JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·
IF 3.5
Le Fu,Wenjun Yu,Bohan Wang,Ying Deng
Extensive efforts have been devoted to investigate the distribution of dopants in ceramics. However, one critical question remained barely explored, which is the redistribution of dopants between amorphous and crystalline phases during fast sintering of ceramics. Here we address this gap by observing the redistribution of five selected dopants (Y, Ce, Yb, Hf, and Ta) in ZrO 2 –SiO 2 nanoceramics during sintering. We designed two groups of experiments: In group one, dual-phase amorphous particles were sintered with multicomponent crystalline ones. The former particles were ZrO 2 –SiO 2 glass, whereas the latter ones consisted of ZrO 2 solid-solution nanocrystallites (SSNCs) embedded in an oxide glass containing Zr, Si, Y, Ce, Hf, Yb, and Ta. In group two, dual-phase crystalline particles were sintered with multicomponent amorphous ones. The former particles were composed of ZrO 2 nanocrystallites (NCs) embedded in an amorphous SiO 2 matrix, whereas the latter ones were oxide glass containing Zr, Si, Y , Ce, Hf, Yb, and Ta. Redistribution of the dopants from the glass to ZrO 2 NCs occurred in the two groups, that is, the five dopants migrated from the glass matrix into the ZrO 2 NCs, forming ZrO 2 SSNCs. The redistribution of the dopants not only increased the configuration entropy of the ZrO 2 NCs but also benefited the network structure integrity of SiO 2 glass. The dopant redistribution process was driven by the minimization of the studied material's free energy. The reported results are important for understanding the redistribution behaviors of dopants and are expected to provide new insights to design new ceramics via the multielement co-doping strategy.
研究领域:
材料科学
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陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HYDROLOGY
·
2022
·
IF 6.708
Zhi Dou,Yongqiang Chen,Chao Zhuang,Zhifang Zhou,Jinguo Wang
Increasing human activities in cold regions have led to serious environmental problems due to non-aqueous phase liquids (NAPLs) contamination. However, the NAPLs redistribution driven by freeze–thaw (FT) cycles is not well understood. In this study, the redistribution of NAPLs in porous media subjected to FT cycles in a temperature range from 20 °C to −15 °C was investigated using the low-field Nuclear Magnetic Resonance (NMR) technique. The redistribution of NAPLs in the prepared samples with NAPLs saturation ranging from 13.56% to 72.05% was confirmed using the transverse spin-spin relaxation time ( T 2 ) distribution and the magnetic resonance imaging (MRI). Experimental results revealed that substantial remobilization and distribution of NAPLs occurred between the macropores ( T 2 greater than 300 ms) and the mesopores (60 ms < T 2 < 300 ms) while the NAPLs in the micropores ( T 2 < 60 ms) remained almost unchanged during 30 FT cycles. The main reason is attributed to the fact that the redistribution rate in micropores is much lower than in macropores and mesopores. Furthermore, the NAPLs content and the number of FT cycles were positively correlated for macropores while negatively correlated for mesopores. For the samples with low NAPLs saturation (e.g., S N =13.56% and 13.56%), the redistribution rate of NAPLs versus FT cycles exhibited an overall linear relationship for macropores and mesopores while a non-liner relationship for micropores. For all pore categories, the increment in S N can cause a remarkable deviation extent. The balance between capillary pressure and freezing-induced pressure was evaluated by the newly introduced dimensionless pressure ratio Δ P , which could help determine the ultimate mobilization and redistribution of NAPLs during FT cycles. Experimental tests suggested that the Δ P was much larger in macropores than in mesopores and micropores. This can explain the dramatic difference in the redistribution rate among different pore categories. This fundamental study is helpful in understanding the mobilization and redistribution mechanisms of NAPLs in cold regions.
研究领域:
环境科学
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地球物理学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2022
·
IF 24.319
Lingxin Peng,Liang Su,Xu Yu,Rongyan Wang,Xiangzhi Cui,Han Tian,Shaowen Cao,Bao Yu Xia,Jianlin Shi
Developing efficient electrocatalysts is of significance for hydrogen production in acid electrolyte. In this work, we report a facile decoration of ruthenium species onto tungsten oxides to construct the Mott-Schottky heterojunction electrocatalyst for hydrogen evolution. The resultant Ru-WO 2.72 hybrid exhibits a superior Ru-based mass activity of 161.6 times higher than that of commercial Ru/C for hydrogen evolution, featuring a Tafel slope of 50 mV dec −1 and 40 mV overpotential at the current density of 10 mA cm −2 . The uniform distribution of Ru species triggers a strong electron transfer across the Ru-WO 2.72 Schottky barrier, resulting in a largely increased local electron density on the active Ru surface. Such electron enrichment induced by the Mott-Schottky effect at the metal-metal oxides interface is responsible for enhanced hydrogen production. This work demonstrates an effective strategy by Mott-Schottky effect to regulate electron distribution, which would evoke more inspiration in designing efficient electrocatalysis and beyond.
研究领域:
电化学
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催化材料科学
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DOI
高影响因子
Nano Research
·
2024
·Vol. 17
·期 6
·4764-4772
·
IF 9.5
Duan Yuhao,Wei Liuxu,Cai Chenyu,Mi Junbao,Cao Fuyuan,Chen Jiaze,Li Xiaolong,Pang Xiujiang,Li Bin,Wang Lei
The chlorine evolution reaction (CER) is a crucial step in the production of chlorine gas and active chlorine by chlor-alkali electrolysis. Currently, the endeavor to fabricate electrodes capable of yielding high current density at minimal overpotential remains a central challenge in advancing the realm of chlorine evolution reactions. Here, we grow TiO 2 and RuO 2 on MXene@carbon cloth (CC) through the favorable affinity and induced deposition effect between the surface functional groups of MXene and the metal. A self-supported electrode (RuTiO 2 /MXene@CC) with strong binding at the electrocatalyst–support interface and weak adhesion at electrocatalyst–bubble interface is constructed. The RuTiO 2 /MXene@CC can reduce the electron density of RuO 2 by regulating the electron redistribution at the heterogeneous interface, thus enhancing the adsorption of Cl − . RuTiO 2 /MXene@CC could achieve a high current density of 1000 mA·cm − 2 at a small overpotential of 220 mV, superior to commercial dimensionally stable anodes (DSA). This study provides a new strategy for constructing efficient CER catalysts at high current density.
研究领域:
电化学
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催化
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材料科学
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纳米技术
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化学工程
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2025
·
IF 14.9
Xuyan Zhou,Zijie Yang,Yinnan Qian,Zhaoyan Luo,Lei Zhang,Qianling Zhang,Chuanxin He,Zhengtang Luo,Xiangzhong Ren
Oxygen evolution reaction (OER) is widely recognized as a bottleneck of water electrolysis. To determine the underlying reaction mechanisms, particularly the relative contribution of the adsorbate evolution mechanism (AEM) and lattice-oxygen participation mechanism (LOM), we conduct a comprehensive investigation combining Density Functional Theory (DFT) calculations and experimental validation. Our theoretical analysis of doped RuO 2 catalysts reveals that heteroatom doping (Ni, Cu, and Zn) induces significant local charge transfer, leading to the increased charge state of Ru and the downshifted d -band center. This, in turn, enables the mechanism switching from the conventional AEM to the more efficient LOM, and finally improves OER activity. We also establish a simple yet powerful descriptor, N e of Ru (representing charge density of Ru sites), which enables accurate prediction of both catalytic activity and stability. Guided by these theoretical predictions, we successfully synthesize a Ni-doped RuO 2 catalyst, which exhibits excellent OER activity and stability in acidic media, achieving an overpotential of just 156 mV and maintaining stability for 4000 h at 10 mA cm −2 , significantly surpassing the performance of the commercial RuO 2 . These findings not only provide fundamental insights into the mechanism-switching behavior in OER catalysis but also offer a practical strategy for designing high-performance, stable electrocatalysts for acidic water electrolysis.
研究领域:
电催化
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材料化学
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物理化学
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能源科学
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纳米材料
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电化学水裂解
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2025
·
IF 8.3
Hongjie Yao,Yufen Liu,Siyuan Yang,Xin Cai,Qiongzhi Gao,Xiaosong Zhou,Xin Li,Shengsen Zhang
Efficient photocatalytic hydrogen evolution is often hindered by sluggish charge transfer within the catalyst and slow interfacial reaction kinetics. Herein, we construct a highly active and durable ternary MoC/MoS 2 /CdS (MMS) photocatalyst by precisely tailoring the MoC/MoS 2 cocatalyst composition and architecture through in-situ vulcanization. The optimized MMS composite delivers a remarkable hydrogen evolution rate of 38.3 mmol g −1 h −1 under simulated solar irradiation, outperforming MoC/CdS and MoS 2 /CdS by factors of 3.4 and 1.8, respectively. Mechanistic studies reveal that MoC acts as an efficient electron reservoir and, together with MoS 2 , constructs a hierarchical charge transfer network, boosting photogenerated electron separation efficiency by 2.7-fold. Moreover, the conductive MoC framework synergizes with the edge active sites of MoS 2 , significantly reducing the overpotential for hydrogen evolution. Density functional theory calculations further demonstrate that the strong interfacial electronic coupling between MoC(110) and MoS 2 (002) facets induces charge redistribution, yielding a low-barrier transfer pathway and optimizing the hydrogen adsorption free energy (ΔG H* = −0.12 eV). This work provides new mechanistic insights and a design strategy for developing high-performance metal sulfide–based synergistic cocatalyst systems.
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产品关联
DOI
高影响因子
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