Qunqing Hao
Dalian Institute of Chemical Physics
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Featured researches published by Qunqing Hao.
Journal of the American Chemical Society | 2015
Zhiqiang Wang; Bo Wen; Qunqing Hao; Li-Min Liu; Chuanyao Zhou; Xinchun Mao; Xiufeng Lang; Wen-Jin Yin; Dongxu Dai; Annabella Selloni; Xueming Yang
In reduced TiO2, electronic transitions originating from the Ti(3+)-induced states in the band gap are known to contribute to the photoabsorption, being in fact responsible for the materials blue color, but the excited states accessed by these transitions have not been characterized in detail. In this work we investigate the excited state electronic structure of the prototypical rutile TiO2(110) surface using two-photon photoemission spectroscopy (2PPE) and density functional theory (DFT) calculations. Using 2PPE, an excited resonant state derived from Ti(3+) species is identified at 2.5 ± 0.2 eV above the Fermi level (EF) on both the reduced and hydroxylated surfaces. DFT calculations reveal that this excited state is closely related to the gap state at ∼1.0 eV below EF, as they both result from the Jahn-Teller induced splitting of the 3d orbitals of Ti(3+) ions in reduced TiO2. Localized excitation of Ti(3+) ions via 3d → 3d transitions from the gap state to this empty resonant state significantly increases the TiO2 photoabsorption and extends the absorbance to the visible region, consistent with the observed enhancement of the visible light induced photocatalytic activity of TiO2 through Ti(3+) self-doping. Our work reveals the physical origin of the Ti(3+) related photoabsorption and visible light photocatalytic activity in prototypical TiO2 and also paves the way for the investigation of the electronic structure and photoabsorption of other metal oxides.
Nano Letters | 2018
Xiaowei Lu; Qunqing Hao; Mengjia Cen; Guan‐hua Zhang; Ju‐long Sun; Libang Mao; Tun Cao; Chuanyao Zhou; Peng Jiang; Xueming Yang; Xinhe Bao
Noble metals, like Ag and Au, are the most intensively studied plasmonic materials in the visible range. Plasmons in semiconductors, however, are usually believed to be in the infrared wavelength region due to the intrinsic low carrier concentrations. Herein, we observe the edge plasmon modes of Bi2Te3, a narrow-band gap semiconductor, in the visible spectral range using photoemission electron microscopy (PEEM). The Bi2Te3 nanoplates excited by 400 nm femtosecond laser pulses exhibit strong photoemission intensities along the edges, which follow a cos4 dependence on the polarization state of incident beam. Because of the phase retardation effect, plasmonic response along different edges can be selectively exited. The thickness-dependent photoemission intensities exclude the spin-orbit induced surface states as the origin of these plasmonic modes. Instead, we propose that the interband transition-induced nonequilibrium carriers might play a key role. Our results not only experimentally demonstrate the possibility of visible plasmons in semiconducting materials but also open up a new avenue for exploring the optical properties of topological insulator materials using PEEM.
Journal of Physical Chemistry Letters | 2013
Xinchun Mao; Xiufeng Lang; Zhiqiang Wang; Qunqing Hao; Bo Wen; Zefeng Ren; Dongxu Dai; Chuanyao Zhou; Li-Min Liu; Xueming Yang
Journal of Physical Chemistry C | 2015
Xinchun Mao; Zhiqiang Wang; Xiufeng Lang; Qunqing Hao; Bo Wen; Dongxu Dai; Chuanyao Zhou; Li-Min Liu; Xueming Yang
Journal of Physical Chemistry C | 2015
Xinchun Mao; Dong Wei; Zhiqiang Wang; Xianchi Jin; Qunqing Hao; Zefeng Ren; Dongxu Dai; Zhibo Ma; Chuanyao Zhou; Xueming Yang
Physical Chemistry Chemical Physics | 2016
Zhiqiang Wang; Qunqing Hao; Xinchun Mao; Chuanyao Zhou; Dongxu Dai; Xueming Yang
Chinese Journal of Chemical Physics | 2016
Qunqing Hao; Zhiqiang Wang; Xinchun Mao; Chuanyao Zhou; Dongxu Dai; Xueming Yang
Chinese Journal of Chemical Physics | 2015
Zhiqiang Wang; Qunqing Hao; Chuanyao Zhou; Dongxu Dai; Xueming Yang
Chinese Journal of Chemical Physics | 2015
Zhiqiang Wang; Qunqing Hao; Xinchun Mao; Chuanyao Zhou; Zhibo Ma; Zefeng Ren; Dongxu Dai; Xueming Yang
Physical Chemistry Chemical Physics | 2018
Bo Wen; Qunqing Hao; Wen-Jin Yin; Le Zhang; Zhi-qiang Wang; Tianjun Wang; Chuanyao Zhou; Annabella Selloni; Xueming Yang; Li-Min Liu