Surface Functional Properties Research Articles

Surface Chemistry of Metal Phosphide Nanocrystals

Semiconducting and metallic metal phosphide nanocrystals have gained increased attention in the materials science and engineering community due to their demonstrated and theoretical promise in both emissive and catalytic applications. Central to realizing the full potential of nanoscale metal phosphides is a thorough understanding of their surfaces and how surface chemistry impacts their function. In this review, we document what is known about the surface chemistry of metal phosphide nanocrystals, including both as synthesized and postsynthetically modified species, and draw a connection between surface chemistry and functional properties. This survey is intended to provide a comprehensive view of metal phosphide nanocrystal surface chemistry and how it differs across the families of phosphide materials. A clear distinction emerges between the semiconducting and metallic phosphides from both a synthetic and applied standpoint. We seek to expose key knowledge gaps and targets for further scientific and technological development.

Metal Organic Framework Functionalized Textiles as Protective Clothing for the Detection and Detoxification of Chemical Warfare Agents—A Review

Chemical warfare agents (CWAs) have been listed as lethal weapons of mass destruction due to their extreme toxicity and devastating effects. Detection and detoxification are essential to protect ourselves from such acutely perilous agents and have therefore generated a great deal of research interest. In this context, studies show that adsorbents such as activated carbon, metal oxides, and metal organic frameworks (MOFs) are active materials for the effective degradation of CWAs. Among them, MOFs are preferred because of their large surface area, tunable porosity, and catalytic, functional, and chemical stability properties. With this background, we comprehensively review the historical purview of the utility of CWAs, the potency of various CWAs, and their toxic profiles. Further, we discuss the research strategies reported to synthesize MOFs of desirable characteristics by tuning the synthesis parameters such as solvents, temperature, guest molecules, and organic ligands. Specifically, we highlight the multifarious studies of the impregnation of MOFs onto fibers/textiles as self-protecting fabrics using different techniques. Finally, we enumerate the challenges in developing MOFs-incorporated textiles and their functionalization toward the detection and detoxification of CWAs. As a future perspective, further requirements and possibilities of using MOF-modified textiles as wearable electronic devices for the detection and detoxification of CWAs have also been addressed.

Enhanced electrochemical detection of dopamine by graphene oxide/tungsten trioxide nanocomposite

Dopamine plays a vital role in neurotransmission and dopamine level detection in body fluid is very essential for diagnosis of neurological diseases. Finding a novel material, which enhances the electrochemical detection of dopamine is necessary in the present scenario. The Graphene oxide/tungsten trioxide (GO/WO3) nanocomposite were prepared by two-step procedure; modified Hummer's method for GO synthesis, followed by co-precipitation method for the preparation of WO3 with GO. The structural, chemical compositional and surface functional properties of as-synthesized GO/WO3 composite were systematically characterized. The WO3 nanocube shaped particles with an average diameter of 100–200 nm, completely covered the GO surface, during the in-situ growth process. Glassy carbon electrode (GCE) modified with prepared GO/WO3 nanocomposite was used as working electrode and analysed its selective and sensitive detection of dopamine by means of electrochemical measurements. The chronoamperometric results revealed that, GCE has wide linear range of (0.3 μM–1245 μM) of dopamine detection with outstanding selective performances. The limit of detection to 0.306 μM and sensitivity 0.392 μA μM−1cm−1 of electrode was calculated. The as-prepared GCE towards the detection of dopamine was tested in real samples (human urine), the measured results established the great dopamine sensing abilities with high selectivity and good stability in real samples.

Controllable preparation of boron nitride quantum dots with small size and strong blue photoluminescence

As a new type of quantum dots (QDs), boron nitride QDs (BNQDs), show promising potentials in disease diagnosis, fluorescence imaging and bio-sensing due to its good biocompatibility, low cytotoxicity and excellent photoluminescence performance. However, there are still challenges in preparing BNQDs with uniform and small size. In this paper, the BNQDs with uniform and small size have been prepared through a hydrothermal process with the exfoliated hexagonal boron nitride nanosheets (h-BNNSs) as precursor. The as-prepared BNQDs were characterized by transmission electron microscope (TEM), high-resolution TEM, fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis and photoluminescence spectra (PL) for morphology, surface functional groups, element composition and optical properties. The as-prepared BNQDs have uniform particle size distribution with an average lateral size of 1.65 nm, and a PL quantum yield of 2.49 %. In addition, the as-prepared BNQDs exhibit strong blue fluorescence under UV-vis (365 nm) irradiation and nanosecond luminescent decay. Furthermore, the effect of preparation parameters on the fluorescence performance of BNQDs was investigated which provides an optimal condition for the preparation of BNQDs with excellent fluorescence performance. Together with other advantages, such as excellent physical/chemical properties, good biocompatibility and low cytotoxicity, the as-prepared BNQDs have great potentials in medical diagnosis, biosensing, photoelectric devices and other fields in the future.

Enhancement of fluorescence and magnetic properties of CeF3:RE3+ (Tb, Gd) nanoparticles via multi-band UV excitation and Li doping regulation

In this study, hydrothermal synthesis of CeF3: Tb, Gd nanoparticles doped with Li+ alkali metal ions were demonstrated using introduction of Li+ ions through LiNO3 nitrate. These nanoparticles have dual properties of magnetic fluorescence. X-ray diffraction, Fourier transform infrared spectrometer, XPS and photoluminescence spectra, and vibrating sample magnetometry were used to characterize structural properties, surface functional groups, fluorescence, and magnetic properties of these particles. Results show that CeF3: Tb, Gd nanoparticles exhibit bright green light emission under excitation at 258 nm and 378 nm ultraviolet band. Through the modification of Li+ ions, luminous intensity of green light is further improved. Energy transfer between rare earth ions was investigated via photoluminescence spectroscopy. This work demonstrates potential applications of Li doped CeF3: Tb, Gd nanoparticles as photomagnetic dual-functional materials in fields of biological imaging, solid state lighting, and magnetic biological separation.

Polydopamine nanospheres coated with bovine serum albumin permit enhanced cell differentiation: fundamental mechanism and practical application for protein coating formation.

Protein coating is a strategy for modifying and improving the surface functional properties of nanomaterials. However, the underlying mechanism behind protein coating formation, which is essential for its practical applications, remains largely unknown. Herein, we investigate the fundamental molecular mechanism of protein coating formation. Polydopamine nanospheres (PDANS) coated with bovine serum albumin (BSA) are examined in this study due to their wide biomedical potential. Our results demonstrate that BSAs can flexibly bind to PDANS and maintain their structural dynamicity. Our findings unveil that regular structure formation arises from BSAs lateral interactions via electrostatic forces. Notably, the protein coating modified PDANS surface enhances cell adhesion and proliferation as well as osteogenic differentiation. Such an enhancement is attributed to complementary surface properties provided by the dynamic PDANS-BSA complex and regular structure caused by BSA-BSA interactions in protein coating formation. This study provides a fundamental understanding of the molecular mechanism of protein coating formation, which facilitates the further development of functional protein-coated nanomaterials and guides the bioengineering decision making for biomedical applications, especially in bone tissue engineering.

Biomass-Derived Porous Carbons Derived from Soybean Residues for High Performance Solid State Supercapacitors.

A series of heteroatom-containing porous carbons with high surface area and hierarchical porosity were successfully prepared by hydrothermal, chemical activation, and carbonization processes from soybean residues. The initial concentration of soybean residues has a significant impact on the textural and surface functional properties of the obtained biomass-derived porous carbons (BDPCs). SRAC5 sample with a BET surface area of 1945 m2 g−1 and a wide micro/mesopore size distribution, nitrogen content of 3.8 at %, and oxygen content of 15.8 at % presents the best electrochemical performance, reaching 489 F g−1 at 1 A g−1 in 6 M LiNO3 aqueous solution. A solid-state symmetric supercapacitor (SSC) device delivers a specific capacitance of 123 F g−1 at 1 A g−1 and a high energy density of 68.2 Wh kg−1 at a power density of 1 kW kg−1 with a wide voltage window of 2.0 V and maintains good cycling stability of 89.9% capacitance retention at 2A g−1 (over 5000 cycles). The outstanding electrochemical performances are ascribed to the synergistic effects of the high specific surface area, appropriate pore distribution, favorable heteroatom functional groups, and suitable electrolyte, which facilitates electrical double-layer and pseudocapacitive mechanisms for power and energy storage, respectively.

The multi-scale analysis of ceramic surface topography created in abrasive machining process

The paper looks at the issues related to the shaping technology of the parts made of ceramic materials and at the influence that machined surface topography has on surface functional properties. The mono- and polycrystalline ceramic parts were shaped in the four treatments of finishing process. The studies of surface topography were performed using three measurement instruments: interference microscope, scanning electron microscope, and atomic force microscope. It was noticed that multi-scale analysis of surface topography allows for obtaining a complementary and detailed overview of changes that ceramic parts undergo during abrasive machining process. The characteristics of the machined surface created in finishing operations were prepared based on the quantitative and qualitative descriptions. Parametric analysis of surface texture allowed for assessing the quality and changes of the machined surface in the technological process. During the non-parametric analysis, surface views after each abrasive machining treatment showed different kinds of surface defects (cracks, crumbles, dents or scratches) which could play an important role in the operation process, i.e. generating various wear mechanisms.

Innovating protectives gears for frontline health professionals in the COVID-19 pandemic at a low resource setting

We communicate briefly about the innovation of protective gear (such as Hazmat suit) and respirator mask that can be used by health care professionals as mouth and nose protection tools against the penetration of the microscopic particles containing highly contagious species into the body. As a research and development support to the local entrepreneurs willing to come up with innovative products, the structural and some surface functional properties of the polymeric materials available in local market were analyzed in comparison to the commercially available gears and masks. It has been found that the respirator masks, equivalent in structure and functional properties as the common commercially available protective gears could be developed that can be used by front-line health professionals for protection against contagious environment. The research has paved way to manufacture highly useful health care products at significantly lower costs under low resource setting.

Improved Surface Functional and Photocatalytic Properties of Hybrid ZnO-MoS2-Deposited Membrane for Photocatalysis-Assisted Dye Filtration.

The synergistic mechanism of photocatalytic-assisted dye degradation has been demonstrated using a hybrid ZnO-MoS2-deposited photocatalytic membrane (PCM). Few layers of MoS2 sheets were produced using the facile and efficient surfactant-assisted liquid-phase exfoliation method. In this process, hydrophilic moieties of an anionic surfactant were adsorbed on the surface of MoS2, which aided exfoliation and promoted a stable dispersion due to the higher negative zeta potential of the exfoliated MoS2 sheets. Further, the decoration of ZnO on the exfoliated MoS2 sheets offered a bandgap energy reduction to about 2.77 eV, thus achieving an 87.12% degradation of methylene blue (MB) dye within 15 min of near UV-A irradiation (365 nm), as compared with pristine ZnO achieving only 56.89%. The photocatalysis-enhanced membrane filtration studies on the ZnO-MoS2 PCM showed a complete removal of MB dye (~99.95%). The UV-assisted dye degradation on the ZnO-MoS2 PCM offered a reduced membrane resistance, with the permeate flux gradually improving with the increase in the UV-irradiation time. The regeneration of the active ZnO-MoS2 layer also proved to be quite efficient with no compromise in the dye removal efficiency.

Graphite oxide nanocoatings as a sustaibale route to extend the applicability of biopolymer-based film

In this work, the Layer-by-Layer assembly of multilayered coatings comprising graphite oxide (GO) in combination with either chitosan or branched polyethylenimine was employed to modify the surface functional properties of polylactic acid (PLA) films. The aim is to extend the applicability of this biopolymer, which is of great industrial interest. Surface analyses by contact angle measurements and electron microscopy demonstrated the formation of a uniform GO layer, which enhanced the surface hydrophilicity. A 10 bi-layer coated film showed oxygen permeability reduced by 70% in both dry and humid conditions, compared to the neat PLA film. The use of a water soluble reducing agent allowed for the effective room temperature reduction of the GO deposited within the film, as evidenced by IR and contact angle measurements. GO reduction resulted in a significantly decreased surface resistivity and remarkable antistatic properties, suggesting possible applications in the field of antistatic packaging.

Enhancement of Cu(II) adsorption on activated carbons by non-thermal plasma modification in O2, N2 and O2/N2 atmospheres

Abstract Activated carbon (AC) was modified by using non-thermal plasma in O2, N2 and O2/N2 atmospheres to increase its Cu(II) adsorption capacity and quantify the influences of the modifying atmospheres. SEM, BET, FT-IR and XPS were used to characterize the surface physical and chemical properties of AC. The results show that the AC modified by using plasma had significantly better Cu(II) adsorption performance than the raw AC. Among the O2, N2 and O2/N2 atmospheres, the AC with plasma modification in N2 showed best Cu(II) adsorption performance and the Cu(II) adsorption capacity was 369.5% higher than the raw AC. The AC modified in O2 atmosphere can form C—COOH groups, while the AC modified in N2 atmosphere can form C—NH2 groups. These two groups are both beneficial for Cu(II) adsorption, where the —NH2 groups are more effective for Cu(II) adsorption compared to —COOH groups. The chemisorption dominated the Cu(II) adsorption on the plasma modified AC and the adsorption performance was dependent on the surface functional groups properties of AC.

Effects of iron-based fuel borne catalyst addition on microstructure, element composition and oxidation activity of diesel exhaust particles

Metal-based fuel borne catalysts (FBC) have been extensively studied as an effective technology to reduce diesel particles and assist diesel particulate filter (DPF) regeneration. In this study, FBC fuels were prepared with Fe element mass fractions of 0, 100, 200, 300 and 400 mg/kg (marked as Diesel, Fe100, Fe200, Fe300 and Fe400). The effects of FBC additions on fuel economy and emission characteristics were carried out on a common-rail engine. Also, particle size distribution, microstructure, surface functional groups, element content and oxidation properties of exhaust particles were systematically analyzed. Results showed that the brake thermal efficiency was improved with the addition of FBC in diesel fuel, especially at low load, and the NOx and smoke emissions showed a decreasing trend. Compared with Diesel particles, the total mass concentration and the mean particle diameter of Fe300 particles decreased, the overall particle size distribution moved from coarse mode to accumulation mode, however, the total number concentration increased. Fe300 particles had larger layer spacing and microcrystalline curvature, smaller microcrystalline size and lower graphitization. In addition, the relative contents of OH and aliphatic C–H in Fe300 particles were higher than those in Diesel particles. The relative content of C atoms in Fe300 particles decreased, while the relative content of O atoms increased. Temperature-programmed-oxidation experiments indicated that semi-volatile organic components appeared in Fe300 particles, the peak temperature of weight loss rate decreased by 131 °C as compared with Diesel particles, the activation energy was also significantly lower, and therefore the particle oxidation activity was improved.

Operational temperatures of all-weather thoroughbred racetracks influence surface functional properties

The surface temperature of all-weather racetracks has previously been correlated to speed. However specific functional properties such as grip, cushioning and impact firmness have not been directly compared to environmental conditions. The objective of this study was to assess how temperature influences functional properties of racetracks, and categorise surface wax binders according to first thermal transition peak, and compare responses at different operational temperatures. Functional properties were determined for UK all-weather racetrack surfaces (n = 6) using mechanical testing equipment which assess the loads experienced by the forelimb at gallop (randomised block design). Tests were carried out using latex lined moulds, embedded within a test box with a predefined boundary at 0 °C, 20 °C and 40 °C. Wax binders underwent differential scanning calorimetry to identify thermal transition peaks. Changes in operational temperatures significantly influenced surface responses when a wax binder was part of the composition. Temperature was a factor that significantly contributed to the variation found in horizontal grip ( F 2, 237 = 65.69, P < 0.001), cushioning ( F 2, 237 = 58.24, P < 0.001), impact firmness ( F 2, 237 = 28.02, P < 0.001) and rotational grip ( F 1 2, 65 = 9.45, P < 0.001). Using a test box meant individual racetracks were generalised but this enabled conditions to be controlled. Colder temperatures demonstrated higher surface hardness and shear resistance that may increase risk of musculoskeletal injury although this was not measured here. Awareness of the effect temperature has on specific track behaviour allows maintenance protocols to be further developed to improve consistency when temperatures change, with the aim of improving safety. • Functional properties of UK racetracks alter during normal operational temperatures. • Greater variation in track cushioning and hardness was seen at lower temperatures. • Repeated drops akin to used-tracks produced higher hardness at lower temperatures. • Individual first thermal transition peak influences track response to temperature. • A first thermal transition peak <40 °C showed greater range of hardness and grip.

N-doped hierarchical porous hollow carbon nanofibers based on PAN/PVP@SAN structure for high performance supercapacitor

Carbon nanofibers (CNFs) have been continuously studied as a high performance electrode material due to their versatility in energy storage/conversion systems. The main concern of fabricating CNFs as electrode materials is to endow pristine carbon materials with adequate pore structure and active surface functional groups. Herein, we have fabricated porous hollow carbon nanofibers (PHCNF) with high nitrogen contents (13.4%) via co-axial electrospinning and subsequent phase separation process by using poly(styrene-co-acrylonitrile) (SAN) as core and polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) mixture as shell. Simple etching process prior to carbonization has a significant effect on making hierarchical pore structure. Moreover, hollow characteristics allow efficient heat treatment for making high crystalline structure and favorable nitrogen functional group. Such an optimized structural and surface functional properties result in a remarkable supercapacitor performance. The designed structure achieves an energy density of 4.12 Wh kg−1 at power density of 15 kW kg−1, and a 92.33% retention rate in 10,000 charge/discharge cycles. The results offer a new strategy for developing advanced carbon material based electrode for high performance storage devices such as supercapacitors, lithium-ion batteries, and sensors.

Effects of alumina morphology on dry reforming of methane over Ni/Al2O3 catalysts

Ni-based catalysts supported on alumina with different morphologies exhibited different properties for the dry reforming of methane due to their specific lattice planes, 3D structures, and surface functional properties.

Mineralization of phenol by ozone combined with activated carbon: Performance and mechanism under different pH levels

The degradation of phenol using ozone with activated carbon (O3/AC system) was investigated in this study. The O3/AC system was also compared with the single O3 and AC systems. The total organic carbon (TOC) removal efficiency in the O3/AC system was roughly 26% and 30% higher than the single AC and O3 systems, respectively. It was demonstrated that the phenol degradation rate and TOC removal efficiency were significantly affected by the ozone concentration, AC dosage, and solution pH. The pseudo-first-order and pseudo-second-order kinetic models were fitted to identify the mechanisms of the phenol removal process. The results of Scanning Electron Microscopy, Brunauer-Emmett-Teller, and Fourier-transform infrared spectroscopy of raw and used AC indicated that the surface morphology, microstructure, and functional group properties had been changed during the reaction process. The possible O3/AC system mineralization mechanism for phenol removal was tentatively proposed using scavenging active species such as ·OH, O2⋅−, and H2O2. The transformation byproducts generated during the application of the O3/AC system were identified by High Performance Liquid Chromatography and Gas Chromatography–Mass Spectrometry analyses. Therefore, the mineralization pathway of phenol in detail was proposed in acidic (pH 3.0) and alkaline (pH 11.0) conditions. This study provided a more systematic explanation of the mineralization mechanism for phenol in the O3/AC system.

Interactions of emerging contaminants with model colloidal microplastics, C60 fullerene, and natural organic matter - effect of surface functional group and adsorbate properties.

Surface adsorption of two commonly detected emerging contaminants, amlodipine (AMP) and carbamazepine (CBZ), onto model colloidal microplastics, natural organic matter (NOM), and fullerene nanomaterials have been investigated. It is found that AMP accumulation at these colloidal-aqueous interfaces is markedly higher than that of CBZ. Measurements of surface excess and particle zeta potential, along with pH-dependent adsorption studies, reveal a distinct influence of colloidal functional group on the adsorption properties of these pharmaceuticals. AMP shows a clear preference for a surface containing carboxylic group compared to an amine modified surface. CBZ, in contrast, exhibit a pH-dependent surface proclivity for both of these microparticles. The type of interactions and molecular differences with respect to structural rigidity and charge properties explain these observed behaviors. In this work, we also demonstrate a facile approach in fabricating uniform microspheres coated with NOM and C60 nanoclusters. Subsequent binding studies on these surfaces show considerable adsorption on the NOM surface but a minimal uptake of CBZ by C60. Adsorption induced colloidal aggregation was not observed. These findings map out the extent of contaminant removal by colloids of different surface properties available in the aquatic environment. The methodology developed for the adsorption study also opens up the possibility for further investigations into colloidal-contaminant interactions.

Promoting formic acid oxidation performance of Pd nanoparticles via Pt and Ru atom mediated surface engineering.

The alteration of surface functional properties via incorporation of foreign atoms is supposed to be a key strategy for the enhanced catalytic performance of noble-metal based nanocatalysts (NCs). In the present study, carbon-supported palladium (Pd)-based NCs including Pd, PdPt and PdRuPt have been prepared via a polyol reduction method under the same reduction conditions as for formic acid oxidation reaction (FAOR) applications. By cross-referencing the results of the microscopic, spectroscopic and electrochemical analysis we demonstrated that adding a small amount of platinum (Pt) into Pd NCs (i.e. PdPt NCs) significantly promotes the FAOR performance as compared to that of Pd NCs via weakening the COads bond strength at a lower voltage (0.875 V vs. NHE) than Pd (0.891 V vs. NHE). Of special relevance, the PdPt NC shows a mass activity (MA) of 1.0 A mg−1 and 1.9 A mg−1, respectively, in the anodic and cathodic scan. These values are ∼1.7-fold (0.6 A mg−1) and ∼4.8-fold (0.4 A mg−1) higher than those of Pd NC. Moreover, PdPt NC retains a higher MA (54 mA mg−1) than that of Pd NC (9 mA mg−1) after chronoamperometric (CA) stability tests over 2000 s. Meanwhile, further addition of ruthenium (Ru) (i.e. PdRuPt NCs) outstandingly enhances the CO tolerance during the CA test via removal of adsorbed COads and thus shows the highest MA (62 mA mg−1) after CA testing, which is higher than that of PdPt (54 mA mg−1) and Pd (9 mA mg−1) NCs. The intriguing results obtained in this study have great significance to provide further strategic opportunities for tuning the surface electronic properties of Pd-based NCs to design Pd-based NCs with improved electrochemical performance.

Application of novel Fe3O4-g-GO-g-RAFT agent nanoabsorbents for D-SPME of biogenic amines in smoked fish

Herein, a dispersive solid phase microextraction (D-SPME) approach based on magnetic nanoabsorbents was developed for the simultaneous extraction of histamine, cadaverine, putrescine, and tyramine in smoked fish. The desired magnetic nanocomposite was prepared with surface modification of Fe3O4 nanoparticles with graphene oxide via surface reversible addition fragmentation chain transfer (RAFT) copolymerization. Preparation, size, morphology, surface functional groups and magnetic properties of as-synthesized nanocomposite was characterized. The obtained results showed acceptable r2 values (≥0.9949) for all analyte as well as good recovery (>98.36), repeatability (RSD%<3.57), and reproducibility (RSD%<5.16) of the developed method. The developed method was successfully employed to estimate four biogenic amines in 40 samples from different species of smoked fishes available in northern Iran. Thirty-six out of 40 samples exceeded an acceptable level of histamine (50 mg Kg−1). Cadaverine and putrescine were founded at a higher level, while tyramine was detected at the lowest level in comparison with other BAs (<11 %).