INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2021
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IF 3.871
Ke-Han Wu,Yu Wang,Kuo-Chih Chou,Guo-Hua Zhang
The compound carbide of refractory metal had great potential applications in ultra-high temperature, biomedical and nuclear fields. In the present study, a novel method composed of vacuum carbothermal reduction followed by calcium treatment was proposed to synthesize single-phase compound carbide. It was found that the required temperature for the formation of single-phase Ta 4 HfC 5 solid solution in liquid calcium was above 1573 K. Meanwhile, the single-phase binary carbides (NbTaC 2 ), ternary carbides (TiNbTaC 3 , ZrNbTaC 3 ), quaternary carbides (TiHfNbTaC 4 , ZrHfNbTaC 4 ), pentanary carbides (TiZrHfNbTaC 5 ) and hexanary carbides (TiZrHfVNbTaC 6 ) were also synthesized by the current method. The formation mechanism of the single-phase compound carbide was discussed and two parameters T SS (based on the mixing enthalpy change and mixing entropy change) and δ a (based on the difference of lattice parameter) were proposed for predicting the formation ability of solid solution. It was found that the necessary conditions for formation of solid solution by current method were T SS < 1800 K and δ a < 3.2%. In addition, when the value of T SS was lower than 5.5 × 10 3 ·ln(1/ δ a )-19 × 10 3 , the single-phase compound carbides could be easily synthesized.
研究领域:
材料科学
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化学工程
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冶金学
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产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
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2021
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IF 9.229
Fei Jin,Chao Xu,Hangyu Yu,Xin Xia,Feng Ye,Xin Li,Xiaoze Du,Yongping Yang
The redox cycle of doped CaMnO3−δ has emerged as an attractive way for cost-effective thermochemical energy storage (TCES) at high temperatures in concentrating solar power. The role of dopants is mainly to improve the thermal stability of CaMnO3−δ at high temperatures and the overall TCES density of the material. Herein, Co-doped CaMnO3−δ (CaCoxMn1–xO3−δ, x = 0–0.5) perovskites have been proposed as a promising candidate for TCES materials for the first time. The phase compositions, redox capacities, TCES densities, reaction rates, and redox chemistry of the samples have been explored via experimental analysis and theoretical calculations. The results demonstrate that CaCo0.05Mn0.95O3−δ showed an enhanced redox capacity (1000 °C at pO2 = 10–5 bar) without decomposition and provided the highest TCES density of ∼571 kJ kg–1 reported so far. The effective Co doping tended to increase the valence states of B-site cations in perovskite and facilitate the diffusion of the lattice oxygen atoms into the surface-active oxygen sites. Furthermore, the high cooling rates deteriorated the microstructure of CaCo0.05Mn0.95O3−δ particles and resulted in incomplete heat release, which is instructive to the design and operation of the TCES systems.
研究领域:
材料科学
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能源工程
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产品关联
DOI
PubMed
高影响因子
Advanced Energy Materials
·
2022
·Vol. 12
·期 22
·2200392
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IF 29.698
Peng Zhong,Kazuaki Toyoura,Lulu Jiang,Lubing Chen,Sara Adeeba Ismail,Naoyuki Hatada,Truls Norby,Donglin Han
A significant hydration and protonic conduction in La 2 NiO 4+ δ -based Ruddlesden–Popper (RP) oxides will enable their use as positrode materials in proton ceramic electrochemical cells (PCECs). Unlike perovskite electrolytes and positrode materials, where protons reside and jump on regular oxide ions, RP oxides such as La 2 NiO 4+ δ may contain oxygen interstitials and offer the possibility that protons locate on and migrate by help of these, suggesting a mechanism by which positrodes may operate by triple conduction. Here, theoretical calculations that support proton migration between interstitial oxide ions in the rock-salt layer via unshared oxide ions in the perovskite layer are reported. Furthermore, water contents of pristine La 2 NiO 4+ δ and La 2- x A x NiO 4+ δ ( A = Ca, Sr, Ba) are reported, showing that hydration increases with the level and basicity of the dopant. Hebb-Wagner blocking electrode measurements show significant partial protonic conductivity in all samples. The effects of doping on hydration and of p H 2 O on the p-type conductivity suggest that protons reside primarily on structural oxide ion, but a role of interstitial oxide ions for dissolution and migration of protons cannot be ruled out in cases with oxygen excess. The results are instructive for further studies and optimization of RP oxides as potential positrode materials for PCECs.
研究领域:
材料科学
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电化学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2024
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IF 8.1
Jing-Hui Zhang,Cheng-Xin Li,Shan-Lin Zhang
To addresses the limitations in electrode performance observed at temperatures ≤700 °C, attributed to the low oxygen surface exchange coefficient primarily caused by high Sr surface segregation, we developed an electrode performance enhancement strategy involving A-site alkali metal doping to SrTi 1-x Fe x O 3-δ (STF)-based perovskite. Here, we present the symmetrical electrode material for solid oxide electrochemical cells (SOCs), Sr 0.95 Mg 0.05 Ti 0.3 Fe 0.7 O 3-δ (SMTF), demonstrating a unique combination of excellent symmetrical electrode performance and long-term stability. A-site Mg doping reduces the Sr surface segregation and improves the conductivity but also significantly enhances its electrochemical performance. At 700 °C, the performance of SMTF symmetric cell in both fuel cell and electrolysis modes is 1.5 times higher than that of STF. Moreover, under air atmosphere, SMTF demonstrates stable performance (>1000 h) at 1 A cm −2 , with no degradation observed after 400 h testing under humidified hydrogen conditions. Additionally, SMTF exhibits excellent CO 2 tolerance in CO 2 -rich atmospheres.
研究领域:
材料科学
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能源技术
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DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2024
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IF 8.1
Chenxiao Wang,Kui Liu,Yinghao Wu,Guangjun Zhang,Xuelian Li,Jiaxin Wu,Ruili Sun,Ting Chen,Lang Xu,Shaorong Wang
A-site doping with Ca 2+ , Sr 2+ for the cobalt-free BaFeO 3-δ -based cathode materials for proton-conducting ceramic fuel cells (PCFCs) is studied. The composite Ba 0·8 Ca 0·2 FeO 3-δ (BCF0.2)-BaZr 0.1 Ce 0·7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) and Ba 0·8 Sr 0·2 FeO 3-δ (BSF0.2)-BZCYYb electrode show polarization resistance (R p ) of 0.156 Ω cm 2 and 0.308 Ω cm 2 at 700 °C, respectively. It is found that the Ca or Sr doping not only benefits oxygen vacancy formation and ion migration but also optimizes the surface oxygen reduction reaction (ORR) process. The density functional theory (DFT) calculations show that the Gibbs energies of *OOH and *OH intermediates are decreased, indicating an enhanced surface ORR. The PCFC with BCF0.2-BZCYYb composite cathode achieves the maximum power density of 299.75 mW cm −2 at 700 °C and shows good stability at 650 °C for 65 h under a constant voltage of 0.75 V. These findings suggest that the BCF0.2-BZCYYb has the potential to serve as cobalt-free cathode materials for PCFCs.
研究领域:
材料科学
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能源科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2018
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IF 4.229
Peng Qiu,Ao Wang,Haoyu Zheng,Lichao Jia,Bo Chi,Jian Pu,Jian Li
LaCoO 3-δ (LC)-coated Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) cathode is fabricated by the solution impregnation method and promoted electrochemical performance is obtained. After being coated by LC shell, the polarization resistance can be as low as 0.197 Ω cm 2 and the peak power density is 0.243 W cm −2 at the operating temperature of 600 °C. The excellent CO 2 resistance of LC-coated BSCF cathode is verified by the CO 2 -poisoning test. Even in the operating atmosphere with high CO 2 concentration, the polarization resistance change of LC-coated BSCF cathode is much smaller than that of the blank BSCF cathode. By long-term test of single cells, the remarkable electrochemical performance stability of LC-coated BSCF cathode is shown. The promoted electrochemical performance, excellent CO 2 resistance and remarkable long-term stability make LC-coated BSCF cathode promising for intermediate temperature solid oxide fuel cells.
研究领域:
材料科学
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能源工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2022
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IF 9.224
Rui Guo,Dongdong Li,Rui Guan,Dechen Kong,Zheng Cui,Ziqi Zhou,Tianmin He
BaCeO3-based proton conductors have comparatively high-proton conductivity, but the low chemical stability and high sintering temperature seriously hinder their practical applications in protonic ceramic fuel cells. Herein, we demonstrate that this limitation can be conciliated by using a triple-doping strategy in a BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte, where the triply doped BaCe0.7Sn0.1Dy0.15Cu0.05O3−δ (BCSDCu) exhibits better chemical stability and conductivity and lower sintering temperature compared with the pristine BZCY. The phase-pure BCSDCu can be obtained at the sintering temperature of 1100 °C prepared by solid-state reaction. The dense BCSDCu (>95%) is achieved at 1350 °C, which is significantly lower than the 1550 °C of BZCY. The BCSDCu presents competitive proton conductivity of 13.6 mS cm–1 under a moist H2 atmosphere at 600 °C. The anode-supported single cell with the BCSDCu (≈40 μm) as the electrolyte reaches the highest power density of 390 mW cm–2 at 600 °C. On the basis of the distribution of relaxation time analysis, we not only distinguish the contribution of grain and grain-boundary conductivities but also identify the rate-determining step of the single-cell performance. The protonic conductivities, mechanical properties, and impurity clean parts induced by grain size effects are discussed for the BCSDCu proton conductor.
研究领域:
材料科学
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）