Browsing by Author "Chen, Kan"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Enhanced thermoelectric performance of Cs doped BiCuSeO prepared through eco-friendly flux synthesis
    (Elsevier, 2017-11-10) Abdenour, Achour; Chen, Kan; Reece, Michael J.; Huang, Zhaorong
    The synthesis of BiCuSeO oxyselenides by a flux method in air has been investigated. A maximum power factor of 230 μWm−1K−2 and a very low thermal conductivity of 0.42 Wm−1K−1 were obtained, leading to a high ZT value of 0.37 at 680 K for pristine BiCuSeO. With Cs doping, a large enhancement in electrical conductivity coupled with a moderate decrease in Seebeck coefficient lead to a power factor of 340 μWm−1K−2 at 680 K. In addition, Cs doping reduced the thermal conductivity further to 0.35 Wm−1K−1 at 680 K. The combination of higher power factor and reduced thermal conductivity results in a high ZT value of 0.66 at 680 K for Bi0.995Cs0.005CuSeO.
  • Thumbnail Image
    ItemOpen Access
    Porous thermoelectric materials for energy conversion by thermoelectrocatalysis
    (Wiley, 2024-07-23) Wu, Jiaqi; Chen, Kan; Reece, Michael J.; Huang, Zhaorong
    Novel uses of thermoelectric (TE) materials as catalyst and catalyst promoters have been reported recently for a variety of applications such as environmental gas mitigation, battery, and photoreduction of nuclear wastewater. TE Seebeck voltage is found to increase the catalytic activities by tens to hundreds of times, and this effect is termed thermoelectrocatalysis. In these uses, the TE materials are in an open-circuit configuration, which is different from the usual closed-circuit configuration in the TE energy generation and cooling devices. A new figure of merit defined as the Seebeck voltage per unit heat loss is proposed for the application of thermoelectrocatalysis. Techniques such as dense bulk porous surface and increased thickness of the TE materials are used for the optimization of the thermoelectrocatalysis of the oxyselenide BiCuSeO for the carbon dioxide hydrogenation reactions.
  • Thumbnail Image
    ItemOpen Access
    Tuning of catalytic activity by thermoelectric materials for carbon dioxide hydrogenation
    (Wiley, 2017-10-06) Achour, Abdenour; Chen, Kan; Reece, Michael J.; Huang, Zhaorong
    An innovative use of a thermoelectric material (BiCuSeO) as a support and promoter of catalysis for CO2 hydrogenation is reported here. It is proposed that the capability of thermoelectric materials to shift the Fermi level and work function of a catalyst lead to an exponential increase of catalytic activity for catalyst particles deposited on its surface. Experimental results show that the CO2 conversion and CO selectivity are increased significantly by a thermoelectric Seebeck voltage. This suggests that the thermoelectric effect can not only increase the reaction rate but also change chemical equilibrium, which leads to the change of thermodynamic equilibrium for the conversion of CO2 in its hydrogenation reactions. It is also shown that this thermoelectric promotion of catalysis enables BiCuSeO oxide itself to have a high catalytic activity for CO2 hydrogenation. The generic nature of the mechanism suggests the possibility that many catalytic chemical reactions can be tuned in situ to achieve much higher reaction rates, or at lower temperatures, or have better desired selectivity through changing the backside temperature of the thermoelectric support.