CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Hongru Jin,Chong Wei,Haozhen Li,Xiaoqiang Li
Internal crystallization is a significant process in the preparation of glass-ceramics (GCs). The glass phase is one of the important factors affecting the internal crystallization process within GCs. In this study, Gd 2 Ti 2 O 7 pyrochlore GCs with different borosilicate glass systems were prepared via an oxide route and consolidated via a cold-pressing and sintering process to be used as waste forms for actinide immobilization. After sintering at 1250°C, it was confirmed that the pyrochlore phase (Gd 2 Ti 2 O 7 ) was the major immobilization phase, while the apatite phase (Gd 9.33 (SiO 4 ) 6 O 2 ) was a minor phase. The influence of glass composition on the minor phase formation and pyrochlore grain growth was also investigated. The content of the minor phase (Gd 9.33 (SiO 4 ) 6 O 2 ) in GCs showed a positive correlation with the content of non-bridging oxygen (NBO) in the glass systems. Meanwhile, the average grain size of the pyrochlore phase also exhibited a positive correlation with the NBO content, highlighting the influence of glass composition on the grain growth process. In addition, static leaching tests confirmed that all GCs exhibited high chemical durability with normalized Gd and Ti leach rates ranging from ∼10 -4 -10 -5 g m -2 d -1 after 28 days. However, preferential leaching of the glass phase was observed in GCs during the leaching tests. Glasses with higher NBO content exhibited more severe alterations from leaching, evidenced by significantly higher leach rates of glass-forming elements such as Si and B. Surface analysis revealed that the GCs surface experienced breakage and peeling, with damage on the glass phase ranging from ∼200 nm to 700 nm.
研究领域:
材料科学
·
核废料管理
✓ 已验证
DOI
高影响因子
CARBON
·
2024
·
IF 10.5
Yu Zhang,Jingde Luan,Panpan Li,Longde Jiang,Haibin Yan,Wengang Liu,Zheng Yan
Water-based homogeneous pre-assembly and thermal polycondensation were used to prepare carbon-doped oxygen-bridged layer-twisted graphite carbon nitride (g-C 3 N 4 ) heterojunction for highly efficient photocatalytic hydrogen evolution (PHE). Despite the narrow band gap of around 0.91 eV, g-C 3 N 4 heterojunction exhibited an excellent hydrogen evolution rate (563.87 μmolg −1 h −1 ) in 30 % methanol/water solution without precious metal assisting catalysts, 36.85 times higher than g-C 3 N 4 . C doping in heptazine ring and bridging O caused the adjacent layer of g-C 3 N 4 to twist by 11° in three-dimensional space. Noticeably, carbon doping in triazine ring was favorable to the establishment of build-in electric field between adjacent layers owing to the delocalized large π bonds . Bridging oxygen acted as a conversion switch for electron storage and transport of photogenerated charge from innerlayer (unmodified layer) with high Fermi level to outlayer (modified layer) with low Fermi level. This work provided an insightful guidance to novel layer-twisted g–C 3 N 4 –based photocatalysts for efficient H 2 production.
研究领域:
材料科学
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能源化学
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理论计算
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2023
·Vol. 28
·期 19
·6879
·
IF 4.6
Tiantian Zhang,Jiacheng Xu,Yan Sun,Shiyu Fang,Zuliang Wu,Erhao Gao,Jiali Zhu,Wei Wang,Shuiliang Yao,Jing Li
Pt-based catalysts exhibit unique catalytic properties in many chemical reactions. In particular, metal–support interactions (MSI) greatly improve catalytic activity. However, the current MSI mechanism between platinum (Pt) and the support is not clear enough. In this paper, the interaction of 1 wt% Pt nanoparticles (NPs) onβ-MnO2in carbon monoxide (CO) oxidation was studied. The Pt onβ-MnO2inhibited CO oxidation below 210 °C but promoted it above 210 °C. A Pt/β-MnO2catalyst contains more Pt4+and less Pt2+. The results of operando DRIFTS-MS show that surface-terminal-type oxygen (M=O) plays an important role in CO oxidation. When the temperature was below 210 °C, Mn=O consumption on Pt/β-MnO2was less thanβ-MnO2due to Pt4+inhibition on CO oxidation. When the temperature was above 210 °C, Pt4+was reduced to Pt2+, and Mn=O consumption due to CO oxidation was greater thanβ-MnO2. The interaction of Pt andβ-MnO2is proposed.Keywords:metal–support interaction;CO oxidation;terminal-type oxygen;bridge-type oxygen;Pt;MnO2
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Frontiers of Environmental Science & Engineering
·
2019
·Vol. 13
·期 2
·1-12
·
IF 3.883
Deng Yuzhou,Peng Shengpan,Liu Haidi,Li Shuangde,Chen Yunfa
Mesoporous TiO 2 was synthesized via nonhydrolytic template-mediated sol-gel route. Catalytic degradation performance upon dichloromethane over as-prepared mesoporous TiO 2 , pure anatase and rutile were investigated respectively. Disproportionation took place over as-made mesoporous TiO 2 and pure anatase under the presence of water. The mechanism of disproportionation was studied by in situ FTIR. The interaction between chloromethoxy species and bridge coordinated methylenes was the key step of disproportionation. Formate species and methoxy groups would be formed and further turned into carbon monoxide and methyl chloride. Anatase (001) played an important role for disproportionation in that water could be dissociated into surface hydroxyl groups on such structure. As a result, the consumed hydroxyl groups would be replenished. In addition, there was another competitive oxidation route governed by free hydroxyl radicals. In this route, chloromethoxy groups would be oxidized into formate species by hydroxyl radicals transfering from the surface of TiO 2 . The latter route would be more favorable at higher temperature.
研究领域:
催化化学
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL RESEARCH
·
2025
·
IF 7.7
Xiuqiong Fu,Qian Wan,Yong Fan,Yimin Zhang,Ruobing Zhang,Zhijie Guo
The preparation of geopolymers from tailings rich in quartz typically requires activation to enhance final strength, though the underlying mechanism remains unclear. Quartz, as a common inert gangue mineral in tailings, was selected as the research subject. Quartz with varying reactivity was prepared through mechanical activation of different particle sizes and used for geopolymer synthesis, aiming to elucidate the strengthening mechanism of activated quartz on geopolymers. When the activation time was identical, quartz particles of different sizes exhibited the same soluble silicon content. However, due to the increased surface-active groups after activation, geopolymers derived from larger quartz particles (5–8 mm) achieved compressive strengths of 57.24–64.73 MPa, while those from smaller particles (0.08–0.12 mm) only reached 43.83–50.42 MPa. After activation, the main active groups on the quartz surface were the Q n (n = 1, 2, 3) structures containing non-bridging oxygens and silicon radicals. The Q 1 and Q 2 structures mainly provide soluble silicon in geopolymerization and have little effect on the strength of the geopolymer. While the Q 3 structure can combine with the geopolymer gel through Si-O-Si bonds, reducing the porosity at the interface between quartz and geopolymer, significantly enhancing the strength of geopolymer. The results indicate that, compared to soluble silicon content of quartz, the content of active groups on its surface is the main factor influencing the performance of geopolymer. For the activation of tailings, increasing the reactivity of their surface is more effective in improving geopolymer strength than enhancing the leaching of soluble silicon and aluminum through overall activation.
研究领域:
材料科学
·
土木工程
·
矿物加工
·
表面化学
·
聚合物科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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