Xianghua Hu

MnO2 ultralong nanowires with better electrical conductivity and enhanced supercapacitor performances

Single-crystal α-MnO2 ultralong nanowires (∼40 μm in length, ∼15 nm in diameter), which were synthesized by a simple polyvinylpyrrolidone (PVP) assisted hydrothermal route, exhibited a better electrical conductivity, a highest specific capacitance of 345 F g−1 at a current density of 1 A g−1 with high rate capability (54.7% at 10 A g−1) and good cycling stability.

Ni(OH)2/CoO/reduced graphene oxide composites with excellent electrochemical properties

Ni(OH)2/CoO/rGO composites, which were synthesized via a one-step solvothermal route, exhibit excellent electrochemical properties, e.g., a specific capacitance up to 1317 F g−1 at a current density of 2 A g−1 and 1056 F g−1 at 5 mV s−1 with good cyclability.

Excellent electrical conductivity of the exfoliated and fluorinated hexagonal boron nitride nanosheets

The insulator characteristic of hexagonal boron nitride limits its applications in microelectronics. In this paper, the fluorinated hexagonal boron nitride nanosheets were prepared by doping fluorine into the boron nitride nanosheets exfoliated from the bulk boron nitride in isopropanol via a facile chemical solution method with fluoboric acid; interestingly, these boron nitride nanosheets demonstrate a typical semiconductor characteristic which were studied on a new scanning tunneling microscope-transmission electron microscope holder. Since this property changes from an insulator to a semiconductor of the boron nitride, these nanosheets will be able to extend their applications in designing and fabricating electronic nanodevices.

In situ synthesis of P3HT-capped CdSe superstructures and their application in solar cells

Organic/inorganic hybrid solar cells have great potentials to revolutionize solar cells, but their use has been limited by inefficient electron/hole transfer due to the presence of long aliphatic ligands and unsatisfying continuous interpenetrating networks. To solve this problem, herein, we have developed a one-pot route for in situ synthesis of poly(3-hexylthiophene) (P3HT)-capped CdSe superstructures, in which P3HT acts directly as the ligands. These CdSe superstructures are in fact constructed from numerous CdSe nanoparticles. The presence of P3HT ligands has no obvious adverse effects on the morphologies and phases of CdSe superstructures. Importantly, higher content of P3HT ligands results in stronger photoabsorption and fluorescent intensity of CdSe superstructure samples. Subsequently, P3HT-capped CdSe superstructures prepared with 50 mg P3HT were used as a model material to fabricate the solar cell with a structure of PEDOT:PSS/P3HT-capped CdSe superstructures: P3HT/Al. This cell gives a power conversion efficiency of 1.32%.

In situ preparation of CuInS2 films on a flexible copper foil and their application in thin film solar cells

The in situ preparation of semiconductor films on a flexible metal foil has attracted increasing attention for constructing flexible solar cells. In this work, we have developed an in situgrowth strategy for preparing CuInS2 (CIS) films by solvothermally treating flexible Cu foil in an ethylene glycol solution containing InCl3·4H2O and thioacetamide with a concentration ratio of 1 : 2. The effects of solvothermal temperature, time and concentration on the morphology and phase of the CIS films are investigated. Solvothermal temperature has no obvious effect on the morphology of the final films, but higher temperature is favorable for the growth of CIS films with higher crystallinity. Reactant concentration plays a significant role in controlling the morphology of CIS films; if InCl3·4H2O concentration is relatively low (≤0.042 M), single-layered CIS films can be produced, which are composed of high ordered potato chips shaped nanosheets, otherwise, it prefers to form a double-layered film, for which the lower layer is similar CIS ordered nanosheets while the upper layer is composed of flower shaped superstructures. A possible mechanism of the CIS films is also investigated. UV-vis measurements show that all these CIS films possess a direct bandgap energy of 1.48 eV, appropriate for the absorption of the solar spectrum. Finally, single-layered CIS films on Cu foil were employed for fabricating flexible solar cells with a structure of Cu foil/CuInS2/CdS/i–ZnO/ITO/Ni–Al, and the resulting cells yield a power conversion efficiency of 0.75%. Further improvement of the efficiencies of the solar cells can be expected by optimizing the morphology, structure and composition of the CIS films, as well as the fabrication technique.

Synthesis of Cu2ZnSnS4 film by air-stable molecular-precursor ink for constructing thin film solar cells

Cu2ZnSnS4 (CZTS) precursor ink routes have been demonstrated to open up new possible ways to fabricate low-cost and high-efficiency CZTS film solar cells, and a prerequisite is to investigate and develop precursor inks. Herein, we report the synthesis of air-stable molecular precursor ink for the construction of CZTS film solar cells. The precursor ink was prepared by dissolving Cu(acac)2, Zn(acac)2, and SnC2O4 and sulfur powder in pyridine, which yielded a viscous black solution. Subsequently, the precursor ink was spin-coated on a Mo-coated glass substrate, and the resulting film was heated in the air to burn off organics, producing an oxide film. The oxide film was subjected to the sulfurization process, in which the effects of sulfurization conditions on composition were investigated. CZTS film was obtained with Cu/(Zn + Sn) = 0.87 and Zn/Sn = 1.09, which is a composition that is close to the previously proposed composition for high-efficiency CZTS film solar cells. This CZTS thin film was used to construct a solar cell, and it exhibited an initial power conversion efficiency of 2.30%. Further improvement of the efficiency can be expected by the optimization of the ink composition, the composition/morphology/thickness/phase of the CZTS layer, and the device structure.