Zhiming Xiao

Synthesis of CoS@NiS core/shell nanoarrays as efficient counter electrode for dye-sensitized solar cells

Co3O4@NiO core/shell nanowire arrays were prepared on FTO substrate by a solution-based method and then the Co3O4/NiO were converted to CoS/NiS core/shell structure via an ion-exchange reaction. The dye-sensitized solar cell (DSSC) using CoS/NiS nanowire arrays as the counter electrode (CE) achieves a power conversion efficiency of 6.64%, which is higher than that of samples using individual CoS CE (5.75%) and individual NiS CE (0.64%). This result indicates the unique core/shell structure possesses better catalytic properties. The low cost and high conversion efficiency make the CoS@NiS core/shell nanoarrays competitive as counter electrodes in DSSCs.

Colloidally synthesized MoSe 2 nano-flowers anchored on three-dimensional porous reduced graphene oxide thin films as advanced counter electrode for dye-sensitized solar cells

In this letter, MoSe2 nanosheets with flower-like nanostructure was in-situ grown on pre-coated three-dimensional (3D) porous reduced graphene oxide (rGO) thin films on fluorine-doped tin oxide glass by a facile hydrothermal method. The synergistic effect between the highly catalytic MoSe2 nanostructure and the highly conductive and large surface-area 3D rGO network endows the resultant MoSe2/rGO composite excellent electrocatalytic ability. As expected, dye-sensitized solar cells (DSSCs) prepared with MoSe2/rGO thin films as counter electrode (CE) exhibited a conversion efficiency of 6.56%, which was higher than that of DSSCs with sputtered Pt CE (6.08%).

Controlling the morphology of ultrathin MoS2/MoO2 nanosheets grown by chemical vapor deposition

The morphology of MoS2 plays an important role in its properties and applications, such as electronics and catalysis. Herein, the morphology of as-grown MoS2/MoO2 freestanding nanosheets and 2D MoS2, as synthesized by chemical vapor deposition using S and MoO3 powders as reactants, was studied by tuning the distances between the MoO3 source and the substrate and between the S and MoO3 powder sources. The distance between the MoO3 source and the substrate was deliberately reduced to obtain a sharp gradient of MoO3 precursor concentration on the growth substrate, and the position of S was changed to obtain various sulfur concentrations and initial reaction temperatures. As a result, morphology evolution, including 2D MoS2 and MoS2/MoO2 freestanding nanosheets was observed. A mechanism was proposed to explain the morphology transformation between horizontal 2D flakes and freestanding nanosheets. Based on this mechanism, synthesis methods to produce dense, ultrathin, large-sized MoS2 freestanding nanosheets were proposed. These results may be further generalized to create novel nanostructured devices.The morphology of MoS2 plays an important role in its properties and applications, such as electronics and catalysis. Herein, the morphology of as-grown MoS2/MoO2 freestanding nanosheets and 2D MoS2, as synthesized by chemical vapor deposition using S and MoO3 powders as reactants, was studied by tuning the distances between the MoO3 source and the substrate and between the S and MoO3 powder sources. The distance between the MoO3 source and the substrate was deliberately reduced to obtain a sharp gradient of MoO3 precursor concentration on the growth substrate, and the position of S was changed to obtain various sulfur concentrations and initial reaction temperatures. As a result, morphology evolution, including 2D MoS2 and MoS2/MoO2 freestanding nanosheets was observed. A mechanism was proposed to explain the morphology transformation between horizontal 2D flakes and freestanding nanosheets. Based on this mechanism, synthesis methods to produce dense, ultrathin, large-sized MoS2 freestanding nanosheets w...