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[Display omitted] • Adsorption and electronic properties of gases on nanoporous CN monolayer were studied. • NO, SO 2 , H 2 S, and NH 3 molecules are weakly chemisorbed on the monolayer. • Adsorption of NO, H 2 S and NH 3 efficiently tunes electronic properties of CN monolayer. • CN monolayer has high sensitivity and selectivity to NO, H 2 S and NH 3 with moderate recovery time. • CN monolayer as a good candidate for NO, H 2 S, NH 3 gas sensors at room temperature. To explore the possibility of the nanoporous CN (p-CN) monolayers as high-performance gas sensors, the adsorption, electronic properties and gas-sensing performance of various gases on the p-CN monolayers have been studied by first-principles methods. Only NO, SO 2 , H 2 S and NH 3 have weak chemisorption on the monolayer, which and the physical adsorption of NO 2 and C 2 H 4 changed efficiently the electronic properties and work function of p-CN monolayer. The p-CN monolayer towards NO, NH 3 , and H 2 S gases has comparatively high sensitivity, while has quite low sensitivity towards other gases. The characteristics on the I-V curves and work function can effectively distinguish various gases. The recovery time for NO, NH 3 , and H 2 S is about 4.1 s, 0.27 s, and 0.018 s at 300 K, respectively, which is fairly moderate for the reuse of the CN-based sensor for NO, NH 3 , and H 2 S detection. However, the over-short (or over-long) recovery time for NO 2 and C 2 H 4 (<10−6 s) (or SO 2 , c. 35 min) gravely hinders the p-CN-based gas sensors for these gases monitoring. Therefore, the p-CN monolayers as reusable gas sensors have high sensitivity and selectivity at room temperature for NO, H 2 S and NH 3 detection. [ABSTRACT FROM AUTHOR]

A novel solid fluorescent sensor with millimeter size, based on graphene quantum dots/polystyrenic anion-exchange resin (GQDs/PS-AER) was obtained for the detection of Fe 3+ . The linear response range of Fe 3+ was obtained from 1 μM to 7 μM and the detection limit was as low as 0.65 μM. In addition, the sensor could be regenerated by adding complexing agent EDTA and be separated by using simple filtration. [ABSTRACT FROM AUTHOR]

A novel and simpleapproach was used to fabricate 3D porous honeycomb-like metal-free electrocatalyst. Unique 3D hierarchically macroporous structure shortens transport distances of ions through the well-interconnected intermediate structure, which provides a continuous pathway endowing for the fast electron transport. The extremely outstanding catalytic activities of the as-developed N,P-HLC were ascribed to ordered honeycomb-like macroporous structure which provides mechanical support, facilitates the circulation of electrolyte and promote the occurrence of reactions. [Display omitted] • 1. The honeycomb-like macroporous material is obtained by a simple synthesis strategy. • 2. N, P co-doped carbon displays remarkable ORR performance in acidic and alkaline media. • 3. High activity profits from the synergistic effect of ordered macroporous carbon. The fabrication of superior oxygen reduction reaction (ORR) electrocatalysts, a challenging process, is currently focuses on expensive and rare platinum (Pt) group based metals. However, these noble metals-based electrocatalysts often suffer from disadvantages, including poor stability, exorbitant price, and low selectivity. Here, we report a simple strategy to synthesize a porous honeycomb-like carbon-based electrocatalyst codoped with nitrogen (N) and phosphorus (P) without any template. Benefiting from the synergistic impact of N, P co-doping, the as-developed honeycomb-like carbon (N,P-HLC) displays splendid ORR electrochemical activity with a large onset potential of 1.0 V (vs. RHE), and half-wave potential (E 1/2) of 0.85 V (vs. RHE). What's more, N,P-HLC displays remarkable ORR performance under the super low electrocatalyst loading capacity of 0.15 mg cm−2, which is highly comparable to benchmark Pt/C (E 1/2 = 0.83 V, loading capacity 0.38 mg cm−2). Meanwhile, N,P-HLC also exhibits exceptional ORR activity in the harsh acid conditions. This work introduces a robust, low-cost and superb electrocatalytic materials to replace the noble metal-based ORR electrocatalysts. [ABSTRACT FROM AUTHOR]

• I-doped g-C 3 N 4 were synthesized by an in-situ decomposition-thermal polymerization. • I-doped g-C 3 N 4 showed reduced band gap and extended PL lifetime. • I-doped g-C 3 N 4 exhibited enhanced photocatalytic nitrogen fixation performance. Photocatalytic nitrogen fixation has attracted great attention recently due to the mild condition with solar energy as the only energy input. In this work, the iodine-doped g-C 3 N 4 with carbon vacancies has been successfully synthesized via a one-step thermal-decomposition method. The results showed that the band gap of g-C 3 N 4 decreased and the average PL lifetime of g-C 3 N 4 increased after iodine doping. This demonstrated the expansion of light responsive range and the high separation efficiency of the photo-generated charge carriers in iodine-doped g-C 3 N 4. The g-C 3 N 4 with 10 wt% iodine doping exhibited excellent performance and well stability for the photocatalytic nitrogen fixation under simulated sunlight irradiation within 3 h (200.8 mg/L/g cat), which is 2.8 times as high as that of bulk g-C 3 N 4 , owing to the reduced band gap, existence of carbon vacancies and enhanced separation efficiency of the photo-generated charge carriers. A feasible mechanism was proposed for photoinduced charge separation and nitrogen photofixation over iodine-doped g-C 3 N 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Expandable single crystal organic precursors to form carbon composites for Li battery. • Carbon nanosheets with nickel-N-doping have high performances in cycle and rate. • Microporous-mesoporous structure formed by metal and N doping enhances Li+ adsorption. • DFT is used to study the adsorption and diffusion of Li+ in the metal-N-doping carbon. Organic-based and metal-organic-based matters are used as electrode materials or precursors for lithium ion batteries because of their high chemical stability and flexible molecular adjustability. Nevertheless, the unobvious electrochemical performance and unclear structure hinder the study of the lithium ions storage mechanism of them. In this paper, we design a well-defined single-crystal structure of organic crystal precursor (CN-Ni/Mn) and derived porous carbon nanosheets with metal-nitrogen-doping (CN-Ni/Mn-800) as electrode materials to construct independent high-performance lithium ion batteries. The study shows that a large number of interconnected micropore mesoporous structures obtained by the transformation of macropores in the materials improve the lithium storage capacity. Density functional theory (DFT) calculations show that the lithium ions adsorption energy and diffusion ability of CN-Ni/Mn-800 are higher than those of N-doped carbon-based materials (CN-800). CN-Ni-800 has the best performance among the anode materials of the half battery. It can deliver stable long-term cycling performance over 1000 charge-discharge cycles at 500 mA g−1. This is a new strategy that designed precursors with a single-crystal structure to derive carbon-based materials for developing high-performance batteries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A flexible resistive memory device based on MoS 2 –rGO hybrid was reported firstly. • The device shows a low operating voltage (about 0.4 V), and multilevel states by controlling the compliance current. • The effect of resistive switching ascribes from the electron trapping and de-trapping in the MoS 2 –rGO heterojunction. Abstract With the growing demand for wearable electronic devices in recent years, flexible memory devices have attracted great interest among researchers. Here we report a flexible resistive memory device based on a hybrid of MoS 2 and reduced graphene oxide (rGO). The device shows not only a low operating voltage (about 0.4 V), but also multilevel states by controlling the compliance current. In addition, it exhibits long retention time, high repeatability, and bending endurance. Further analysis indicates that the resistive-switching phenomenon can be attributed to the effect of electron trapping and de-trapping in the MoS 2 –rGO heterojunction. Our findings suggest that the MoS 2 –rGO hybrid has the potential to be applied in flexible, low-power, and high-density nonvolatile memory. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The MoS 2 /RGO and MoS 2 /Fe 3 O 4 hybrids are prepared by a facile synthesis route. • The MoS 2 /RGO and MoS 2 /Fe 3 O 4 hybrids with hetero-structures exhibit excellent microwave absorption properties. • Tailoring weight percentage and thickness tunes microwave absorption for high efficiency and broad bandwidth. • The mechanisms of high-performance microwave absorption of MoS 2 /RGO and MoS 2 /Fe 3 O 4 hybrids are elucidated. Abstract The two-dimensional (2D) transition metal dichalcogenide, molybdenum disulfide (MoS 2), has been demonstrated to be a new class of microwave absorption (MA) material due to its high specific surface area and peculiar electronic properties. However, its limited MA capacity and bandwidth require further improvement. MoS 2 /RGO composites with improved MA performance have been reported, but the complicated and inefficient preparation process also limits the application of MoS 2 /RGO composites. In this work, we prepare MoS 2 /RGO hetero-structure hybrid with excellent MA performance and broadened bandwidth by a facile one-step hydrothermal method. It is found that the highest reflection loss value of the sample-wax containing 40% MoS 2 /RGO is −49.41 dB at a thickness of 2.52 mm, and the bandwidth of RL values less than −10 dB can reach up to 13.36 GHz (from 4.64 to 18 GHz). Meanwhile, we investigate another strategy to prepare MoS 2 /Fe 3 O 4 hybrid with hetero-structures and their MA performance is studied for the first time. It is found that the highest reflection loss value of sample-wax containing 40% MoS 2 /Fe 3 O 4 is −42.57 dB at a thickness of 3.25 mm, and the bandwidth of RL values less than −10 dB can reach up to 12.73 GHz (from 5.27 to 18 GHz). Results obtained in this study open a new window for designing excellent MA materials for practical applications. [ABSTRACT FROM AUTHOR]

Ag-decorated TiO 2 inverse opal films (ATIO) with high surface-enhanced Raman scattering (SERS) enhancement were prepared using an electroless deposition process. The Ag nanoparticles (NPs) are well-dispersed and deposited on the edge of macroporous walls. The structure and optical properties of the sample ATIO have been characterized. The Ag-loading cycles and pore sizes of TiO 2 inverse opal are the key factors determining the magnitude of SERS signal enhancement. The optimized ATIO samples exhibit high SERS signal enhancement ability and reproducibility. The enhancement factor about 10 4 and the detection limit of 10 −10 M for R6G were achieved. The further application in detecting malachite green is demonstrated. A limit of detection approximately 10 −9 M was achieved. The results show that the ATIO nanostructure is promising for using as sensor substrates in SERS applications. [ABSTRACT FROM AUTHOR]

Abstract: The CrN(C) coatings with different carbon contents were deposited using unbalanced magnetron sputtering via adjusting the carbon target current, and their microstructure and mechanical properties were characterized using Raman spectrum, X-ray photoelectron spectroscopy and nano-indenter, respectively. The water-lubricated tribological properties of the CrN(C) coatings against Si3N4 balls were investigated using the ball-on-disk tribometer. The results showed that the C content in the CrN(C) coatings increased gradually, and the peak intensity correlated to Cr7C3 crystal phase became stronger when the carbon target current increased. When the carbon target current was 1A, the hardness of the CrN(C) coatings increased to 22.5GPa due to formation of Cr7C3 phase and amorphous CN x , and a little amorphous carbon had positive effect on tribological properties of the CrN(C) coatings in water lubrication. On the other hand, CrN(C) coatings deposited at 2–4A exhibited a lower hardness and deteriorated tribological properties, due to the presence of a major amount of Cr2O3 particles in the films. [Copyright &y& Elsevier]

Superior nonprecious Co/Co-N x -PCNSs bifunctional oxygen electrocatalyst was successfully fabricated through cost-efficient active carbonaceous spheres templates strategy. These unique structural characteristics endowed the electrocatalyst with abundant accessible electrocatalytic sites, and gave rise to superb electrocatalytic activity, in terms of positive E onset , large E 1/2 , superb durability for ORR, and a low potential at j = 10 mA cm−2 for OER. Impressively, the as-fabricated rechargeable Zn-air battery afforded a high peak power density, and robust charge/discharge stability. • Co/Co-N x -PCNSs electrocatalyst was obtained by active carbonaceous spheres strategy. • The electrocatalyst possessed plentiful active sites, and high nitrogen dopant. • The bifunctional oxygen electrocatalyst gave rise to superb electrocatalytic activity. • The Zn-air battery afforded high peak power density and robust charge/discharge stability. Developing low-cost and high-performance nonprecious metal electrocatalysts for oxygen reduction (ORR) and oxygen evolution reaction (OER) are the crucial factors for advancing the renewable energy conversion and storage technologies, such as, Zn-air batteries. Here, we report on a novel templates approach to fabricate Co nanoislands activated Co,N-doped porous carbon nanospheres (Co/Co-N x -PCNSs) bifunctional oxygen electrocatalyst with high density Co-N x , and graphitic carbon shell active sites. The obtained Co/Co-N x -PCNSs exhibit the highest ORR activity with large E onset (onset-potential) of 0.98 V vs RHE, more positive E 1/2 (half-wave potential) of 0.85 V vs RHE and large limited current density (j) of 6.6 mA cm−2 in 0.1 M KOH solution. For OER, they exhibit remarkably stable OER performance with potential as low as 1.58 V at 10.0 mA cm−2 and the small Tafel slop of 53 mV dec−1. The encouraging electrocatalytic performance can be ascribed to the high density of accessible active sites, low work function derived from Co nanoarchitecture activated graphitic carbon shell. The constructed Zn-air batteries display a large power density of 140 mW cm−2 and small potential gap 0.79 V. Strategy developed herein provides a promising technique for the rationally fabrication of efficient nonprecious metal electrocatalysts. [ABSTRACT FROM AUTHOR]

• The diamond nucleation density was enhanced to 5 × 1011/cm2. • Pinhole-free ultrathin diamond films with a thickness of 45 nm were synthesized. • In UV–Vis range, the transparency of coated quartz was 90% in air and 98% underwater. • The coated quartzs exhibit excellent anti-fogging and underwater self-cleaning performances. • The nanofilms possess superior mechanical stability with ultra-low friction coefficient. Fouling and abrasive wear severely affect the transparency of optical sensors and windows employed in marine, biomedical and aerospace applications. Herein, we report a strategy to create a robust and superhydrophilic surface based on ultrathin transparent diamond nanofilms synthesized by an enhanced self-assembly seeding and chemical vapor deposition approach. A quartz glass coated with an ultrathin (~50 nm) and smooth diamond nanofilm exhibits a high optical transparency of 90% in air and 98% underwater in UV–Vis range. Especially, an IR transmittance of 85% is recorded, which is even 10% higher than that of uncoated quartz. The transparent diamond nanofilms are superhydrophilic and underwater superoleophobic after oxygen plasma treatment, leading to the anti-fogging capability in air and underwater self-cleaning of oil. Importantly, the quartz coated with the diamond nanofilms shows excellent mechanical robustness with unchanged morphology and transparency under severe sandblasting condition. Moreover, this ultrathin diamond nanofilm can make the deposited substrates self-lubricating, which significantly decreased the friction coefficient of the quartz from 0.18 to 0.05. High transparence from ultraviolet to infrared and intriguing performances of the ultrathin diamond nanofilms make them promising for several important applications, such as aircraft fairing and window, optical lens, and marine exploration, etc. [ABSTRACT FROM AUTHOR]