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The water adsorption on Fe (100) surface with and without surface tensile strain is studied by spin-polarized self-consistent density functional theory calculations to elaborate the influence of tensile strain on surface chemistry. We find that the surface tension not only enhances the interaction between water and surface but also lowers the energy barrier for water dissociation on the surface. The dissociated reactive OH fragment may further attack the iron surface and the dissociated reactive H fragment could transfer into iron lattice and cause H embrittlement. This study clearly shows that the stressed induced surface chemistry could be an important aspect of stress-corrosion cracking (SCC) in iron based materials.

Magnetic nano capture agent (MNCA)-based magnetic separation can remove heavy metals from blood efficiently and safely. It has been considered as the next-generation therapy for heavy metal intoxication. In this work, we report the first use of MNCA to remove arsenic (As) with high efficiency from blood. MNCA with a flexible, non-covalent and biocompatible surface layer has been synthesized by packaging cetyltrimethylammonium bromide (CTAB) and bovine serum albumin (BSA) together with oleic acid coated magnetic iron oxide nanoparticles (MNP@OA) via Van der Waals force. This surface layer enhances arsenic anion diffusion from the surface to the binding sites, leading to increased arsenic removal performance of MNCA. The adsorption capacities of BSA and CTAB enfolded MNP@OA (MNP@CTAB-BSA) for As (III) and As (V) are 131.00 mg g−1 and 119.58 mg g−1, respectively. 89.02% of As (III) and 81.78% of As (V) are removed from blood using MNP@CTAB-BSA, and the residual concentrations of As (III) and As (V) in blood decrease from 400.00 μg L−1 to 43.93 μg L−1 and 72.88 μg L−1, respectively. The as-synthesized MNP@CTAB-BSA shows excellent biocompatibility. Under operation condition, only 0.80% of hemolysis and 1.64% of plasma protein adsorption are induced by MNP@CTAB-BSA, and the cell viability of peripheral blood mononuclear cells (PBMCs) is more than 95.53%. This study paves a fast, safe and effective way for arsenic intoxication therapy.

Recently, surface with desirable gradients has been proved to be a powerful tool for diverse applications from biological systems and chemical analysis to material science. In this work, we demonstrate a versatile and universal approach to realize controllable physicochemical properties in orthogonal gradients on polydimethylsiloxane (PDMS) surface. Based on a novel microfluidics network, we can easily establish the concentration gradients within the microfluidic channel for surface polymerization or chemical deposition to realize the stable characteristic gradient on the PDMS substrate. The method was introduced to prepare surface with two-dimensional physical (roughness) gradients, or combinational physicochemical gradients to study the synergistic effect on interested phenomenon. As a proof of concept, the experimental results show that the as-prepared substrate can effectively influence in various fields, such as protein adsorption and nano-particle immobilization, which can potentially be used for future systematical study in biological systems or practical applications in bio/chemical analysis/sensing.

We report a facile route to synthesize porous Sn nanocrystals@acetylene black microspheres (Sn@AB MSs) via a galvanic replacement reaction of Zn microspheres in a SnCl2 solution consisting of acetylene black (AB). The half cells of lithium-ion batteries with the Sn@AB MSs as the working electrode have a charge capacity of 480.8 mA h g−1 at 100 mA g−1 after 100 cycles, and the charge capacity of the half cells after the 100th cycle is slightly larger than that after the 80th cycle. The SEM images reveal that the electrode layer from the Sn@AB MSs experiences surface cracking during electrochemical cycling, while prolonged cycling leads to the closure of cracks. Electrochemical cycling induces self-organization of Sn and AB to form rose-like porous Sn@AB/Li2SnO3 microflowers from porous Sn@AB MSs. The closure of cracks and formation of porous Sn@AB/Li2SnO3 microflowers likely cause the increase of the charge capacity. The experimental results demonstrate that the porous Sn@AB MSs with acetylene black around Sn can alleviate the large volumetric strain due to lithiation/delithiation, reduce the migration distance of lithium to active sites, and promote exceptional Li storage, leading to better cycling stability.

We propose a non-metallic g-C3N4 nanosheet with efficient photo-oxidation and reduction ability that is modified by two non-metallic materials graphene and polypyrrole. The composite was tested by water treatment, including hexavalent chromium and phenol. It offers a visible response, easy recovery, and high stability, with a higher photo-degradation rate than bulk g-C3N4. The photoelectric performance test showed that the composite has a reduced Eg (2.58 eV) that is 0.12 eV lower than g-C3N4 (2.70 eV). The rGH can transfer electrons, and ppy can transfer holes, which helps improve the separation rate of photogenerated charge of the g-C3N4. When ppy and rGH operate concurrently, the separation of the photogenerated charge is greatly improved. In addition, the results of Vb-XPS show that the value of the valence band top of the hybrid hydrogel is more negative than bulk g-C3N4. Therefore, the π-π conjugation of ppy and rGH can effectively improve the utilization rate of visible light, the photogenerated transfer rate, the photocatalysis-oxidation ability, and the change in valence band position of g-C3N4.

The composite photocatalyst Ag3PO4@P3HT with core-shell structure was synthesized through a simple method, and SEM, TEM and FTIR were used to detect the presence of P3HT in the composite catalyst and to confirm its structure. The sample’s photodegradation ability was studied by degradation the organic pollutants phenol and BPA under visible light irradiation. Through experimental tests the photocatalytic activity was the highest at 0.07 wt% P3HT, and the degradation of phenol increased by about 23% compared to Ag3PO4. At the same time, and with the same concentration of BPA, the degradation increased by about 25% in 6 min. Photoelectricity, UV–vis spectroscopy, and PL testing were used to study the electrochemical and optical properties of the catalysts. It is concluded that the increase in photocatalytic activity is due to the enhancement of visible light absorption, the more efficient separation of photogenerated e−/h+, and the faster transfer of photogenerated carriers. Finally, the mechanism of enhanced photocatalytic activity was discussed in terms of band position.

PtO nanodots (∼2.5 nm) with high crystallinity are homogeneously deposited on the surface of g-C3N4 by a two-step refluxing-calcination method. XPS analysis indicates that a strong interaction is formed between PtO and g-C3N4, which is beneficial for the transportation of charge carriers from g-C3N4 to the co-catalyst and therefore results in a prolonged carrier life time in the composite. A series of electrochemical tests, including EIS, LSV and OCVD prove that PtO can significantly enhance the conductivity and light response of g-C3N4 compared with Pt. PtO and Serving as hydrogen evolution sites, the highly dispersed PtO nanodots can shorten the diffusion path lengths for photogenerated electrons in the host photocatalyst as well as suppress the undesired hydrogen oxidation reaction. Remarkably, PtO coupled g-C3N4 (0.19 wt% Pt) exhibits excellent hydrogen production activity, giving a turnover frequency of 552.7 h−1, which is 51 times that of Pt nanoparticles confined g-C3N4. The PtO nanodots also display high photostability and would not agglomerate into clusters or be reduced by the photogenerated electrons even after 40 h of irradiation. The present work also provides a new method for synthesis of high performance co-catalysts with low Pt content used in other photocatalytic reactions and energy applications.

The precise control of the selectivity of intermediates in nitrobenzene reduction is a time-honored challenge. Herein, we report a regulatory method for improving the selectivity of azoxybenzene using four rationally tailored CeO2 catalysts, whose exposed planes, acid–base chemistries, and defect properties in terms of Ce3+ cations and O-vacancies are optimized. Among the four catalysts, Spindle-structured CeO2, which has the largest concentration of Ce3+ cations and O-vacancy defects exhibits the highest nitrobenzene conversion rate. However, it exhibits a lower azoxybenzene selectivity (70.5%) than Rod-CeO2 (90.4%). Based on the semi-quantitative characterization results and the initial rates of the rate-determining step, the defect densities of the CeO2 catalysts are demonstrated to correspond to their catalytic selectivity. Density functional theory (DFT) calculations and in situ capping tests further reveal that the parent Ce3+ cations of O-vacancy defects serve as adsorption-activation sites for nitro groups of nitrobenzene. Moreover, the O-vacancy defects serve as the main active sites and conduce the over-reduction of azoxybenzene, which should be inhibited to improve the azoxybenzene selectivity. Therefore, regulating the O-vacancy defects at the moderate concentration is responsible for the satisfactory azoxybenzene yield of 90.4% exhibited by Rod-CeO2 nanocrystals.

To investigate the effect of imidazolium ionic liquid with poly(ethylene glycol) segment (IL) on the polar phase crystallization behavior of poly(vinylidene fluoride) (PVDF), a series of PVDF/IL composites were prepared using solution-cast method. The crystallization peak temperature of PVDF composites and the growth speed of samples decrease with increasing of IL. The >CF2 groups in amorphous region are retained and >CF2 groups in crystalline region are liberated by the PEG long soft segments of IL. The intensity of peaks represented as α phase reduces, moreover polar phase content increases with increasing of IL. The interaction between the >CF2 and the imidazolium cation can induce the polar phase, and the interaction between the >CF2 and PEG soft segment can strengthen polar crystalline induction. PVDF/12IL composite can form big γ spherulite circled by β phase.

We describe a controllable sliding method for fabricating millions of isolated femto- to nanoliter-sized droplets with defined volume, geometry and position and a speed of up to 375 kHz. In this work, without using a superhydrophobic or superoleophobic surface, arrays of droplets are instantly formed on the patterned substrate by sliding a strip of liquid, including water, low-surface-tension organic solvents and solution, along the substrate. To precisely control the volume of the droplets, we systemically investigate the effects of the size of the wettable pattern, the viscosity of the liquid and sliding speed, which were found to vary independently to tune the height and volume of the droplets. Through this method, we successfully fabricated an oriented single metal–organic framework crystal array with control over their XY positioning on the surface, as characterized by microscopy and X-ray diffraction (XRD) techniques.