POWDER METALLURGY
·
2019
·
IF 1.149
Jiaxin Li,Yuhong Chen,Yongquan Li,Zhangjun Bai,Kang Wang
Alloys with composition of Ta-10 wt.% W and Ta-10 wt.% W-6 wt.% Al, respectively, were prepared by the hot-press sintering process. The oxidation behaviour at 900°C and 1000°C was studied. The oxidation weight gain curves of the Ta–10%W alloy followed the linear law and the final oxidation product was Ta2O5 solid solution. Meanwhile, due to the addition of Al, the oxidation weight gain curves of the Ta–10%W–6%Al alloy followed the parabolic law. The final oxidation products at 900°C formed a dense outer layer Al2O3 and an inner layer. However, after being oxidised at 1000°C, the oxidation products included Al2O3, AlTaO4 and Ta22W4O67. Since the dense Al2O3 oxide film was consumed by the generation of AlTaO4, the inward diffusion of oxygen cannot be prevented. The oxidation resistance degraded at 1000°C. The addition of Al significantly improved the oxidation resistance of the Ta-W-based alloy system.
研究领域:
材料科学
·
金属学
✓ 已验证
产品关联
DOI
高影响因子
Energy Storage Materials
·
2017
·
IF 0
Liping Wang,Lei Zhang,Qingji Wang,Wenjun Li,Bo Wu,Weishang Jia,Yuehui Wang,Jingze Li,Hong Li
Lithium metal is a Holy Grail anode for high energy density lithium ion batteries . While, its high chemical reactivity and high tendency to form dendrites hinder its wide applications. Here, in this study, we stabilize lithium metal by engineering an artificial SEI layer, namely fabricating a conformal nano-meter thickness amorphous Al 2 O 3 thin film via magnetron sputtering technique on its surface. The obtained Al 2 O 3 modified Li metals present robust chemical surface stability and effectively restrain the dendrite growth. 20 nm-thick Al 2 O 3 film modified lithium metal in an all-solid-state battery Li/PEO-LiTFSI/Li ensures a cycle life of 660 h at a current density of 0.1 mA/cm 2 . Contradicting to a traditional belief of lithium plating at the current collector side via crossing the Al 2 O 3 film, it directly plates on the Al 2 O 3 film next to the separator side. Al 2 O 3 film plays a crucial role as a “surfactant” in inducing a layer-by-layer film growth mode.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
SOLID STATE PHENOMENA
·
2018
·
IF 0
Min Wang,Zi Yuan Wang,Ya Jie Yuan,Wei Pan
The 8 wt.% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) are widely used to protect hot superalloy components of gas turbine and jet engine. However, Cracks and pores in the 8YSZ coating would accelerate the oxidation of the bondcoat alloy and the corrosion of 8YSZ topcoat by molten salts and finally result in permanent failure of the TBCs. Hence, in this work, a sol-gel spin-coating method was employed to prepare a dense α-Al2O3 film on the surface of air-plasma-sprayed 8YSZ coatings, in order to block the paths of cracks and pores while keeping the stress tolerance of 8YSZ coatings. The influences of the polyvinylpyrrolidone (PVP) and alumina content of the sol on the microstructure of the α-Al2O3 film were investigated. It is found that a sol with PVP addition amount of 50 mg/mL and alumina solid content of 10% let to the achievement of a compact α-Al2O3 film. The positive results in this work would inspire more efforts to prepare dense films on TBCs and therefore improve their performance under service conditions.
研究领域:
材料科学
·
表面工程
✓ 已验证
产品关联
DOI
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Siyuan Hu,Mingzhen Huang,Jingru Li,Jinxin He,Kaiji Xu,Xiaoping Rao,Dongren Cai,Guowu Zhan
Herein, atomic layer deposition (ALD)-Al 2 O 3 films were applied as a medium to modulate the electronic states of the supported Pt. Based on the sacrificial template of ZIF-67, the ternary Co 3 O 4 /Pt/Al 2 O 3 catalyst exhibited better performance in catalytic CO oxidation than the binary Co 3 O 4 /Pt catalyst. Both experimental and calculation results indicate the existence of charge transport between the Pt and the ALD-Al 2 O 3 films, leading to electron-rich Pt, enhanced O 2 affinity, and reduced activation energy. Interestingly, the oxidation resistance of Pt nanoparticles was visualized when annealing Co 3 O 4 /Pt/Al 2 O 3 catalyst at high temperatures. Mechanism studies indicate the typical LH mechanism occurred in CO oxidation , showing that the co-adsorbed CO and O 2 could be converted to carbonate-type *OCOO intermediates via low energy barriers. At low temperatures, CO 2 was mainly produced by the lattice oxygen-mediated M-vK mechanism based on isotope labeling experiments. Our findings provide an alternative way to regulate the electronic states of noble metals by the ALD technique.
研究领域:
催化化学
·
材料科学
·
理论计算
✓ 已验证
产品关联
DOI
高影响因子
NANOTECHNOLOGY
·
2024
·Vol. 35
·期 31
·315704
·
IF 2.9
Jiajun Li,Xiaojun Ye,Chi Yan,Cui Liu,Xiao Yuan,Hongbo Li,Jiahui Xu,Hua Tong
The polar channels formed by the curing of waterborne anticorrosive coatings compromise their water resistance, leading to coating degradation and metal corrosion. To enhance the anticorrosive performance of waterborne coatings, this study proposed a novel method of depositing ultrathin Al2O3 films on the surface of waterborne epoxy coatings by atomic layer deposition, a technique that can modify the surface properties of polymer materials by depositing functional films. The Al2O3-modified coatings exhibited improved sealing and barrier properties by closing the polar channels and surface defects and cracks. The surface structure and morphology of the modified coatings were characterized by x-ray photoelectron spectroscopy and scanning electron microscopy. The hydrophilicity and corrosion resistance of the modified coatings were evaluated by water contact angle measurement, Tafel polarization curve, and electrochemical impedance spectroscopy. The results indicated that the water contact angle of the Al2O3-modified coating increased by 48° compared to the unmodified coating, and the protection efficiency of the modified coating reached 99.81%. The Al2O3-modified coating demonstrated high anticorrosive efficiency and potential applications for metal anticorrosion in harsh marine environments.
研究领域:
材料科学
·
腐蚀与防护
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Catalysis
·
2024
·
IF 11.3
Yanmei Cai,Cunbiao Lin,Xingwen Cha,Yiling Wu,Xiaoping Rao,Kok Bing Tan,Dongren Cai,Gui-Lin Zhuang,Guowu Zhan
The supported Ni/In2O3 catalysts are of great interest in CO2 hydrogenation, but the formation of the In0 or Ni–In alloy phases due to over-reduction would lead to rapid catalyst deactivation. Herein, thin Al2O3 films were deposited on the Ni/In2O3 surface by atomic layer deposition (ALD) as an antireduction agent, which enables the In2O3 catalyst to maintain a significant abundance of active In3+ species even during high-temperature H2 treatment (400 °C, 2 h), thereby effectively resisting the deactivation caused by over-reduction of In2O3. Various characterization methods confirm the antiover-reduction effect of ALD-Al2O3 films, namely, inhibiting the formation of In0 and In3Ni2 alloys during high-temperature H2 treatment and facilitating the reoxidation of low-valence In to form the active In2O3–x phase in the presence of a CO2 atmosphere. As treated with H2 at 400 °C, the 5Al2O3/Ni/In2O3-R400 catalyst exhibited an STYMeOH of 7.39 gMeOH h–1gNi–1 and a methanol selectivity of 64% (reaction conditions: 3 MPa, 300 °C, and 12,000 mL gcat–1h–1). Particularly, the STYMeOH increased by 11.5 times as compared with that of the Ni/In2O3-R400 catalyst without coating the ALD-Al2O3 layer (0.59 gMeOH h–1gNi–1). Density functional theory (DFT) calculations validate the effectiveness of specific charge transfer tendencies in suppressing the over-reduction of high-valence In species. Through the analysis of the crystal orbital Hamilton population (COHP) and projected density of states (PDOS) electronic structures of the adsorbate species, the Al2O3/Ni/In2O3 catalyst is shown to significantly enhance CO2 activation and further catalytic reactions. Accordingly, this study unveils the deactivation mechanism of In2O3-based catalysts due to over-reduction and provides a method to regulate their reduction level by depositing ALD-Al2O3 films on the In2O3-based catalysts.
研究领域:
催化化学
·
材料科学
·
理论计算化学
✓ 已验证
产品关联
DOI
高影响因子
Materials Research Express
·
2021
·Vol. 8
·期 5
·055504
·
IF 1.62
Fengpo Yan,Hao Zhang,Yu Zhang,Fugui Yang
0.3 mol% platinum loaded g-C3N4 sample was prepared by photoreduction method to study the long-term stability of photocatalysts. For the first time, we have discovered the oriented attachment (OA) mechanism growth of Pt nanoparticles on g-C3N4 solid surface, which is completely different from Ostwald ripening (OR) or particle migration and coalescence (PMC) that previously reported. The Pt nanoparticles perform Brownian motion on the surface of g-C3N4 support under the collision of liquid molecules, then two or more nanoparticles attach together via the crystallographic orientation to construct larger ones. Al2O3 film prepared by atomic layer depositon was introduced to inhibit the Brownian motion of Pt nanoparticles. It is found that as the increase of the Al2O3 growth cycles, the photocatalytic hydrogen production of Pt/g-C3N4 coated by Al2O3 increase from 1.14 mmolg−1h−1 to 2.08 mmolg−1h−1 and then decrease to 1.4 mmolg−1h−1, and the apparent quantum efficiency (QE) also increase from 1.2% to 2.1% and then decrease to 1.4%. Meanwhile, the long-term stability of photocatalyst always increases. This work has revealed new pathway of photocatalytic nanoparticle growth on solid surface and proposed the method to prevent it.
研究领域:
材料科学
·
光催化
✓ 已验证
DOI
高影响因子
ACS Applied Nano Materials
·
2022
·
IF 6.14
Yujia Yuan,Zhongliang Huang,Siyuan Hu,Dongren Cai,Guowu Zhan
In the field of catalysis, nanoreactors with spatially restricted effects play a critical role to enhance the production efficiency of a variety of reactions. In this contribution, we used ZIF-67 nanocubes (size of 140 nm) as a template and conformally deposited Al2O3 thin films by the atomic layer deposition (ALD) technique, wherein Pt nanoparticles (Pt NPs) as active sites were loaded on either the inside or outside of the Al2O3 films. Notably, it was found that the water treatment of the nanoreactors was critical to the enhanced catalytic CO oxidation performance with substantially decreased T100 (temperature to achieve 100% conversion). Various characterization results indicated the successful synthesis of yolk–shell structured ZIF-67/Pt@10Al2O3-W catalyst with excellent CO oxidation activity and good long-term stability. In addition, in situ diffuse reflectance infrared Fourier transform spectroscopy was used to explore the catalytic oxidation process, and the results revealed that the reason for the superior CO catalytic activity of the designed nanoreactors was ascribed to the moderate CO surface coverage provided by the Al2O3 films and the activated oxygen species. In summary, this work provides some insights into the preparation of metal–organic framework-based nanoreactors using ALD-assisted methods.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Zhen Zhang,Chi Yan,Jiahui Xu,Cui Liu,Xiaojun Ye,Xiao Yuan,Hongbo Li
Atomic layer deposition (ALD) has drawn considerable attention recently for depositing functional films on polymers. However, most polymers are inert and thermally fragile, thus posing many challenges during deposition. This study presents a novel strategy for ALD of an ultrathin Al 2 O 3 film on alkali-treated polyethylene terephthalate (PET) via polydopamine (PDA) modification. The tightly adherent PDA layer exhibited numerous robust active sites (phenolic hydroxyl groups), which are highly desirable for precursor chemisorption during ALD. The modification process was systematically characterized. The PET substrate showed many active sites and a smooth surface after 24 h of PDA deposition. The island growth mode was found during the ALD of an Al 2 O 3 film on the samples. The PDA layer absorbed a large quantity of the precursor (trimethylaluminum [TMA]) during the initial deposition, contributing to the early nucleation and continuous growth of the Al 2 O 3 film. In addition, the presence of the PDA layer narrowed the region of TMA infiltration into the PET, resulting in the formation of a conformal film on the surface. Transmission electron microscopy indicated that an Al 2 O 3 film with a thickness of about 10 nm was formed on the PDA-modified PET substrate after 100 ALD cycles, and exhibited excellent water vapor blocking characteristics. These findings suggest that the added PDA layer has tremendous potential to act as a bonding layer between polymers and ALD functional films.
研究领域:
材料科学
·
表面化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）