the basis of different experimental results and three different morphologies are obtained by changing the solvent with other conditions unchanged. Given its unique hierarchical mesoporous nanostructures, the HLR-TiO2 shows superior lithium storage properties with excellent discharge specific capacity of 243.3 mA h g−1 obtained after 100 cycles at a current rate of 1 C among the three samples, which is almost unparalleled to other rutile TiO2-based electrodes. In particular, a specific capacity of 80.2 mA h g−1 is still maintained after 2000 cycles even at a high current rate of 20 C, indicating that great potential of HLR-TiO2 as an electrode material for lithium-ion batteries (LIBs).

Upconversion/semiconductor submicron hollow spheres composed of inner NaxGdFyOz:Yb/Er shell and outer TiO2 shell (denoted NaxGdFyOz:Yb/Er@TiO2) were, for the first time, crafted by exploiting colloidal carbon spheres as the scaffold. The hollow spheres were then incorporated into the TiO2 nanoparticle film photoanode to yield dye-sensitized solar cells (DSSCs) with improved performance. The implementation of NaxGdFyOz:Yb/Er@TiO2 hollow spheres in DSSCs imparted the light trapping due to the light scattering from submicron hollow spheres, and the harvesting of near infrared solar photons by the upconversion material (i.e., dual functionalities), thereby resulting in an increased short-circuit current density Jsc, and thus an improved power conversion efficiency PCE. The electrochemical impedance spectroscopy measurements were performed to scrutinize the interfacial charge transfer characteristics of DSSCs. The measurements revealed that when NaxGdFyOz:Yb/Er hollow spheres without the deposition of TiO2 shell were integrated in the photoanode, a high charge transfer resistance was found. In stark contrast, the judicious decoration of NaxGdFyOz:Yb/Er hollow spheres with a thin layer of TiO2 shell markedly improved the contact between the resulting NaxGdFyOz:Yb/Er@TiO2 shell/shell hollow spheres and the TiO2 nanoparticle film photoanode, leading to a much decreased charge transfer resistance. Taken together, compared to the PCE of 6.81% for the pristine device, the DSSC assembled with the introduction of 8 wt% NaxGdFyOz:Yb/Er@TiO2 hollow spheres in the photoanode exhibited an optimal PCE of 7.58% and a maximum short-circuit current density Jsc of 18.72 mA cm−2 under AM 1.5G one sun illumination, corresponding to 11.31% performance enhancement. As such, the implementation of upconversion submicron hollow materials in photoanode may stand out as an intriguing strategy to improve the device performance of DSSCs.

LiMnPO4 nanoplates with a thickness of ca. 13 nm have been synthesised by a facile solvothermal approach in mixed water-DEG (diethylene glycol) solvents with the mediation of CTAB (cetyltrimethyl ammonium bromide). The coordinative effect of CTAB and DEG promotes the crystal orientation growth of LiMnPO4 along ac plane. The structure and morphology of the product were characterized by XRD, SEM, TEM, BET, FT-IR and Raman spectra. A possible formation mechanism of LiMnPO4 nanoplates assembled in layer-by-layer style is put forward on the basis of the above characterization results. A continuous and uniform carbon layer is coated on the surface of the LiMnPO4 nanoplates after heat treatment with sucrose. The obtained LiMnPO4/C composite exhibits high discharge capacities of 148.6 mA h g−1 at 0.1 C, 127.6 mA h g−1at 1 C and 93.8 mA h g−1 at 5 C and it possesses excellent cycling performance with capacity retention ratios of 96.9% and 92.7% after 100 cycles and 500 cycles at 0.1 C and 1 C, respectively.

•Pt-Ru alloy acts as the catalyst of counter electrodes in dye-sensitized solar cell.•Ni-P/FTO (fluorine-doped SnO2) substrate is prepared by electroless plating method.•Pt-Ru/Ni-P/FTO counter electrode is fabricated by electrodeposition method.•The Ni-P sublayer improves the conductivity and light reflectance of FTO substrate.•The cell with Pt-Ru/Ni-P/FTO counter electrode exhibits an improved efficiency.In this paper, Pt-Ru/Ni-P/FTO has been designed and fabricated as the counter electrode for dye-sensitized solar cells. The Pt-Ru catalytic layer and Ni-P alloy sublayer are prepared by traditional electrodeposition method and a simple electroless plating method, respectively, and the preparation conditions have been optimized. The scanning electron microscopy (SEM) images show that the Pt-Ru particles are evenly distributed on FTO and Ni-P/FTO substrate. By X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), it is confirmed that the Ni-P amorphous alloy has been formed, and no other compounds involved Ni and P have been formed. The electrochemical measurement results reveal that the Pt-Ru electrode has higher catalytic activity and stability towards tri-iodine reduction reaction than Pt electrode in the organic medium. The Ni-P sublayer deposited on FTO glasses increases the conductivity and light-reflection ability of the counter electrode, and this contributes to lowering the inner resistance of the cell and improving the light utilization efficiency. Through the photovoltaic test, it is confirmed that the energy conversion efficiency of a single DSSC with the optimized Pt-Ru/Ni-P/FTO counter electrode is increased by 29% compared with that of the cell based on the Pt/FTO counter electrode under the same conditions.

Ruthenium oxide particles were supported on graphene sheets (GS) by hydrothermal and low temperature annealing process. The GS was prepared from graphene oxide by an expansion process and different expanding temperatures were studied and polystyrene sulfonate sodium was used as dispersion agent of hydrophobic GS. Different Ru content of the RuO2/GS composites on the influence of the electrochemical properties was studied. Atomic force microscope analysis was applied to test the layers of GS. The morphology of GS and RuO2/GS composites were confirmed by field emission transmission electron microscopy analysis. X-ray diffraction, Raman spectroscopy and liquid-nitrogen cryosorption were used to characterize the structure and morphology of the GS and RuO2/GS. The RuO2/GS (Ru:40 wt%) composites used as electrode materials of supercapacitors exhibited a specific capacitance of 551 F/g at 1 A/g in 1 M H2SO4 electrolyte. Besides, both the rate capability and cycle performance of RuO2/GS composites had a great improvement compared with GS.

Upconversion/semiconductor submicron hollow spheres composed of inner NaxGdFyOz:Yb/Er shell and outer TiO2 shell (denoted NaxGdFyOz:Yb/Er@TiO2) were, for the first time, crafted by exploiting colloidal carbon spheres as the scaffold. The hollow spheres were then incorporated into the TiO2 nanoparticle film photoanode to yield dye-sensitized solar cells (DSSCs) with improved performance. The implementation of NaxGdFyOz:Yb/Er@TiO2 hollow spheres in DSSCs imparted the light trapping due to the light scattering from submicron hollow spheres, and the harvesting of near infrared solar photons by the upconversion material (i.e., dual functionalities), thereby resulting in an increased short-circuit current density Jsc, and thus an improved power conversion efficiency PCE. The electrochemical impedance spectroscopy measurements were performed to scrutinize the interfacial charge transfer characteristics of DSSCs. The measurements revealed that when NaxGdFyOz:Yb/Er hollow spheres without the deposition of TiO2 shell were integrated in the photoanode, a high charge transfer resistance was found. In stark contrast, the judicious decoration of NaxGdFyOz:Yb/Er hollow spheres with a thin layer of TiO2 shell markedly improved the contact between the resulting NaxGdFyOz:Yb/Er@TiO2 shell/shell hollow spheres and the TiO2 nanoparticle film photoanode, leading to a much decreased charge transfer resistance. Taken together, compared to the PCE of 6.81% for the pristine device, the DSSC assembled with the introduction of 8 wt% NaxGdFyOz:Yb/Er@TiO2 hollow spheres in the photoanode exhibited an optimal PCE of 7.58% and a maximum short-circuit current density Jsc of 18.72 mA cm−2 under AM 1.5G one sun illumination, corresponding to 11.31% performance enhancement. As such, the implementation of upconversion submicron hollow materials in photoanode may stand out as an intriguing strategy to improve the device performance of DSSCs.