Chongyin Yang

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Carbon-based supercapacitors can provide high electrical power, but they do not have sufficient energy density to directly compete with batteries. We found that a nitrogen-doped ordered mesoporous few-layer carbon has a capacitance of 855 farads per gram in aqueous electrolytes and can be bipolarly charged or discharged at a fast, carbon-like speed. The(More)
Intrinsic polarization of ferroelectrics (FE) helps separate photon-generated charge carriers thus enhances photovoltaic effects. However, traditional FE with transition-metal cations (M) of d⁰ electron in MO₆ network typically has a band gap (E(g)) exceeding 3.0 eV. Although a smaller E(g) (2.6 eV) can be obtained in multiferroic BiFeO₃, the value is still(More)
Nanostrcutured particles and polycrystalline thin films of Sn-doped chalcopyrite are synthesized by newly-developed methods. Surprisingly, Sn doping introduces a narrow partially filled intermediate band (IB) located ~1.7 eV (CuGaS(2)) and ~0.8 eV (CuInS(2)) above the valance band maximum in the forbidden band gap. Diffuse reflection spectra and(More)
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