JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 105
·期 12
·7548-7557
·
IF 4.186
Sara Adeeba Ismail,Donglin Han
La 2 Ce 2 O 7 is a fluorite-type oxide, showing almost pure oxide ion conduction in dry oxygen atmosphere. Under wet oxygen atmosphere, protons are introduced into La 2 Ce 2 O 7 through hydration reaction, making the material proton-conducting. However, compared with the oxide ion conductivity, the proton conductivity is negligibly small in La 2 Ce 2 O 7 . Here we report the effect of doping trivalent rare earth cations R 3+ ( R = Y, Ho, Er, Yb, or Tm) and elevating partial pressure of water vapor on the proton concentration and conductivity of La 2 Ce 2 O 7 . The samples show single fluorite phases with the doping level up to 0.2, and the solubilities of these dopants were within 0.2–0.3 in La 2 Ce 2 O 7 . The proton concentration increased by doping, due to higher amount of hydratable oxygen vacancies, and statistical coordination of oxide ions surrounded by R 3+ in addition to La 3+ . The sample with the Y content ( x ) of 0.05 showed the highest conductivity at 600°C among La 2 (Ce 1− x Y x ) 2 O 7− δ ( x = 0–0.3) samples, possibly due to the balance between the improved hydration ability and decreased mobility of protons with the increasing Y doping level. Then, the dopant content was fixed to 0.05, and La 2 (Ce 0.95 R 0.05 ) 2 O 7− δ ( R = Y, Ho, Er, Tm, or Yb) was prepared. It was found that as the water vapor partial pressure increased, the proton concentration and conductivity increased regardless of the dopants. Y-doped La 2 Ce 2 O 7− δ ha the highest proton concentration and conductivity.
研究领域:
材料科学
·
化学
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DOI
高影响因子
Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 22
·13770-13776
·
IF 10.733
Yu Ding,Bo-Qiang Miao,Yu-Cheng Jiang,Hong-Chang Yao,Xi-Fei Li,Yu Chen
The hydrogen evolution reaction (HER) is an important half-reaction in water electrolysis. According to the Nernst equation, increasing the interfacial proton concentration may be an effective strategy for reducing the overpotential of HER. Herein, based on the interface engineering strategy, we successfully synthesized polyethyleneimine (PEI)-modified nickel phosphide (NiP2) nanosheets on carbon cloth (CC) nanohybrids (denoted as PEI@NiP2-CC). Multiple physical characterizations proved that the PEI molecules are firmly anchored on the NiP2 surface due to strong N–Ni interactions. In both acidic and neutral media, the solution protons increased at the PEI@NiP2-CC/electrolyte interface due to the protonation of the –NH2 groups in the PEI molecules. The effect of the molecular weight (MW) of PEI on the HER activity was explored in detail. The MW-optimized PEI@NiP2-CC nanohybrids showed only 44 and 100 mV overpotentials for HER in acidic and neutral media, respectively, and were much better than un-modified NiP2-CC nanohybrids. This work provides a strong basis for determining the correlativity between surface modification and catalytic activity.
研究领域:
材料科学
·
电化学
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DOI
高影响因子
Small
·
2024
·
IF 13
Lubing Chen,Guanchao Wang,Kazuaki Toyoura,Donglin Han
Oxygen-excess La 2 NiO 4+ δ (LNO) conducts oxide ions, electron holes, and hydroxide ions simultaneously on exposing to wet oxygen, exhibiting the potential as a cathode material in protonic ceramic fuel cells. Since the incorporation of protons in oxygen-excess LNO is via the hydration reaction assisted by interstitial oxide ions, in this work, the concentration of interstitial oxide ions is reduced and increased by substituting Ni with Cu and Co, respectively. A higher concentration of interstitial oxide ions leads to a high proton concentration, indicating the predominant role of interstitial oxide ions in the hydration reaction, different from that in the oxygen-deficient oxides, where protons are introduced by dissociative absorption of water molecules by oxygen vacancies. The theoretical calculation indicates that protons in Co-doped LNO prefer to locate between the interstitial oxide ions and unshared apical oxide ions. A trapping effect is found between protons and the oxide ions near Cu, leading to decreased proton mobility. Protonic conductivity at 400–575 °C is then directly measured by a Hebb–Wagner direct current polarization method with La 0.99 Ca 0.01 NbO 4− δ as the blocking electrode, enabling the observation that Co-doped LNO has the highest protonic conductivity among the samples studied in this work.
研究领域:
材料科学
·
燃料电池研究
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DOI
PubMed
高影响因子
JOURNAL OF RAMAN SPECTROSCOPY
·
2024
·
IF 2.4
Xiujuan Zhang,Yaxin Wang,Yongjun Zhang,Kun Zhang,Ruoning Chu,Fengyi Zhang,Xiaoyu Zhao
Understanding the variation of proton concentration near the surface of the electrochemical interface is of great significance for understanding the mechanism of electrochemical reactions. In this work, 4-Mpy molecules that are protonated and deprotonated depending on the surrounding pH value adsorb on the Au nanoparticle film electrode with high SERS activity, and by virtue of the highly interfacial-sensitive EC-SERS technique, we systematically studied the effects of electrolyte pH value and external voltage on the protonation and deprotonation of 4-Mpy at the interface between Au-NP film electrode and phosphate buffer, to analyze the changes of near-surface proton concentration at the electrochemical interface. It is found that the pH value of the electrolyte plays a decisive role in the protonation process of 4-Mpy at the electrode interface at low reduction voltage (< −0.1 V). In acidic and neutral solution, 4-Mpy exists mainly in protonated form on the electrode surface. However, in alkaline solutions, 4-Mpy exists mainly on the electrode surface in the form of deprotonation. At high reduction voltage (≥ −0.1 V), the protonation and deprotonation of 4-Mpy on the electrode surface are mainly determined by the adsorption structure of 4-Mpy on the electrode surface. At the same time, we conducted a comparative study of 2-Mpy and 4-Mpy molecules and found that the adsorption modes were different depending on the position of the N atom. 2-Mpy is inclined adsorbed on the surface of the Au-NP film electrode, and 4-Mpy is vertically adsorbed on the surface of the Au-NP film electrode.
研究领域:
电化学
·
分析化学
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DOI
高影响因子
Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 36
·17771-17777
·
IF 9.931
Yue Zhao,Yu Ding,Bin Qiao,Kai Zheng,Pei Liu,Fumin Li,Shuni Li,Yu Chen
Proton-coupled electrocatalytic reactions, such as the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in acidic media, are very important half-reactions of fuel cells and water electrolysis. Aiming at increasing the interfacial proton concentration to improve the ORR/HER activity, we synthesize PdNi alloy nanostructures (PdNi-ANSs)–polyethyleneimine (PEI) inorganic–organic nanocomposites (PdNi-ANSs@PEI) by a PEI assisted cyanogel-reduction strategy. Various physical characterization techniques show that PdNi-ANSs are successfully functionalized by the PEI polymer during the synthesis of PdNi-ANSs@PEI because of the N–Pd interaction. Thanks to the increased interfacial proton concentration caused by the protonation of amine groups at PEI in acidic media, the molecular weight optimized PdNi-ANSs@PEI exhibit enhanced ORR/HER activity compared to PdNi-ANSs without PEI and commercial electrocatalysts, which indicates that the electrocatalytic activity of metal nanostructures can be remarkably improved by reasonable interface design.
研究领域:
电化学
·
材料科学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
SOLID STATE IONICS
·
2025
·
IF 3.3
Sara Adeeba Ismail,Lulu Jiang,Hui Guo,Wenhao Li,Donglin Han
Ba 7 Nb 4 MoO 20 has acceptably high ionic conductivity at 600–800 °C and is attractive for potential application in high temperature solid state electrochemical devices. Up to now, most of the research focuses on isovalent and donor-doping to improve the electrical properties of Ba 7 Nb 4 MoO 20 . In this work, an acceptor-doping strategy was taken by doping Sc and Zr to partially substitute Nb. More vacant oxygen sites thereby form for charge compensation, leading to the increasing proton concentration following the compositional sequence of hydrated Ba 7 Nb 4 MoO 20 < Ba 7 Nb 3.97 Zr 0.03 MoO 19.985 < Ba 7 Nb 3.97 Sc 0.03 MoO 19.97 . Notably, both the H 2 O/D 2 O isotope effect and EMF measurements indicate that the proton conduction – if there is any – is negligibly small, and the Sc and Zr-doped Ba 7 Nb 4 MoO 20 is essentially an oxide ion conductor in the temperature range studied in this work.
研究领域:
材料科学
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固体离子学
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电化学
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DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Gaopeng Zhou,Ying Li,Yadan Luo,Xi Wang,Yushi Ding
In this article, the structure and electrical properties of BaSn 0.15 Ce 0.35 Hf 0.25 Y 0.1 Yb 0.1 Ho 0.05 O 3-δ (referred as BSCHYYbHo in forthcoming discuss) high-entropy ceramic have been investigated. The BCHYYb (short for BaCe 0.5 Hf 0.3 Y 0.1 Yb 0.1 O 3-δ ) and BSCHYYbHo pellets were synthesized successfully by the solid-state reaction method. The XRD detection results indicate that there is no secondary phase appeared in BSCHYYbHo and the lattice constant decrease compared to BCHYYb. The surface SEM and EDS images illustrates that BSCHYYbHo is denser than BCHYYb and the elements distribution is more uniform. The DFT calculation proves that BSCHYYbHo has a tend to maintain single phase structure. The electrical properties of BSCHYYbHo is obtained by the DRT analysis and equivalent circuit method based on defect equilibria model. The total conductivity of BSCHYYbHo is about 2.02 × 10 -4 ∼1.01 × 10 -2 S·cm -1 and standard molar hydration enthalpy of BSCHYYbHo is recorded as − 81.8 kJ/mol. Further, the proton, oxygen vacancies and electron holes conductivity activation energies in BSCHYYbHo is estimated to be 0.45 eV, 1.41 eV and 1.60 eV, respectively. Compared to BCHYYb, BSCHYYbHo electrolyte has higher proton concentration and proton transference number. Overall, BSCHYYbHo ceramic with dense structure and high proton transference number is a potential material for application.
研究领域:
材料科学
·
电化学
·
陶瓷
·
固体化学
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产品关联
DOI
高影响因子
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