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Potassium ion batteries (KIBs) and potassium-based dual ion batteries (KDIBs) are newly-emerging energy storage devices that have attracted considerable attention owing to the low-cost of potassium resources and their comparable performance to lithium-ion batteries (LIBs). Graphite materials, as the successful commercialized anode materials of LIBs, can also be used as anodic and cathodic host materials for the intercalation of the large potassium cations and other anions, respectively. However, there are still some challenges hindering the practical application of graphite materials in the anode for KIBs and the cathode for KDIBs. The huge volume changes after intercalation (61% for K and 130% for anions) result in graphite interlayer slipping and structural collapse, causing capacity fade and a short cycle life. Moreover, the intercalation of large K+ and anions have poor kinetics due to the small graphite interlayer spacing, restricting the rate capability. To solve these issues of the use of graphite materials, this review attempts to provide a better understanding of the intercalation mechanisms for K+ and anions, and to correlate the electrochemical performance of KIBs and KDIBs to the microstructure of graphite, and the physicochemical properties of electrolytes and binders. Finally, research prospects are provided to guide the future development of graphite materials for potassium-based energy storage.

Dense carbon materials with fast sodium storage performance are strongly desired for developing high-energy and high-power devices, but remain challenging because of the sluggish Na+ transport kinetics. Herein, we report that the defect density and sp2 cluster size of dense graphene blocks (DGB) can be elaborately modulated by ball-milling to achieve both high gravimetric and volumetric capacities and outstanding rate performance for Na+ storage. The loose graphene flakes are cut into small platelets with enriched defects and simultaneously densified by mechanical forces, leading to abundant active sites for Na+ storage, controlled sp2 size as conductive networks, and large interlayer spacing for fast Na+ transport. The DGB performs a novel capacitive Na+ storage with high capacities of 507 mAh g−1 and 397 mAh cm−3 at 50 ​mA ​g−1, and an ultrahigh rate of 181 mAh g−1 at 10 ​A ​g−1. It also shows a remarkable cycle stability due to the strongly-coupled layer structure. The comprehensive performance is superior to most of the reported carbons. The Na-ion capacitor delivers an ultrahigh energy density of 45 ​Wh kg−1 even at 14,205 ​W ​kg−1. Our work broadens the avenue for preparing advanced carbon materials for compact Na+ storage.

Herein, we prepared novel three-dimensional (3D) gear-shaped Co3O4@C (Co3O4 modified by amorphous carbon) and sheet-like SnO2/CC (SnO2 grow on the carbon cloth) as anode and cathode to achieve efficient removal of 4-nitrophenol (4-NP) in the presence of peroxymonosulfate (PMS) and simultaneous electrocatalytic reduction of CO2, respectively. In this process, 4-NP was mineralized into CO2 by the Co3O4@C, and the generated CO2 was reduced into HCOOH by the sheet-like SnO2/CC cathode. Compared with the pure Co0.5 (Co3O4 was prepared using 0.5 g urea) with PMS (30 mg, 0.5 g/L), the degradation efficiency of 4-NP (60 mL, 10 mg/L) increased from 74.5%–85.1% in 60 min using the Co0.5 modified by amorphous carbon (Co0.5@C). Furthermore, when the voltage of 1.0 V was added in the anodic system of Co0.5@C with PMS (30 mg, 0.5 g/L), the degradation efficiency of 4-NP increased from 85.1%–99.1% when Pt was used as cathode. In the experiments of 4-NP degradation coupled with simultaneous electrocatalytic CO2 reduction, the degradation efficiency of 4-NP was 99.0% in the anodic system of Co0.5@C with addition of PMS (30 mg, 0.5 g/L), while the Faraday efficiency (FE) of HCOOH was 24.1 % at voltage of −1.3 V using the SnO2/CC as cathode. The results showed that the anode of Co3O4 modified by amorphous carbon can markedly improve the degradation efficiency of 4-NP, while the cathode of SnO2/CC can greatly improve the FE and selectivity of CO2 reduction to HCOOH and the stability of cathode. Finally, the promotion mechanism was proposed to explain the degradation of organic pollutants and reduction of CO2 into HCOOH in the process of electrocatalysis coupled with advanced oxidation processes (AOPs) and simultaneous CO2 reduction.

Rational modification by functional groups was regarded as one of efficient methods to improve the photocatalytic performance of graphitic carbon nitride (g-C3N4). Herein, g-C3N4 with yellow (Y-GCN) and brown (C-GCN) were prepared by using the fresh urea and the urea kept for five years, respectively, for the first time. Experimental results show that the H2 production rate of the C-GCN is 39.06 μmol/h, which is about 5 times of the Y-GCN. Meantime, in terms of apparent quantum efficiency (AQE) at 420 nm, C-GCN has a value of 6.3% and nearly 7.3 times higher than that of Y-GCN (0.86%). The results of XRD, IR, DRS, and NMR show, different from Y-GCN, a new kind of functional group of N CH was firstly in-situ introduced into the C-GCN, resulting in good visible light absorption, and then markedly improving the photocatalytic performance. DFT calculation also confirms the effect of the N CH group band structure of g-C3N4. Furthermore, XPS results demonstrate that the existence of N CH groups in C-GCN results in tight interaction between C-GCN and Pt nanoparticles, and then improves the charge separation and photocatalytic performance. The present work demonstrates a good example of “defect engineering” to modify the intrinsic molecular structure of g-C3N4 and provides a new avenue to enhance the photocatalytic activity of g-C3N4 via facile and environmental-friendly method.

With the ever-increasing demands for miniaturization of high-power supercapacitors, carbon materials maintaining good rate capability at high mass loadings are urgently needed. Herein, we prepare mesopore-dominated hollow carbon nanoparticles with good capacitive performance from commercial carbon black through an extremely simple air oxidation method. Taking advantage of the crystallinity inhomogeneity of carbon black nanoparticles, the hollow carbon nanoparticles are prepared by selective removal of the amorphous cores while maintaining of the ordered skins. The hollow carbon nanoparticles show large inner cavities, perforated mesoporous structure, and increased surface area from 87.4 to 753.2 m2 g−1, providing abundant electrolyte reservoirs, ion migration channels, and active sites especially for thick electrodes. The sample shows a dramatically enhanced capacitance from 5 F g−1 of the carbon black to 175 F g−1. Importantly, the assembled symmetric device exhibits high areal capacitance of 2.31 F cm−2 at 1 A g−1 and remarkable rate performance of 1.59 F cm−2 at 10 A g−1 even with an ultrahigh mass loading of 15 mg cm−2. Our work helps the deep understanding of the structural transformation of carbon black, and provides a scalable preparation route for hollow carbon nanoparticles with great potential for supercapacitors application.

Developing highly efficient and stable photocatalysts for hydrogen (H2) evolution is a great challenge. Herein, a novel strategy using ultrathin black phosphorus (BP) as a bridge joint was proposed for controllable construction of a sandwich-type Pt-containing covalent triazine-based framework photocatalyst, CTF-BP-Pt. The as-prepared CTF-BP-Pt not only significantly enhances the stability of Pt nanoparticles but also dramatically improves the charge separation efficiency of the photocatalyst. For the first time, this work reveals that the unique Pt(δ+)–P(δ−)–N(δ+) surface bonding states in CTF-BP-Pt lead to a greatly improved H2 evolution rate (614.6 μmol g−1 h−1) compared with that of CTF directly doped with Pt (CTF/Pt, 167.5 μmol g−1 h−1). In addition, the Pt(δ+)–P(δ−)–N(δ+) configurations enabled the reduction of loading amount of Pt from the normal 2 wt% to 0.05 wt% but did not remarkably decrease the H2 evolution rate. It is noteworthy that the H2 evolution rate and its turnover frequency (TOF) obtained over the CTF-BP-Pt with 0.05 wt% Pt are much higher than those of other Pt loaded carbonaceous materials. Finally, the improvement of photocatalytic performance of CTF-BP-Pt was well explained based on many characterization experiments. The present work marks a critical step toward developing high-performance and low-cost photocatalytic H2 evolution materials.

A facile and effective impregnation combined with photo-deposition approach was adopted to deposit cadmium sulfide (CdS) nanoparticles on CTF-1, a covalent triazine-based frameworks (CTFs). In this system, CTF-1 not only acted as supporter but also served as photocatalyst and electron donor. The performance of the obtained CdS deposited CTF-1 (CdS-CTF-1) nanocomposite was evaluated by H2 evolution reaction under visible light irradiation. As a result, CdS-CTF-1 exhibited high H2 production from water, far surpassing the CdS/CTF-1 nanocomposite, in which CdS was deposited via solvothermal method. The high activity of CdS-CTF-1 was attributed to the confined CdS nanoparticles with small size, leading to expose more active sites. In addition, time-resolved spectroscopy indicated that the superior performance of CdS-CTF-1 also can be ascribed to the fast electron transfer rate and injection efficiency (KET = 0.18 × 109 s−1, ηinj = 39.38%) between CdS and CTF-1 layers, which are 3.83 times faster and 4.84 times higher than that of CdS/CTF-1 nanocomposite. This work represents the first example on using covalent organic frameworks (COFs) as a support and electron-donor for fabricating novel CdS-COF nanocomposite system and its potential application in solar energy transformations.

Silicon (Si) is the most promising next-generation anode of lithium-ion batteries (LIBs), which has attracted considerable interest due to its high theoretical capacity, low lithium storage potential and rich resource reserves. However, the development of Si anode is still hindered by many obstacles, such as large volume change during lithium insertion/extraction and low electrical conductivity. Recently, abundant Si/C composites have been designed to overcome the problems of Si anode. However, most preparation methods are complicated and difficult for industrialized applications and the Si nanoparticles in composites are usually coated with disorder carbon. In this work, we designed an onion-like Si/C composite through a simple one-step injection pyrolysis using pyridine as the carbon source. In this way, Si nanoparticles were successfully encapsulated into onion-like carbon shells. When used as the anode material for LIBs, this composite exhibits outstanding Li-storage performance with the capacity as high as 1391 mAh g−1 after 400 cycles at a current density of 0.2 A g−1 and rate capacity retention of 63.9% at 2 A g−1 to 200 mA g−1. The excellent electrochemical performance mainly benefits from higher structure stability and better buffer effect of the unique onion-like structure for expanded Si nanoparticles. In addition, in this process we can easily control the lithium storage capacity and particle size in gradient through changing the raw material ratio of pyridine to Si nanoparticles. Hence, we have developed a facile method to prepare onion-like Si/C anodes, which can effectively improve the capacity and cycle life of commercial LIBs.

Gas drainage is an important method to prevent and control gas disasters. Sealing materials have an important impact on the gas drainage effect. To improve the extraction rate, the configuration and related characteristics of sealing materials were studied in this study. It was found that the fluidity increased gradually with the increase of the dosage of the suspension concentrate (SC). The water-cement ratio was directly proportional to the setting time of the slurry. Also, the mixing amount of the special cement was inversely proportional to the setting time of the slurry. The influence of the amount of foaming agent, special cement, and suspending agent on the expansion rate of the slurry was positive, and the influence gradually weakened. When the water-cement ratio of cement-based materials was 0.6, the special cement content percentage was 6, the suspension agent content percentage was 3, the plasticizer content percentage was 0.7, the early strength agent content percentage was 1.2, and the foaming agent content percentage was 0.2, the sealing effect was the best. The research results suggest that the porosity and pore length of the cement-based material are smaller than those of polyurethane, and its sealing property was better. This could further increase the sealing effect of the gas borehole, thereby facilitating gas extraction.

This study was purposely designed to evaluate the potential of faba bean (Vicia faba) residues as green manure in a maize-faba bean rotation system. Seed germination test and pot experiments were conducted to measure the effects of aqueous extract on maize seed germination and the effects of residues on crop growth and soil microbial activities. Litterbag experiment was conducted to analyze the decomposition patterns of faba bean residues during maize growing season in a regosol soil. The faba bean was separated into roots, stems, leaves, aboveground parts, and whole plants. Seed germination and the lengths of radicle and plumule were lower than those of the control, particularly with 1% aqueous extract concentrations. Aboveground biomass of maize at heading stages was negatively reduced by whole plant, aboveground part, and stem, whereas positively increased by leaf. Faba bean residues varied in their influences on the contents of soil microbial nitrogen and carbon as well as enzyme activities, mainly attributing to their differences in nutrient quality and allelophathy. Faba bean residues showed a quick decomposition rate during the first 5 weeks and slightly decomposed thereafter. The amount of nitrogen (N) released into soil ranged from 3.74 kg N ha−1 in root to 34.67 kg N ha−1 from leaf in the first 5 weeks. Compared with other plant parts, there were more remaining residues in root and stem residues. These results suggest that different management strategies should be taken to balance their negative and positive effects when using faba bean residues as green manure.

The search of novel visible-light-responsive porous materials is important because they hold great promise for applications in various fields. Herein, we report a novel strategy based on postsynthetic covalent modification for fabrication of hierarchical porous metal-organic frameworks/covalent organic frameworks (MOF/COF) hybrid materials. For the first time, benzoic acid-modified covalent triazine-based frameworks (B-CTF-1) are covalently bonded with MOFs (NH2-MIL-125(Ti) or NH2-UiO-66(Zr)) by using this strategy. Photocatalytic results show that the hydrogen production rate over 15 wt% NH2-MIL-125(Ti)/B-CTF-1 (15TBC) is 360 μmol·h−1·g−1 under visible light irradiation, which is more than twice as much as that of the B-CTF-1. Meanwhile, the hybrid materials show higher stability as compared to the simple heterostructures of MOFs and COFs connected via Van der Waals force. Photoelectrochemical analyses and controlled experiments indicate that the superior photocatalytic performance of the MOF/COF hybrids can be attributed to the formation of amide bonds between B-CTF-1 and MOFs, which facilitate the charge separation efficiency and improve the stability of the photocatalyst. Finally, a possible mechanism to well explain the improved photocatalytic performance of the photocatalytic system was proposed. The present work provides a new idea to construct highly efficient and stable MOF/COF hybrid systems and broaden the applications of COF-based materials.

A general strategy via chemically covalent combination was reported to fabricate heterostructured catalysts of carbon nitride/covalent organic frameworks (CNFs), which show superior photocatalytic activity and higher stability as compared to the conventional heterostructures of CN and COFs connected via van der Waals forces.

To understand the effects of thermal shock on microcrack propagation and permeability in coal, thermal shock tests were conducted on coal specimens by using a constant temperature drying oven (105 °C) and a SLX program controlled cryogenic tank. The growth and propagation of microcracks were measured with computer tomography (CT) scanning and scanning electron microscope (SEM) tests. Results showed that thermal shocks improved the permeability of coal significantly. Notably, the permeability of coal after thermal shocks increased from 211.31% to 368.99% and was positively correlated with temperature difference. CT scanning images revealed that thermal shocks increased the crack number, crack volume and crack width as well as smoothened and widened the gas flow paths, thereby enhancing coal permeability. Moreover, SEM images showed that heating-cooling shocks created more new microcracks, forming more complex crack propagation paths and better connectivity among microcracks in coal compared to cooling shocks. We proposed a crack propagation criterion for coal to explain the mechanism of crack failure and propagation during thermal shocks. Our experiment results and theoretical analysis indicate that the heating-cooling shock is more effective in damaging and breaking coal than the cooling shock. Thus, it can be used as an alternative approach to enhance coal permeability in the production of coalbed methane (CBM).

Owing to the abundance of potassium resources and compared performance to Lithium-ion batteries (LIBs), Potassium ion batteries (KIBs) are becoming an important supplement to the energy market dominated by LIBs now. Graphitic carbon is a mainstream anode material for LIBs, and also has great potential as anode of KIBs. But due to the limited layer spacing of graphitic carbon, the intercalation of large K+ results in poor rate and low temperature performance and limited life of battery. Here, microspheres knitted by robust carbon nanotubes (CNTs) are constructed through one step injected pyrosis using thiophene as both carbon and co-catalyst source, ferrocene as both catalyst precursor and part carbon source and followed by graphitization, finally giving graphitic carbon with both toughness and rapid ionic conductivity. When used as the anode of KIBs, it presents a stable and slight increased capacity of 155.5 mAh g−1 after 1000 cycles at 1C due to stability of unique structure. It is proven that local amorphization of carbon in the pore increases more K+ storage active sites, resulting an increased capacity with cycle. Moreover, the anode can achieve high power density with depotassiated capacity of 164.3 mAh g−1 as current density high as 70C (less than 1 min) and outstanding low temperature performance with 167.8 mAh g−1 at −40℃, proving its super dynamic and potential in low temperature scenarios. All in all, the unique structurally engineered graphitic carbon provides an insightful idea to promote the further application of graphite anode for KIBs.

To examine the characteristics of the anisotropic seepage of the coal containing gas, a study of the anisotropic seepage rule of the coal containing gas was carried out based on the tri-axial seepage experimental system with raw coal samples. The calculation method determined the principal value and the azimuth of the anisotropic permeability of the coal containing gas. Also, the permeability anisotropic ratio of the coal containing gas was defined. The permeability anisotropic dynamic variation rule and the phenomenon of the change of the dominant flow direction of the coal containing gas were thoroughly analyzed. The results showed that the flow of the methane in the coal had very obvious characteristics of anisotropy. The calculation method of anisotropy permeability of the coal containing gas proposed in this study was found to be simple and effective. The coal containing gas displayed strong stress-sensitivity. The variation rule between the permeability of the methane in the coal and the effective stress was determined to be in accordance with the negative exponential function. The change of the permeability anisotropy of the gases in the coal with effective stress showed an obvious dynamic change law of development, and changes were observed in the dominant flow direction of the gas in the coal.

CdS nanoparticle-decorated covalent triazine-based frameworks (CdS NPs/CTF-1) were controllably synthesized via a facile one-pot solvothermal method. Due to the Lewis basic nature of well-defined nitrogen sites in triazine units of CTF-1, highly dispersed and size-controlled CdS NPs were obtained and stabilized on the surface of CTF-1 layers. The as-prepared CdS NPs/CTF-1 assembly showed higher photocatalytic activity in a hydrogen evolution reaction under visible light irradiation as compared with pure CdS and CTF-1 and their physical mixture. The superior photocatalytic performance observed over CdS NPs/CTF-1 was ascribed to the highly dispersed CdS NPs with strong interaction to CTF-1 layers. The strong NP-on-layer interactions between CdS and CTF-1 in the CdS NPs/CTF-1 assembly can not only facilitate the photogenerated charge separation rates, but can also shape CdS with a nanosized structure and high stability. This study develops a new strategy to improve the photocatalytic performance and conquer the photocorrosion of CdS, and also provides some guidance for us in the development of other CTF-incorporated nanocomposite photocatalysts.

Sodium ion hybrid capacitors (SIHC) have attracted extensive interest owing to their both high energy and power densities as well as long cycle life. Herein, a novel dual-carbon SIHC is assembled with hierarchical porous hollow multicavity carbon spheres (HMCSs) as an intercalated anode and activated HMCSs (AHMCSs) as a capacitive cathode. The HMCSs are prepared from aniline and pyrrole through a one-step carbonization with F-127 as soft template, and show high reversible capacity and good rate performance as anode for sodium ion battery. And AHMCSs delivers high energy densities of 16.6 and 12.2 Wh kg−1 at the power densities of 250.1 and 9996.4 W kg−1 benefiting from their high surface area and hierarchical porous structure after confined KOH activation. The combination of HMCSs anode and AHMCSs cathode endows the SIHC superior energy densities of 140.1 and 87.1 Wh kg−1 under the power densities of 380.0 and 14249.7 W kg−1, and 80.8% capacitance retention after 4400 cycles at 1 A g−1. Our work provides a new approach for developing high performance sodium storage devices.

In this research study, a self-developed gas seepage experimental system was used to carry out experiments on methane flow with alumina films under different rarefaction degrees conditions, in order to examine the intra-nanopore methane flow law. Then, based on the experimental results under the conditions which considered the slip boundary, a new intra-nanopore methane flow equation with a correction term was established. The change law of the ratio between the equivalent permeability and the Darcy permeability, K p , was studied under the conditions of different rarefaction degrees. The research results showed that the alumina film was a type of ideal material for the study of methane flow law in nanoscale pores. It was found that, with the increase of the rarefaction degree, the ratio between the equivalent permeability and the Darcy permeability, K p , gradually increased. With the increase of the rarefaction degree, multiple flow mechanisms were found to exist in the methane flow, including Darcy flow, slip flow, transition flow, and free molecular flow. The research results provided theoretical support for clearly revealing the flow mechanisms of methane and shale gases.

This paper presents the first transformation of MOFs to polymers without any additives by using a one-step MOF-templated self-polymerization approach. We investigate the conversion process and demonstrate that the MOF-templated self-polymerization is a new and effective approach for the in situ conversion of organic ligands to polymers and even carbon nanomaterials with maintained MOF configurations.

Cuticular waxes cover the plant surface and serve as hydrophobic layer, exhibiting various wax profiles between plant species and plant organs. This paper reports comprehensive analysis of the waxes on organs exposed to air, including leaf, stem, pod pericarp, and petals (banner, wing and keel), and on seed coat enwrapped in pod pericarp of faba bean (Vicia faba). In total 7 classes of wax compounds were identified, including fatty acids, primary alcohols, alkyl esters, aldehydes, alkanes, cinnamyl alcohol esters, and alkylresorcinols. Overall, primary alcohols dominated the waxes on leaves and the seed coat enwrapped in pod pericarp, alkanes accumulated largely in stem and petals, whereas alkylresorcinols were observed in leaf, stem and pod pericarp. Organs exposed to air had higher coverage (>1.2 μg/cm2) than those on seed coat (

We report a unique N/O co-doped urchin-like carbon microspheres (UCMSs) via facile pyrolysis process based on urchin-like polyaniline microspheres (UPMSs) as precursor. UPMSs are obtained through simple self-assembled method without any aided reagent, so the total preparation process of UCMSs is very easy and repeatable. Among three samples, UCMSs-600 shows high lithium storage capacity at 50 mA g−1 (952 mAh g−1) and UCMSs-700 possesses relatively good rate and cycling performance (only 0.026% of attenuation in every cycle at 0.5 A g−1). The correlation between structural parameters (carbon interlayer distance, ordered degree, pore structure and heteroatom doping) and lithium storage features (reversible capacity, rate and cycling performance) of UCMSs with different carbonization temperatures are discussed in detail. And we can obtain the conclusion that designing carbon materials with unique spherical structure and heteroatom-doped feature is a very efficient approach to obtain advanced lithium ion batteries.

Pd nanoparticles with an average size of 1.7 nm confined inside a MIL-100(Fe) cavity (Pd@MIL-100(Fe)) were prepared via double-solvent impregnation combined with a photoreduction process. Due to efficient coupling of photocatalytic dehydrogenation and Pd-based hydrogenation, the resultant Pd@MIL-100(Fe) showed significantly superior performance in light-induced N-alkylation of amines with alcohols over Pd/MIL-100(Fe), in which larger Pd nanoparticles (6–12 nm) deposited on the external surface of MIL-100(Fe) were prepared via a conventional single-solvent impregnation followed by a similar photoreduction process. Kinetic studies and controlled experiments revealed that the whole N-alkylation reaction is limited by the photocatalytic alcohol-to-aldehyde dehydrogenation reaction. This is the first demonstration of light-induced N-alkylation of amines by alcohols over M/MOFs nanocomposites and also highlights the great potential of using M/MOFs nanocomposites as multifunctional catalysts for light-induced organic syntheses.

CPO-27-Mg (also referred to as Mg2(DOBDC), DOBDC = 2,5-dioxido-1,4-benzenedicarboxylate), a Mg2+ based metal-organic framework which shows the highest CO2 uptake among the already reported MOF materials, was chosen to combine with TiO2 to form CPO-27-Mg/TiO2 nanocomposite via a hydrothermal self-assembly method. The as-obtained CPO-27-Mg/TiO2 nanocomposite is composed of TiO2 nanospheres on the spindle-shaped CPO-27-Mg microcrystal. Intimate contact between CPO-27-Mg and TiO2 nanospheres exists due to the coordination between the carboxylate groups in DOBDC and Ti4+ in TiO2. The as-obtained CPO-27-Mg/TiO2 nanocomposite exhibited enhanced performance for the photocatalytic CO2 reduction to form CO and CH4 due to its high adsorption capacity toward CO2 and the existence of open alkaline metal sites in CPO-27-Mg. By incorporating MOFs with open alkaline metal center into TiO2, the reduction of H2O to H2, a competitive reaction to photocatalytic CO2 reduction, was totally inhibited. This study highlights the promising prospect of incorporating MOFs with open alkaline metal sites into semiconductors for artificial CO2 photo-conversion.

SiCf/BNNTs–SiC hierarchical composites were fabricated via firstly in situ growth of boron nitride nanotubes (BNNTs) on the surface of silicon carbide (SiC) fibers using boron powder as a raw material and subsequently matrix densification by chemical vapor infiltration (CVI) and polymer impregnation/pyrolysis (PIP) methods. With the incorporation of BNNTs, energy dissipation mechanisms at the nanoscale triggered by BNNTs such as pullout, debonding, crack deflection and crack bridging are observed. But the positive effect of BNNTs on mechanical properties have not been raised due to the offset from the negative effect of pores in composites. Additionally, the residual boron powder results in an improved oxidation resistance and parabolic oxidation kinetics of SiCf/SiC composites at 900 °C, thanks to the protective effect of the B2O3 glassy phase formed by the oxidation of boron. Consequently, a better strength retention after oxidation is obtained. Moreover, it is believed that the remaining strengthening and toughening mechanisms aroused by BNNTs surviving after oxidation probably also make a contribution to the better strength retention.

A facile and effective photo-reduction approach to deposit Pt nanoparticles on MIL-100(Fe) by using a metal–organic framework (MOF) itself as a photoactive catalyst has been developed. The synthesized samples were characterized using X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) and determining N2-sorption BET surface area. The as-obtained Pt/MIL-100(Fe) showed photocatalytic activity for H2 evolution under visible light irradiation and its performance is superior to that of Pt/MIL-100(Fe)–NaBH4, in which Pt was obtained via reduction by NaBH4. This work provides an effective and facile approach for the preparation of metal nanoparticles/MOF nanocomposites and demonstrates their potential in solar energy transformations.

Covalent triazine-based frameworks (CTFs), as a type of 2D conjugated polymer, have attracted keen attention because of the promising visible-light-driven photocatalytic performance for water splitting. Nonetheless, amelioration on the configuration and electronic microstructure of CTFs for enhanced photocatalytic performance is still challenging and anticipated. Herein, we developed a new strategy to synthesize visible-light-driven Cl-intercalated CTF-1 photocatalysts (labeled as Cl-ECF) via a ball-milling exfoliation-assisted acidification method. Many characterizations confirm the formation of Cl-C and Cl-N bonds in the Cl-ECF. The effects of the Cl-intercalation on the crystal structure, microstructure and charge transfer behaviors of CTF-1 were systematically studied by various characterizations and DFT calculation. The results revealed that Cl-ECF exhibited significantly promoted charge transfer, narrowed bandgap and enhanced photocatalytic activity of H2 production because Cl-C and Cl-N covalent bonds can form covalently interlayer channels in the Cl-ECF. The as-prepared Cl-ECF shows a hydrogen production rate of 1.296 mmol·g–1 h–1 under visible light irradiation, which is 2.2 times higher than that of CTF-1. This work could provide new insights into the new approach of intercalation modification to improve photocatalytic performance of 2D layered photocatalysts.

Nowadays, Silicon (Si) is known as the next generation anode of lithium ion batteries (LIBs), owing to its high theoretical capacity, low lithium storage potential and natural abundance. However, the huge volume expansion and poor conductivity of silicon anodes restrict their practical application due to their poor cyclability and unsatisfied rate performances. Herein, to improve the electrochemical performance of silicon anodes, a facile one-step injection pyrolysis was used to construct a novel secondary conductive and buffer structure where Si nanoparticles are conformally coated by the interconnected onion-like carbon and then are anchored in graphene nanosheets (GNS) skeleton. The synergy of interconnected ordered onion-like carbon coating layer and GNS favors for promoting fast electron transfers and improving electrochemical kinetics, which benefits for achieving an excellent rate performance. Additionally, layer-by-layer strain relaxation by onion-like carbon and flexible GNS hierarchically buffer the substantial variation in volume of Si and then endow the composite with good cyclability. Specifically, the anode of GNS@OLC-Si shows high reversible capacity of 1129.3 mAh g−1 after 300 cycles at a current density of 0.5 A g−1. In rate performance test, the capacity retention of the GNS@OLC-Si is high especially at high current density (66.2% at 2 A g−1). Hence, a new secondary structure is successfully designed to accelerate the diffusion kinetics and buffer the volume change of Si, thereby achieving stable cyclabilities and rate performances.

Porous carbon (PC) materials are the excellent alternative to anodes of high performance sodium ion batteries (SIBs). However, most PC materials are prepared with complicated and multi-step template method, which limits the mass production. Herein, we present a simple and repeatable calcination approach to synthesize three-dimensional porous carbon (3D-PC) materials using poly(p-phenylenediamine) hydrogel as precursor. N, O and P heteroatoms are successfully introduced into 3D-PC to provide more sodium storage sites. The obtained 3D-PC delivers high sodium storage capacity of 332 mAh g−1 at 50 mA g−1 and the reversible capacity still retains 139 mAh g−1 at 10 A g−1. Moreover, 3D-PC also shows ultralong cycling life, the stable capacities of 212 mAh g−1 and 120 mAh g−1 after 1000 cycles even at the high current density of 0.5 A g−1 and 5 A g−1, respectively. These results illustrate that 3D-PC electrode displays great rate capability and excellent cycling stability, which would be ascribed to surface-dominated sodium storage mechanism according to quantitative analysis. This method is low cost and effective for preparing high-performance porous carbon anodes for SIBs.

Droughts not only reduce the biomass of sorghum (Sorghum bicolor (L.) Moench) but also increase the risk of hydrogen cyanide (HCN) toxicity to animals, mainly due to increased HCN content in drought-stressed plants. In the present study, the variations of HCN contents in 12 sorghum genotypes (10 sweet sorghum cultivars, one Sudangrass and one forage sorghum) were investigated at jointing, filling and ripening stages under rainfed conditions. Next, three genotypes – one sweet sorghum, one Sudangrass and one forage sorghum – were further selected to elucidate the physiological mechanisms of plant growth regulators (PGRs) (abscisic acid (ABA) and methyl jasmonate (MeJA)) in mitigating the concentrations of HCN in drought-stressed plants in a pot experiment. About 100 µg/L ABA and 100 µg/L MeJA were sprayed separately or together twice on drought-stressed (50 and 75% field water capacity) plant leaf. The drought lasted for 15 days. In the field experiment the HCN content in plants reduced from jointing to filling stages then increased from filling to ripening stages in several cultivars. In the pot experiment, drought increased the HCN accumulation and soluble protein content in leaves of all three genotypes. PGRs overall reduced the HCN contents in drought-stressed sweet sorghum and Sudangrass but not in forage sorghum (except in the ABA+MeJA treatment). However, the soluble protein contents were reduced by PGRs in drought-stressed forage sorghum but not in sweet sorghum (except in the ABA+MeJA treatment) and Sudangrass. Both ABA and MeJA increased the plant weights, whereas only MeJA enhanced net photosynthetic rate (PN) in all three genotypes. PGRs reduced release rate of superoxide and hydrogen peroxide and malondialdehyde in all drought-stressed plants, and reduced the activities of peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase in sweet sorghum but not in other two genotypes. These results suggest that exogenous ABA and MeJA could increase plant weight and reduce HCN content in drought-stressed sorghums, with varying physiological responsive mechanisms among sorghum genotypes.

Herein, a facile and efficient strategy was proposed to design and synthesize novel isotypic heterojunctions (CN-T/CN-M) based on graphitic carbon nitride (CN) derived from different monomers via cross-linking reaction with organic linkers. DFT calculations and transient spectra analyses elucidated that integration of single CN layers via chemical amide condensation can not only reduce the defective -NH2 groups that act as charge recombination sites but also extend the large delocalized π-electron systems, leading to a suitable internal electric field to efficiently promote migration of photogenerated carriers. Consequently, compared with the individual CN components and their heterostructure prepared by conventional method, CN-T/CN-M shows superior photocatalytic activity of H2 evolution and higher stability under visible light irradiation. Furthermore, an enhanced photocatalytic mechanism was proposed. This work develops a new avenue via covalent cross-linking reaction to construct efficient and stable heterostructured catalysts and provides new idea to design isotypic heterojunction with excellent photocatalytic performance.

Introduction Rice bean (Phaseolus calcaltus), as an annual summer legume, is always subjected to acid soils in tropical to subtropical regions, limiting its growth and nodulation. However, little is known about its responses to lime and biochar addition, the two in improving soil fertility in acid soils. Materials and Methods In the current study, a pot experiment was conducted using rice bean on a sandy yellow soil (Orthic Acrisol) with a pH of 5.5. The experiment included three lime rates (0, 0.75 and 1.5 g kg−1) and three biochar rates (0, 5 and 10 g kg−1). The biochar was produced from aboveground parts of Solanum tuberosum using a home-made device with temperature of pyrolysis about 500 °C. Results and Discussion The results indicated that both lime and biochar could reduce soil exchange Al concentration, increase soil pH and the contents of soil microbial biomass carbon and microbial biomass nitrogen, and enhance urease and dehydrogenase activities, benefiting P. calcaltus growth and nodulation in acid soils. Lime application did decrease the concentrations of soil available phosphorus (AP) and alkali dispelled nitrogen (AN), whereas biochar application increased the concentrations of soil AP, AN and available potassium (AK). However, sole biochar application could not achieve as much yield increase as lime application did. High lime rate (1.5 g lime kg−1) incorporated with low biochar rate (5 g biochar kg−1) could obtain higher shoot biomass, nutrient uptake, and nodule number when compared with high lime rate and high biochar rate. Conclusion Lime incorporated with biochar application could achieve optimum improvement for P. calcaltus growing in acid soils when compared with sole lime or biochar addition.

The mucilage polysaccharides from Dioscorea opposita (DOMP) were extracted and treated with a single/dual enzymatic hydrolysis. The characterisation and viscosity were subsequently investigated in this study. DOMP obtained 62.52% mannose and 23.45% glucose. After single protease and trichloroacetic acid (TCA) treatments, the mannose content was significantly reduced to 3.96%, and glucose increased from 23.45% to 45.10%. Dual enzymatic hydrolysis also decreased the mannose and glucose contents to approximately 18%-35% and 7%-19%, respectively. The results suggest that enzymatic degradation could effectively remove the protein from DOMP accompanied by certain polysaccharides, especially mannose. The molecular weight, surface morphology, viscosity and particle sizes were measured. Enzymatic hydrolysis reduced molecular weight, decreased the viscosity, and increased the particle sizes, which indicates that the characterisations of DOMP samples were altered as structures changed. This study was a basic investigation into characterisation of DOMP to contribute to the processing of food by-products.

Phenol is one of the most important chemicals in industry. One-step selective benzene hydroxylation is an attractive yet challenging method for phenol production, especially when such a reaction can be driven by solar energy. Herein, we reported that a highly selective benzene hydroxylation to phenol can be achieved over two Fe-based metal–organic frameworks [MIL-100(Fe) and MIL-68(Fe)] under visible light irradiations using hydrogen peroxide (H2O2) as an oxidant. An optimal benzene conversion of 30.6% was achieved with a H2O2:benzene ratio of 3:4 over MIL-100(Fe) after 24 h irradiations. ESR results and the kinetic studies suggested that a successful coupling of the photocatalysis of Fe–O clusters in Fe-based metal–organic frameworks (MOFs) with a Fenton-like route is involved in this benzene hydroxylation process. The comparison of the reaction over MIL-100(Fe) and MIL-68(Fe) reveals that the structure of MOFs significantly influences the photocatalytic efficiency. Because the composition and the struct...

It is highly desirable to convert CO2 to valuable fuels or chemicals by means of solar energy, which requires CO2 enrichment around photocatalysts from the atmosphere. Here we demonstrate that a porphyrin-involved metal-organic framework (MOF), PCN-222, can selectively capture and further photoreduce CO2 with high efficiency under visible-light irradiation. Mechanistic information gleaned from ultrafast transient absorption spectroscopy (combined with time-resolved photoluminescence spectroscopy) has elucidated the relationship between the photocatalytic activity and the electron-hole separation efficiency. The presence of a deep electron trap state in PCN-222 effectively inhibits the detrimental, radiative electron-hole recombination. As a direct result, PCN-222 significantly enhances photocatalytic conversion of CO2 into formate anion compared to the corresponding porphyrin ligand itself. This work provides important insights into the design of MOF-based materials for CO2 capture and photoreduction.

Tandem reactions, which enable multistep reactions in one pot, offer enormous economical advantages. For the first time, this manuscript reported that NH2-MIL-101(Fe), an earth abundant Fe-containing MOF material, can catalyze efficiently the one-pot reaction between aromatic alcohols and active methylene compounds via a tandem photo-oxidation/Knoevenagel condensation under visible light and at room temperature. NH2-MIL-101(Fe) acts as a photocatalyst for the oxidation of aromatic alcohols to aldehydes as well as a base catalyst for Knoevenagel condensation between the as-formed aldehydes and the active methylene compounds. The comparison of the reactions over NH2-MIL-101(Fe) and another two MOFs (NH2-UiO-66(Zr) and NH2-MIL-125(Ti)) reveals that the strength of the basic sites in the MOFs influences significantly the efficiency of the tandem reaction. This study highlights the great potential of MOFs as multifunctional photocatalysts for one-pot tandem reactions.

[EN] MIL-100(Fe) and MIL-68(Fe), two Fe-based MOFs, were found to be active for oxidative condensation between alcohols and o-aminothiophenols to form 2-substituted benzothiazoles under visible light irradiation using oxygen (02) as oxidant. This reaction can be applied to a wide range of substrates with medium to high yield. Controlled experiments and ESR results revealed a superoxide radical (O-2(center dot-))-mediated pathway, which is derived from the reduction of O-2 by photogenerated Fe2+ on Fe-O clusters. The whole multistep reaction is limited by the step of the photo-oxidation of alcohols to aldehydes. MIL-100(Fe) showed catalytic performance superior to that of MIL-68(Fe) because its higher concentration of long-lived (mu s time scale) positive holes can be photogenerated over MIL-100(Fe), in contrast to MIL-68(Fe). This study not only provides an economical, sustainable, and thus green process for the production of 2-substituted benzothiazoles, but also illustrates the potential of using transient absorption spectroscopy as an important tool for understanding the photophysics of MOFs, which are believed to show great potential as multifunctional catalysts for light-induced organic transformations. (C) 2017 Elsevier Inc. All rights reserved., This work was supported by the 973 Program (2014CB239303), the NSFC (21273035), the National Key Technologies R&D Program of China (2014BAC13B03), and an Independent Research Project of the State Key Laboratory of Photocatalysis on Energy and Environment (2014A03). Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-1-R) is also gratefully acknowledged. Z. Li thanks the Award Program for Minjiang Scholar Professorship for financial support.

The utilization of solar energy for the conversion of CO2 into valuable organic products is one of the best solutions to solve the problems of global warming and energy shortage. The development of photocatalysts capable of reducing CO2 under visible light, especially those containing earth-abundant metals, is significant. Herein we report that a series of earth-abundant Fe-containing MOFs (MIL-101(Fe), MIL-53(Fe), MIL-88B(Fe)) show photocatalytic activity for CO2 reduction to give formate under visible light irradiation. The direct excitation of the Fe–O clusters in these MOFs induces the electron transfer from O2– to Fe3+ to form Fe2+, which is responsible for the photocatalytic CO2 reduction. Among the three investigated Fe-based MOFs, MIL-101(Fe) showed the best activity due to the existence of the coordination unsaturated Fe sites in its structure. All three amine-functionalized Fe-containing MOFs (NH2-MIL-101(Fe), NH2-MIL-53(Fe) and NH2-MIL-88B(Fe)) showed enhanced photocatalytic activity in compari...

Experimental system for investigating gas-desorption characteristics of deformed coal was established. The gas desorption law of deformed coal with different damage extent was investigated. The desorption characteristics of deformed coal having different size under different equilibrium pressures were determined. This provides a theoretical basis for the prediction of coal and gas outburst, the measurement of pressure and content of coal seam gas, and the estimation of gas emission of coal mining fell.

Metal-organic framework (MOF) NH2 -Uio-66(Zr) exhibits photocatalytic activity for CO2 reduction in the presence of triethanolamine as sacrificial agent under visible-light irradiation. Photoinduced electron transfer from the excited 2-aminoterephthalate (ATA) to Zr oxo clusters in NH2 -Uio-66(Zr) was for the first time revealed by photoluminescence studies. Generation of Zr(III) and its involvement in photocatalytic CO2 reduction was confirmed by ESR analysis. Moreover, NH2 -Uio-66(Zr) with mixed ATA and 2,5-diaminoterephthalate (DTA) ligands was prepared and shown to exhibit higher performance for photocatalytic CO2 reduction due to its enhanced light adsorption and increased adsorption of CO2 . This study provides a better understanding of photocatalytic CO2 reduction over MOF-based photocatalysts and also demonstrates the great potential of using MOFs as highly stable, molecularly tunable, and recyclable photocatalysts in CO2 reduction.