Institutional Repository of Ningbo Institute of Material Technology & Engineering, CAS
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Dual-phase metal nitrides as highly efficient co-catalysts for photocatalytic hydrogen evolution
No full textLow solar-to-fuel conversion in conventional semiconductor-based photocatalysts limits their commercial applications. Searching for highly efficient cost-effective co-catalysts is desirable for the development of artificial photosynthesis systems. In this work, we report a simple yet efficient electrostatic self-assembly process to synthesize one-dimensional Co4N-WNx-CdS composites for visible light-driven hydrogen evolution in pure water. Biphasic transition metal nitrides Co4N-WNx with high conductivity and enriched active sites leads to multi-level electrons transfer and lower over-potential for hydrogen production. Co4N-WNx-CdS composite, with optimized wt%, exhibits the highest rate of photocatalytic hydrogen evolution (14.42 mmol g(-1)h(-1)) under vacuum condition. This rate is similar to 8 times higher than that of the Pt-CdS composite (1.78 mmol g(-1)h(-1))
The effects of stress on corrosion behavior of SIMP martensitic steel in static liquid lead-bismuth eutectic
No full textAs for a newly developed tempered martensitic steel, SIMP with 1.4 wt.% Si, used in the Chinese Initiative Accelerator Driven System (CiADS), so it is worth investigating the stress corrosion property of SIMP steel in liquid lead-bismuth eutectic at the system operating temperature. The compatibility of the structural materials with the proposed operational conditions was investigated by performing corrosion-mechanical testing. The stress corrosion was performed in static lead-bismuth eutectic at 300 degrees C, 450 degrees C, and 500 degrees C with different loading stresses. The effect of stress on corrosion rate at different temperatures was investigated by scanning electron microscopy and transmission electron microscopy. The testing of SIMP steel showed that the corrosion rate in the presence of LBE was strongly temperature-dependent. At 300 degrees C, only a very thin oxide scale was formed which inhibits the Pb and O from penetrating inside matrix steel, and hence keeps it ductile (no crack). On the other hand, at 450 and 500 degrees C, the stress can significantly enhance the corrosion rate at 450 degrees C and 500 degrees C, but not at 300 degrees C. Reasons are investigated and discussed based on the available space model
Superhydrophobic and Self-Healing Mg-Al Layered Double Hydroxide/Silane Composite Coatings on the Mg Alloy Surface with a Long-Term Anti-corrosion Lifetime
No full textBoth a superhydrophobic structure and layered double hydroxide (LDH) coating were effective to improve the corrosion resistance of alloys. In this study, a superhydrophobic composite coating based on LDHs was constructed on Mg alloy by laser treatment, in situ growth of Mg-Al LDHs, and modification with octadecyl-trimethoxy-silane (OTS). The so-obtained composite coating was coded as L-LDHs-OTS, where L stands for laser treatment. Results showed that the L-LDHs-OTS composite coating presented the best anti-corrosion performance and the corrosion current density was reduced by about 5 orders of magnitude compared with that of the Mg alloy substrate. The excellent corrosion resistance was related to the superhydrophobicity of the composite coating, the compactness and ion-exchange capacity of the LDH layer, and the dense Si-O-Si network within the OTS layer. Moreover, the L-LDHs-OTS composite coating was still effective after 20 days of immersion tests, showing good long-term corrosion resistance due to the existence of hydrophobicity of the composite coating and the self-healing ability of LDHs
Ultrasound-Mediated Cavitation Enhances EGFR-Targeting PLGA-PEG Nano-Micelle Delivery for Triple-Negative Breast Cancer Treatment
No full textTriple-negative breast cancer (TNBC) is highly recurring and metastatic breast cancer with overexpressing epidermal growth factor receptor (EGFR). Herein, a series of in vitro and in vivo analyses were used to explore the therapeutic effect of EGFR-targeting nano-micelles (PLGAPEG/DOX@anti-EGFR) combined with ultrasound-mediated cavitation (UMC). The prepared nanomicelle drug carriers have good biocompatibility and can greatly increase the drug accumulation in tumor regions, thereby reducing off-target toxicity while enhancing anti-tumor efficacy. Moreover, an in vivo analysis of the practical utility of this treatment modality was conducted by using SonoVueTM microbubbles to achieve cavitation under different power intensity levels, with an ultrasonic power intensity of 0.5 W/cm2 maximizing the intra-tumoral blood perfusion. Relative to PLGA-PEG@DOX/anti-EGFR nano-micelles treatment alone, the combination with UMC was better able to suppress tumor growth even at low concentrations. As such, combining actively targeted drug-carrier molecules with UMC represents an effective approach to enhancing therapeutic efficacy while reducing the adverse, systemic effects associated with DOX and other chemotherapeutic drugs, and it can be considered as a promising clinical prospect in the treatment of TNBC
Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation
No full textIn this work, we report the same trends for the contact potential difference measured by Kelvin probe force microscopy and the effective carrier lifetime on crystalline silicon (c-Si) wafers passivated by AlOx layers of different thicknesses and submitted to annealing under various conditions. The changes in contact potential difference values and in the effective carrier lifetimes of the wafers are discussed in view of structural changes of the c-Si/SiO2/AlOx interface thanks to high resolution transmission electron microscopy. Indeed, we observed the presence of a crystalline silicon oxide interfacial layer in as-deposited (200 degrees C) AlOx, and a phase transformation from crystalline to amorphous silicon oxide when they were annealed in vacuum at 300 degrees C
Self-powered ultraviolet MSM photodetectors with high responsivity enabled by a lateral n(+)/n(-) homojunction from opposite polarity domains
No full textWe report aGaN-based self-powered metal-semiconductor-metal (MSM)-type ultraviolet (UV) photodetector (PD) by employing a lateral polarity structure (LPS) grown on the sapphire substrate. An in-plane internal electric field and different Schottky barrier heights at a metal/semiconductor interface lead to efficient carrier separation and self-powered UV detection. A dark current of 6.8 nA/cm(2) and detectivity of 1.0 x 10(12) Jones were obtained without applied bias. A high photo-to-dark current ratio of 1.2 x 10(4) and peak responsivity of 933.7 mA/W were achieved for the lateral polarity structure-photodetector (LPS-PD) under 10 V. The enhanced performance of the LPS-PD was ascribed to the polarization-induced carrier separation as demonstrated by the lateral band diagram. (C) 2021 Optical Society of Americ
V2CTx and Ti3C2Tx MXenes Nanosheets for Gas Sensing
No full textIn this paper, the performance and fundamental mechanisms on gas sensing of V2CTx and Ti3C2Tx MXenes were investigated. The MXenes nanosheets with the same chemical composition can show positive or negative response to the same gas due to the change of surface chemistry, which, in turn, is affected by the etching solution to make the samples. The residual Li or Na atoms on the surface of MXenes have a weak impact on the gas sensing performance; however, the ratio of Cl/F has a strong impact. V2CTx made in HF showed positive/zero response to the eight gases tested in this paper and had excellent sensing performance to methane. However, V2CTx made in LiF+HCI showed negative/zero response, while that made in NaF+HCl displayed positive response only to formaldehyde. Ti3C2Tx made in NaF+HCl showed a positive response to all detected gases while that made in ZnCl2 had better gas detection ability but showed a negative response to ammonia, triethylamine, and toluene. On the basis of the theoretical simulations, the structure-sensitive sensing behavior of MXenes as gas sensors is mainly ascribed to the structure-dependent electron transmission mechanism upon adsorbed gas molecule. This study is significant to the application of MXene sensors for designing specific gases
Fracture mechanics of methane clathrate hydrates
No full textFundamental mechanics of gas hydrates is of importance to evaluating geomechanical and geotechnical properties of gas hydrate deposits, but it remains largely unexplored yet due to insufficient direct experimental techniques and high-quality of gas hydrate samples. Here, classic molecular dynamic (MD) simulations are used to study the fracture mechanics of three main methane clathrate hydrates of sI, sH and sH types. The results show that the mechanical properties of those three methane clathrate hydrates are intrinsically different and are degraded by the presence of nanocracks. They show brittle facture and different fracture toughness. In terms of energy release rate, they are ranked as sH> sI > sH. Moreover, the three methane clathrate hydrates with nanocracks can be explained by a modified Griffith criterion. Moreover, it is intriguingly identified tip amorphization during the crack propagation process of the three methane clathrate hydrates, and sH methane clathrate hydrate with specific nanocrack exhibits slower crack propagation than other two methane clathrate hydrates
Dinitrogen Activation by Uranium Complex
No full textDinitrogen is the most abundant gas in the air (approximately 78% of the total air volume). which is a precious resource endowed by nature. How to make use of dinitrogen and transform it into useful nitrogenous compounds is important for humans and sustainable development of society. Dinitrogen activation. as a very important research field. has always been a major challenge. At present. low valent uranium complexes exhibit excellent performance in the small molecule activation. This review mainly introduces and summarizes the application of uranium complexes in dinitrogen activation and transformation. and the prospect of this field is prognosticated
Compendious evaluation of groundwater in parts of Asaba, Nigeria for agricultural sustainability
No full textThe hydrogeochemical evolution and irrigation suitability assessment of groundwater in selected parts of Asaba, Nigeria, has been conducted. The purpose of this study was to ascertain the hydrogeochemical relations and interactions of groundwater with rocks, and also assess the usefulness of the groundwater for irrigation purpose. Twenty (20) groundwater samples were analyzed for physical and chemical compositions. All tested water parameters were within the WHO (2017) recommended standard for drinking water except for Fe2+, which showed worrisome amount. Furthermore, hydrogeochemical plot with Piper trilinear diagram showed that groundwater samples in the study area is sodium bicarbonate and mixed water types and Schoeller semi-logarithmic plot showed an ionic trend of HCO3- + CO32- > Na+ + K+ > Mg2+ > Ca2+ > SO42- > Cl-. Langelier and Ludwig diagrams reveal that the hydrogeochemical evolution trend is towards the Cl--SO42--Na+ + K+ compositions. The indices of Chloro-Alkaline (CA) and Index Base Exchange (IBE) shows that the CA1 and CA2 are negative, implying that there is an exchange between (Na+ + K+) in the groundwater and (Ca2+ + Mg2+) of rocks. For the irrigation suitability, the SAR, %Na+, RSC, and MR ranged between 0.5 to1.49, 44.6 to 81.5, 0.48 to 2.02, and 9.61% to 98.8%, respectively. These imply that most of the tested groundwater could be used for irrigation purposes, while some are considered unfit for such. Therefore, regular routine assessment of the groundwater is recommended to ascertain its suitability for agriculture (irrigation) and domestic uses