Browsing by Author "Liu, Yong"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Accelerating multielectron reduction at CuxO nanograins interfaces with controlled local electric field
    (Springer Nature, 2023) Guo, Weihua; Zhang, Siwei; Zhang, Junjie; Wu, Haoran; Ma, Yangbo; Song, Yun; Cheng, Le; Chang, Liang; Li, Geng; Liu, Yong; Wei, Guodan; Gan, Lin; Zhu, Minghui; Xi, Shibo; Wang, Xue; Yakobson, Boris I.; Tang, Ben Zhong; Ye, Ruquan
    Regulating electron transport rate and ion concentrations in the local microenvironment of active site can overcome the slow kinetics and unfavorable thermodynamics of CO2 electroreduction. However, simultaneous optimization of both kinetics and thermodynamics is hindered by synthetic constraints and poor mechanistic understanding. Here we leverage laser-assisted manufacturing for synthesizing CuxO bipyramids with controlled tip angles and abundant nanograins, and elucidate the mechanism of the relationship between electron transport/ion concentrations and electrocatalytic performance. Potassium/OH− adsorption tests and finite element simulations corroborate the contributions from strong electric field at the sharp tip. In situ Fourier transform infrared spectrometry and differential electrochemical mass spectrometry unveil the dynamic evolution of critical *CO/*OCCOH intermediates and product profiles, complemented with theoretical calculations that elucidate the thermodynamic contributions from improved coupling at the Cu+/Cu2+ interfaces. Through modulating the electron transport and ion concentrations, we achieve high Faradaic efficiency of 81% at ~900 mA cm−2 for C2+ products via CO2RR. Similar enhancement is also observed for nitrate reduction reaction (NITRR), achieving 81.83 mg h−1 ammonia yield rate per milligram catalyst. Coupling the CO2RR and NITRR systems demonstrates the potential for valorizing flue gases and nitrate wastes, which suggests a practical approach for carbon-nitrogen cycling.
  • Thumbnail Image
    Item
    Evolution of London penetration depth with scattering in single crystals of K1−xNaxFe2As2
    (American Physical Society, 2014) Kim, H.; Tanatar, M.A.; Liu, Yong; Sims, Zachary Cole; Zhang, Chenglin; Dai, Pengcheng; Lograsso, T.A.; Prozorov, R.
    London penetration depth, λ(T), was measured in single crystals of K1−xNaxFe2As2, x=0 and 0.07, down to temperatures of 50 mK, ∼Tc/50. Isovalent substitution of Na for K significantly increases impurity scattering, with ρ(Tc) rising from 0.2 to 2.2 μΩ cm, and leads to a suppression of Tc from 3.5 to 2.8 K. At the same time, a close to T-linear Δλ(T) in pure samples changes to almost T2 in the substituted samples. The behavior never becomes exponential as expected for the accidental nodes, as opposed to T2 dependence in superconductors with symmetry imposed line nodes. The superfluid density in the full temperature range follows a simple clean and dirty d-wave dependence, for pure and substituted samples, respectively. This result contradicts suggestions of multiband scenarios with strongly different gap structure on four sheets of the Fermi surface.