Designing a MOF-based slippery lubricant-infused porous surface with dual functional anti-fouling strategy

Material that resists biofouling adhesion is needed in a complex marine environment, but few of them can combine ultra-low fouling and environmental friendliness. Slippery lubricant-infused porous surface (SLIPS) is such a material, but it lacks the contact-killing ability, which limits its stability and anti-fouling efficiency. Here, we report a metal organic framework (MOF-based) Slippery ionic liquid-infused surface with excellent antifouling performance via synergistic release and contact-killing defense strategy. The dense needle-like MIL-110 array, grown in situ on the aluminum surface, is conducive to the stable stor -age of quaternary ammonium salt (QAS) ionic liquid. Compared to the control group with mature biofilm formed on the surface, SLIPS showed non-fouling performance in a 10-day test and another 21-day test under more challenging conditions. The adsorption amount of lipopolysaccharide (LPS) on SLIPS was 50% lower than that on the aluminum sheet and the aluminum sheet with MIL-110 grown on the surface as the control groups within three hours. The relationship between bacterial adhesion and LPS adsorption indicated that the anti-adhesion performance of SLIPS was mediated by the weak adhesion and easy release property of its surface to extracellular fouling molecules. This study provides the possibility to systematically reveal the antifouling mechanism of SLIPS on bacterial adhesion. (c) 2021 Elsevier Inc. All rights reserved

Tribological properties of alkylated reduced graphene oxide as lubricant additive

As lubricant additive, graphene and/or graphene oxide (GO) has received considerable interest due to its excellent tribological performance. Here, grafting octadecylamine(ODA) onto GO via facile amidation was carried out and hydrazine monohydrate was used as reducing agent to attain ODA-RGO as lubricant additive. The physical, chemical properties and morphologies of ODA-RGO and GO were characterized.Tribological properties were evaluated using a ball-on-plate configuration on a UMT-3 tribometer and then worn surfaces were examined by Scanning electron microscope (SEM), Raman spectra and optical microscope. It was found that ODA-RGO was helpful for lubrication and friction-reduction under the applied load of 10 N. The excellent tribological behavior was contributed to the formation of ODA-RGO protective film which could avoid direct contact between tribological mates. The restacked shape of sheet-like ODA-RGO also plays an important role in friction process

Experimental research on the utilization of gold mine tailings in magnesium potassium phosphate cement

Gold mine tailings (GT) are fine-grained ore processing wastes with a high variety of minerals and metals. Storing large amounts of GT in impoundments results in a waste of resources and in several cases environmental pollution. Magnesium potassium phosphate cement (MKPC) is green-sustainable cement made by magnesia (MgO, M) and KH2PO4, which can be used to effectively immobilize radioactive and hazardous wastes elements through mineralization and microencapsulation. This paper aimed at the utilization of GT in MKPC.GT was incorporated into MKPC through two different pathways, either partially replacing M or the binder (both M and KH2PO4). The influences of GT on MKPC were evaluated through workability, compressive strength, and microstructure. It was found that the partial replacement of M by GT can result in better workability, denser microstructure and higher late-stage compressive strength. The incorporation of GT generates new types of hydrates in the structure. The compressive strength was improved by a factor of 114.94% when an additional 10% M was replaced by GT; when the displacement of GT was 30%, it yielded a compressive strength approaching the basic group. Therefore, the partial replacement of M with GT was suitable to incorporate GT into MKPC in order to achieve the utilization of GT, reduce the cost and improve the mechanical properties of MKPC

One-step fabrication of transparent Barite colloid with dual superhydrophilicity for anti-crude oil fouling and anti-fogging

Hypothesis: Transparent superhydrophilic coatings are very promising in various scenarios. Appropriate fabrication of colloid coatings with superhydrophilicity both in air and under oil would enlarge their application potential in anti-oil fouling and facilitate anti-fogging of transparent surfaces. Experiments: The Barite colloid was obtained from a one-step precipitation method and was transferred onto glasses to prepare transparent coatings with different thicknesses simply by dip-coating. Then, the impact of thickness on wettability and property was studied through the investigation of wettability in various phase, anti-crude oil fouling performance and anti-fogging ability. Findings: Similar surface morphology and roughness of these coatings were achieved and all the coated surfaces showed ultra-hydrophilicity both in air and under oil. Moreover, the hydrophilicity in air and under oil was found to deteriorate with the decrease of coatings' thickness and dual superhydrophilicity could be achieved on thick coatings. More importantly, excellent anti-crude oil fouling property and durable anti-fogging ability were realized on these transparent coatings with dual superhydrophilicity. (c) 2021 Elsevier Inc. All rights reserved

Converting thermally activated delayed fluorescence into hybridized local and charge-transfer via an addition acceptor moiety

High-efficiency blue materials for Organic Light Emitting Diodes (OLEDs) are challenging but urgently needed, especially for solution-processed devices. Herein, based on a model compound of acridine-benzophenone, two blue materials were designed and synthesized, with the additional electron-withdrawing groups benzophenone and pentafluorobenzophenone connected to the acridine donor respectively to prepare BC and BC5F. The solution-processed OLED based on BC showed an emission peak at 486 nm, while the device with BC5F showed the electroluminescent peak at 478 nm. BC featured the thermally active delayed fluorescent (TADF) properties, but BC5F exhibited hybridized local and charge-transferring (HLCT) characteristics. This work showed that linking additional acceptors to the donor side could not only achieve deeper blue emission but also change the luminescent mechanism. Therefore, we provided a new strategy to manipulate the transition between TADF and HLCT

Reduced Graphene Oxide Modified Few-Layer Exfoliated Graphite to Enhance the Stability of the Negative Electrode of a Graphite-Based Potassium Ion Battery

The intercalation of potassium in graphite provides high energy density owing to the low potential of 0.24 V vs. K/K+, thereby making it a promising anode material for potassium ion batteries. However, the high volume expansion (60%) of graphite after potassium intercalation induces significant stress and electrode pulverization. Additionally, the sluggish kinetics of potassium insertion undermine the rate capability of electrodes. Using few-layer exfoliated graphite (EG) as a negative electrode material effectively relieves expansion-induced stress. Unfortunately, the close stacking of ultra-thin two-dimensional EG impedes ion transport. Furthermore, EG with smooth surfaces lacks sites to adsorb K+, which is unfavorable for intercalation reactions. To address these problems, in this study, we designed an rGO/EG/rGO sandwich that coats EG with reduced graphene oxide (rGO). This complex material has two main advantages: (1) its 3D network can effectively prevent EG from stacking and buffer the volumetric variation of EG to improve the cyclic stability of the electrode, and (2) the loose structure and rich functional groups of rGO can also enhance the kinetic of potassium intercalation. Through hydrothermal reduction, GO was coated onto the EG surface and cross-linked to form a 3D network, by which EG stacking could be effectively mitigated. The rGO : EG ratio was precisely controlled by modulating the amount of reactant GO and EG. Transmission electron microscopy and scanning electron microscopy images showed that the rGO was uniformly coated on the EG surface to form a sandwich structure. X-ray diffraction patterns and Raman spectra demonstrated that rGO was physically adsorbed on the EG surface without notable chemical interactions. The EG structure was retained to ensure that its characteristic electrochemical properties were unaffected. Cyclic voltammetry and galvanostatic cycling tests were performed on the complex material with various rGO : EG ratios, exhibiting that rGO : EG = 1 : 1 (w/w) was optimal with a specific capacity of 443 mAh.g(-1) at 50 mAg(-1). Even when operated at a high current density of 800 mA.g(-1), a specific capacity of 190 mAh.g(-1) was achieved, retaining 42.9% of the low-rate capacity, far exceeding those of pristine EG (14.2%) and rGO (27.2%). These results demonstrate that the rGO coating indeed enhanced the kinetics of potassium intercalation and efficiently improved the capacity and rate capability compared to pristine EG. We hope this work sheds light on novel approaches to improving potassium intercalation mechanisms in graphite

Biochar co-doped with nitrogen and boron switching the free radical based peroxydisulfate activation into the electron-transfer dominated nonradical process

In this study, N/B co-doped biochars were employed as metal-free activators of peroxydisulfate (PDS) for tetracycline degradation, more importantly, the roles of dopants and the relative contribution of radical vs nonradical oxidations were comprehensively investigated. Integrating with electron paramagnetic resonance and kinetics calculations, we showed that co-doping N and B into biochars not only boosted the catalytic activity but also switched the radical PDS-activated process into the electron transfer-dominated nonradical process. Compared with pristine biochar/PDS systems (22%), the nonradical contribution of N/B co-doped biochar/PDS systems increased to 59%, exhibiting outstanding stability and selectivity. Galvanic oxidation tests and theoretical simulations unveiled that doped biochars as conductive tunnels accelerate the potential difference-driven electron transfer from the highest occupied molecular orbital of pollutants to the lowest unoccupied molecular orbital of PDS due to the lower energy gap. This study provided new insights into the critical role of heteroatom-doped carbocatalysts in PDS nonradical activation

Mesoporous Ti0.5Cr0.5N for trace H2S detection with excellent long-term stability

Efficient, accurate and reliable detection and monitoring of H2S is of significance in a wide range of areas: industrial production, medical diagnosis, environmental monitoring, and health screening. However the rapid corrosion of commercial platinum-on-carbon (Pt/C) sensing electrodes in the presence of H2S presents a fundamental challenge for fuel cell gas sensors. Herein we report a solution to the issue through the design of a sensing electrode, which is based on Pt supported on mesoporous titanium chromium nitrides (Pt/Ti0.5Cr0.5N). Its desirable characteristics are due to its high electrochemical stability and strong metal-support interactions. The Pt/Ti0.5Cr0.5N-based sensors exhibit a much smaller attenuation (1.3%) in response to H2S than Pt/C-sensor (40%), after 2 months sensing test. Furthermore, the Pt/Ti0.5Cr0.5N-based sensors exhibit negligible cross response to other interfering gases compared with hydrogen sulfide. Results of density functional theory calculation also verify the excellent long-term stability and selectivity of the gas sensor. Our work hence points to a new sensing electrode system that offers a combination of high performance and stability for fuel-cell gas sensors

High microwave absorption performance in Nd-substituted BaM/GO through sol-gel and high energy ball milling process

In this paper, a series of compound materials with different proportions of rare earth neodymium (Nd) doped M-type barium ferrite (BaM) and the mixture Nd-BaM with graphene oxide (GO) are prepared through the sol-gel method and high-energy ball milling route. The surface morphology, composition and electromagnetic properties of those materials are analyzed through XRD, SEM, TG, Raman and the vector network analyzer. It is found that the Nd-BaM particle is adhered on the surface of GO with the nanometer size. The electromagnetic performance can be severely affected by the doping amounts of Nd and the blending amounts of GO. Moreover, the microwave absorption performance of the compounds is studied in the frequency range of 2-18 GHz. For Nd-0.15-BaM/3%GO, the minimum reflection loss is - 82.07 dB at 12.65 GHz and the scope of the effective absorption band is 6.08 GHz with a thickness of 2 mm. Because of its good impedance matching, the interface polarization and electron polarization between Nd-BaM and GO, the electromagnetic wave occurs multiple reflection in this material. Compared with pure BaM or BaM/GO, the Nd substituted BaM/GO has excellent microwave absorption performance, which has a certain prospect in the microwave absorbing field. (C) 2021 Published by Elsevier B.V