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With the in-depth research of sodium-ion batteries (SIBs), the development of novel sodium-ion anode material has become a top priority. In this work, tube cluster-shaped SbPS4 was synthesized by a high-temperature solid phase reaction. Then the typical short tubular ternary thiophosphate SbPS4 compounded with graphene oxide (SbPS4/GO) was successfully synthesized after ultrasonication and freeze-drying. SbPS4 shows a high theoretical specific capacity (1335 mAh/g) according to the conversion-alloying dual mechanisms. The unique short tube inserted in the spongy graphene structure of SbPS4/GO results in boosting the Na ions transport and alleviating the huge volume change in the charging and discharging processes, improving the sodium storage performance. Consequently, the tubular SbPS4 compounded with 10% GO provides an outstanding capacity of 359.58 mAh/g at 500 mA/g. The result indicates that SbPS4/GO anode has a promising application potential for SIBs.

CoSe-SC@NC as an advanced anode for SIBs have been reported in this work, it exhibits excellent electrochemical performance. Meanwhile, the improved sodium storage mechanism is further analyzed by in situ XRD and ex situ HRTEM.

With the rapid development of electronic technology, the demand for thermal management materials is increasing continuously. Recent years graphene paper is considered as a potential material to replace the traditional graphitized polyimide film. Although the current route to graphene paper can achieve a high thermal conductivity, the extremely high energy consumption in graphitization procedure and severe heavy metal contamination limit the application of graphene paper. Here we develop a high-efficiency, low-energy cost, and inexpensive technology to produce graphene paper in large quantities. Without graphitization, the thermal conductivity of this graphene laminated film can reach 975 W m−1 K−1 when the thickness of film is 65 μm. Based on this easy-operated technology, we have already completed the pilot plant test, attained capacity of 3 kg graphene per reactor in 8 h and 800 mm × 100 m of graphene film each roll which was continuously and macroscopically assembled on our self-made equipment.

Development of efficient and robust electrode materials is significant for sodium-ion batteries (SIBs). Metallic selenides have been widely investigated as a promising anode material based on their relatively high theoretical capacity. However, rapid capacity fading and huge volume changes greatly hinder their practical application. Herein, for the first time, uniform yolk-shell Fe7Se8@C/N nanoboxes (Fe7Se8@C/N NBs) with the Fe7Se8 cores completely embedded by a thin and robust carbon shell are prepared using a strategy of facile etching method combined with selenization for advanced anode materials for SIBs. Benefiting from the unique structural merits, the Fe7Se8@C/N NBs electrodes for Na-ion half cells exhibit high Na-ion storage capacity (385.5 mAh g−1 at 0.1 A g−1) and superior rate performance (316.0 mAh g−1 at 5 A g−1) as well as impressive cyclability with no capacity decay over 1000 cycles. The sodium storage mechanism of Fe7Se8@C/N NBs electrode is systematically studied with the aid of ex-situ X-ray diffraction and transmission electron microscopy. Finally, the assembled full cells coupled with the lab-made high-voltage Na3V2(PO4)2O2F cathode and Fe7Se8@C/N NBs anode materials show superior energy-storage performance.

The introduction of certain structures or functional groups on benzothiazole and its derivatives containing a benzene ring and a thiazole ring can be used to construct benzothiazole fluorescent probes. Based on the mechanism of photoinduced electron transfer, excited-state intramolecular proton transfer (ESIPT), intramolecular charge transfer, aggregation-induced emission, the obtained fluorescent probes can specifically interact with the analyte, thereby changing their luminescence characteristics to achieve the detection of the analyte. Benzothiazole fluorescent probes can be applied to the detection of substances, the analysis of harmful substances and cell imaging. In this paper, the research situation of benzothiazole fluorescent probes in the past 5 years is reviewed, and it is mainly divided into metal ions, anions, small molecules and biological macromolecules according to the types of analytes. In the conclusion, the current challenges and further applications of benzothiazole fluorescent probes are analyzed. Application of detection and analysis of benzothiazole fluorescent probes.

Transition metal oxides have vastly limited practical application as electrode materials for lithium-ion batteries (LIBs) due to their rapid capacity decay. Here, a versatile strategy to mitigate the volume expansion and low conductivity of Fe3 O4 by coating a thin carbon layer on the surface of Fe3 O4 nanosheets (NSs) was employed. Owing to the 2D core-shell structure, the Fe3 O4 @C NSs exhibit significantly improved rate performance and cycle capability compared with bare Fe3 O4 NSs. After 200 cycles, the discharge capacity at 0.5 A g-1 was 963 mA h g-1 (93 % retained). Moreover, the reaction mechanism of lithium storage was studied in detail by ex situ XRD and HRTEM. When coupled with a commercial LiFePO4 cathode, the resulting full cell retains a capacity of 133 mA h g-1 after 100 cycles at 0.1 A g-1 , which demonstrates its superior energy storage performance. This work provides guidance for constructing 2D metal oxide/carbon composites with high performance and low cost for the field of energy storage.

Thermally reversible self-healing polymer (SHP) electrolyte membranes are obtained by Diels-Alder cycloaddition and electrolyte embedding. The SHP electrolytes membranes are found to display high ionic conductivity, suitable flexibility, remarkable mechanical properties and self-healing ability. The decomposition potential of the SHP electrolyte membrane is about 4.8 V (vs. Li/Li+) and it possesses excellent electrochemical stability, better than that of the commercial PE film which is only stable up to 4.5 V (vs. Li/Li+). TGA results show that the SHP electrolyte membrane is thermally stable up to 280 °C in a nitrogen atmosphere. When the SHP electrolyte membrane is used as a separator in a lithium-ion battery with an LCO-based cathode, the SHP membrane achieved excellent rate capability and stable cycling for over 100 cycles, and the specific discharge capacity could be almost fully recovered after self-healing. Furthermore, the electrolyte membrane exhibits excellent electrochemical performance, suggesting its potential for application in lithium-ion batteries as separator material.

Carbon dots (CDs) are carbon-based quasi-spherical fluorescent nanoparticles with unique physical and chemical properties. Due to their complexity and diversity, CDs are applied in analytics, sensors, bio-imaging and diagnostics. Stabilizing CDs as well as improving their performances can extend their range of applications; it is desirable to combine them in an appropriate solid matrix or prepare solid-state nanocomposites. In this review, a summary of the research of CD nanocomposites is given. Describes the loading methods of CDs on polymers, metals and their compounds, non-metals and their compounds, and metal organic frameworks, which including electrostatic interactions, covalent bonds, non-covalent bonds or hydrogen bonds. In addition, the working mechanism and application of CD nanomaterials are also introduced. The challenges encountered, potential and prospects with CD nanocomposite are discussed at the end of the article.

We designed two stable monolayers of Ca2NOH and Y2C(OH)2 through replacing the anionic electrons with negatively charged hydroxide ions. Calculation results indicate that these two monolayers are dynamic and thermodynamic stable. Ca2NOH is determined as an indirect semiconductor with band gap of 1.51 eV based on hybrid functional calculations, while Y2C(OH)2 possesses a direct band gap of 0.72 eV. Moreover, to investigate the potential applications of Ca2NOH and Y2C(OH)2 monolayers, we studied the adsorption and diffusion performance of Li, Na and Mg atoms on their surfaces. The calculated adsorption energies, differential charge density and Bader charge analysis reveal that Li, Na and Mg atoms could anchor on Ca2NOH and Y2C(OH)2 surfaces. Nudged Elastic band calculation results suggest that the barriers for Li, Na, and Mg diffusion on Ca2NOH surface are 0.79 eV, 0.42 eV and 0.42 eV. While Y2C(OH)2 monolayer exhibits relative low diffusion barriers of 0.60 eV, 0.26 eV and 0.10 eV for Li, Na and Mg, respectively and their corresponding diffusion coefficients are as large as 1.52 × 10−18, 1.52 × 10−12 and 1.52 × 10−8 m2/s. The diffusion barriers and diffusion coefficients. The appropriate adsorption energies, low diffusion barriers and relative large diffusion coefficients of Na/Mg atoms imply that Ca2NOH and Y2C(OH)2 monolayers are promising electrode materials for the corresponding metal-ion batteries. All the results serves to modify, stabilize and understand two dimensional electrides and put their properties into practical use.

To improve the energy and power densities of carbon-based supercapacitors, more attentions are currently focused on increasing the specific surface area and optimizing the pore size distribution of carbon materials. However, only few researchers are devoted to investigate the effect of surface treatment and electrolyte-wetting on the properties of supercapacitors. Here, phytic acid (PA) is selected as the medium to tune the wettability of graphene hydrogel (GH) to further investigate the effect of wettability on capacitance performance. The PA molecules on PA modified graphene hydrogel (PAGH) play a significant role in ion-inner diffusion and electrosorption onto electrically charged surface. The contribution of pseudocapacitance and double-layer capacitance increased with the content of PA due to the increased redox groups and enlarged electrolyte accessible area. Graphene electrodes with high mass loadings can be prepared by stamping the PAGH slices onto stainless steel mesh. These electrodes can further be assembled into wearable all-solid-state supercapacitors with high volumetric energy density (7.98 mWh cm−3 at 25 mW cm−3 and 5.63 mWh cm−3 at 2.5 W cm−3). In addition, the hydrogel slices can be used as the pixel elements for stamping desired patterns for wearable applications. It provides a new route to meliorate the capacitance performance of carbon-based all-solid-state supercapacitors.

Combining electrode materials with low-dimensional carbonaceous materials such as graphene is an effective way to improve the electrochemical performance of sodium/lithium-ion batteries (SIBs/LIBs). A common drawback of these recombinant hybrids is the weak interaction between the active component and graphene, resulting in poor structural stability and high resistance to diffusion of Na+/Li+ and electrons diffusing between phase boundaries during charging and discharging, thus leading to capacity decay and low rate capability of these hybrids. Here, a facile integrated construction strategy based on Schiff base reactions is developed to build a nitrogen and sulfur co-doped flexible lotus-leaf-like carbon and FeS nanosheets (FeS@N,S-CNSs). This structure takes full advantage of the high conductivity and mechanical flexibility of carbon nanosheets, and the high theoretical capacity of FeS. Together with the co-doping effects, the nanoscale size of FeS, and the robust connection between the in-situ generated FeS nanocrystals and carbon nanosheets, the FeS@N,S-CNSs outputs excellent electrochemical performance in both of SIBs and LIBs. Impressively, experimental results and Density functional theory (DFT) calculations indicate that the charging/discharging process is essentially dominated by pseudocapacitive behavior, this intrinsic feature gives FeS@N,S-CNSs electrode exceptional rate capability (∼50% capacity retention even at 100 A g−1 in SIBs).

Broad spectrum absorption of semiconductor photocatalysts is an essential requirement to achieve the best values of solar energy utilization. Here, through precise surface state adjustment, coaxial tri-cubic Ag0/AgCl materials with distinct apparent colours (blue and fuchsia) were successfully fabricated. The reasons for the different colour generation of the Ag0/AgCl materials were investigated by performing corresponding spectrum analysis. It was revealed that Ag0/AgCl-blue and Ag0/AgCl-fuchsia crystals could efficiently boost the photon energy harvesting, spanning from the UV to near-infrared spectral region (250–800 nm), and achieved 2.6 and 5.4 times the wastewater degradation efficiency of AgCl-white. Simultaneously, these two fresh coloured candidates were demonstrated to have preferable photocatalytic CO2 photoreduction capability, with yields of ∼3.6 (Ag0/AgCl-fuchsia) and 2.6 (Ag0/AgCl-blue) times that of AgCl-white. It is expected that this work will provide a beneficial perspective for understanding the solar absorption feature at both the major structure modulation and particular surface state regulation level.

Summary: The development of high-performance cathodes for sodium-ion batteries (SIBs) is one key issue required for the success of large-scale energy storage systems. In addition to performance degradation during cycling, electrode materials are usually hampered by instability when stored in various environments severely restricting their practical application. Here, we report a stable cathode material that shows no obvious capacity attenuation in various storage conditions. The cathode is composed of regular and homogeneous Na3V2(PO4)2O2F0.99Cl0.01 (NVPFCl) microcubes, with electrochemical properties, including high specific capacity (128.2 mA h g-1 at 0.1 C), excellent rate capability (79.8 mA h g-1 at 20 C), long-term cycle life, and all-climate performance. Studies using in/ex situ characterization and electrode kinetics are implemented to reveal the possible reasons for the stability and electrochemical activity of NVPFCl. This work may provide a pathway for the development of all-climate and storage-stable SIB cathode materials.

With the rapidly increasing use of lithium ion batteries (LIBs), the corresponding spent materials will eventually lead to severe environment pollution and resource waste if they cannot be recycled...

There are still many problems that hinder the development of sodium-ion batteries (SIBs), including poor rate performance, short-term cycle lifespan, and inferior low-temperature property. Herein, excellent Na-storage performance in fluorophosphate (Na3 V2 (PO4 )2 F3 ) cathode is achieved by lattice regulation based on charge balance theory. Lattice regulation of aliovalent Mn2+ for V3+ increases both electronic conductivity and Na+ -migration kinetics. Because of the maintaining of electrical neutrality in the material, aliovalent Mn2+ -introduced leads to the coexistence of V3+ and V4+ from charge balance theory. It decreases the particle size and improves the structural stability, suppressing the large lattice distortion during cathode reaction processes. These multiple effects enhance the specific capacity (123.8 mAh g-1 ), outstanding high-rate (68% capacity retention at 20 C), ultralong cycle (only 0.018% capacity attenuation per cycle over 1000 cycles at 1 C) and low-temperature (96.5% capacity retention after 400 cycles at -25 °C) performances of Mn2+ -induced Na3 V1.98 Mn0.02 (PO4 )2 F3 when used as cathode in SIBs. Importantly, a feasible sodium-ion full battery is assembled, achieving outstanding rate capability and cycle stability. The strategy of aliovalent ion-induced lattice regulation constructs cathode materials with superior performances, which is available to improve other electrode materials for energy storage systems.

Integration of the contradictory attributes of a well-aligned pore structure and excellent electrical/mechanical properties into graphene-based macroscopic materials perfectly for wearable and portable electronics and energy devices is still a big challenge hitherto. In this study, a simple yet highly efficient reduction and evaporation co-induced self-assembly (RES) method was successfully developed to prepare self-crosslinking Janus graphene films with well-aligned pore and dense shell structures, which endowed the material with excellent electrical conductivity and good mechanical property. Electrochemical studies demonstrate that the graphene films with a thickness of 12.4 μm exhibit an extraordinary volumetric capacitance of 127.7 F cm−3 at a current density of 0.5 mA cm−2, which is superior to that reported in most of the previous studies. The flexible all-solid state supercapacitor based on the Janus graphene films exhibits an ultrahigh energy density of 2.78 mW h cm−3 at 40.3 mW cm−3 as well as a remarkable cycling performance (95.5% of initial capacitance is retained after 10 000 cycles at 2 mA cm−2). The fatigue tests further confirm the preferable flexibility and bending and folding capability of the proposed supercapacitor; these are crucial factors to be considered for further wearable applications. These tough and durable supercapacitor devices connected in series have been successfully well-designed into wearable energy storage systems to power small gadgets such as electronic watches and light-emitting diodes. In addition, the microgels formed during the film preparation process are helpful as microgel films can be engraved into micro-supercapacitor patterns that can work as an integrated photodetection system. This strategy can be potentially applied for the design and fabrication of new flexible and portable graphene-based wearable electronic devices.

The discovery of graphene and other two-dimensional (2D) materials has set the foundation for exploring and designing novel single layered sheets. The family of 2D materials encompasses a wide selection of compositions including almost all the elements of the periodic table and they have the potential to play a fundamental role in the future of electronics, composite materials and energy technology. Therefore, searching for new 2D materials is a big challenge in materials science. In this work, we theoretically designed a monolayer of Ti3BN following the strategy of “atomic transmutation”. The Ti3BN monolayer can be considered as three Ti-atomic layers being interleaved with one N-atomic layer and one B-atomic layer, in the sequence of Ti1–N–Ti2–B–Ti3. The moderate cohesive energy, positive phonon frequencies and high melting point are the best guarantees for good stability of Ti3BN. Based on a global minimum structures search using the particle-swarm optimization (PSO) method, Ti3BN is the lowest energy structure in 2D space, which holds great promise for the realization of layered Ti3BN in experiment. Based on density functional theory (DFT) calculations, Ti3BN is intrinsically metallic and its electronic properties can be modulated by varying the surface groups, such as OH or F-termination. If realized in experiment, it may find applications in many aspects.

Collector and binder-free high quality graphene film has been successfully synthesized by a simple filtration process. Electrochemical results indicate that the graphene film exhibits good rate and cycle behavior compared with the commercial mesocarbon microbeads (MCMB)/copper system. More importantly, after excluding the dead-weight copper collector, the gravimetric energy density could be enhanced to some extent. This may provide an alternative in the demand for higher energy density lithium-ion batteries.

Metallic selenides have been widely investigated as promising electrode materials for metal-ion batteries based on their relatively high theoretical capacity. However, rapid capacity decay and structural collapse resulting from the larger-sized Na+ /K+ greatly hamper their application. Herein, a bimetallic selenide (MoSe2 /CoSe2 ) encapsulated in nitrogen, sulfur-codoped hollow carbon nanospheres interconnected reduced graphene oxide nanosheets (rGO@MCSe) are successfully designed as advanced anode materials for Na/K-ion batteries. As expected, the significant pseudocapacitive charge storage behavior substantially contributes to superior rate capability. Specifically, it achieves a high reversible specific capacity of 311 mAh g-1 at 10 A g-1 in NIBs and 310 mAh g-1 at 5 A g-1 in KIBs. A combination of ex situ X-ray diffraction, Raman spectroscopy, and transmission electron microscopy tests reveals the phase transition of rGO@MCSe in NIBs/KIBs. Unexpectedly, they show quite different Na+ /K+ insertion/extraction reaction mechanisms for both cells, maybe due to more sluggish K+ diffusion kinetics than that of Na+ . More significantly, it shows excellent energy storage properties in Na/K-ion full cells when coupled with Na3 V2 (PO4 )2 O2 F and PTCDA@450 °C cathodes. This work offers an advanced electrode construction guidance for the development of high-performance energy storage devices.

A lot of research attention has been paid to designing and exploring efficient adsorbents for HCHO adsorption and decomposition. Herein, we have demonstrated a highly active material, WC, for HCHO adsorption through first-principles calculations. Due to the exposed three-coordinated W atoms (W3c) of the WC (0001) surface, HCHO molecules can be settled on the WC (0001) surface through newly formed OF–W3c and/or CF–W3c bonds, forming different adsorption configurations. When settled on the WC (0001) surface, the molecular configuration of the HCHO molecule and the corresponding CF–HF and CF–OF bond lengths would be greatly changed. Due to the enlarged CF–HF and CF–OF bond lengths, the adsorbed HCHO molecules tend to dissociate through two possible pathways; these are the two-step CF–HF bond scission or the one-step CF–OF bond scission. The former results in two H adatoms and a CO molecule chemisorbed to the surface and the latter produces an O adatom and a CH2 group on the surface. Further Cl-NEB calculations demonstrate that the pre-adsorbed O atom has little influence on the first CF–HF bond scission and the CF–OF bond scission, while promoting the second CF–HF bond scission. Considering the dissociative products, H and CH2 have the potential to couple into a CH3 group (or even a CH4 molecule) and two CH2 groups may couple into a C2H4 molecule. In the end, we propose that OH ions may couple with the dissociative products of HCHO, so an alkali solution could be used to post-process the WC (0001) surface to restore its surface active sites. These results demonstrated the potential of WC in HCHO sensing and abatement.

A novel high capacity cathode material with a full concentration-gradient (FCG) structure has been successfully synthesized by a modified hydroxide co-precipitation method. A continuous concentration change of Ni, Co, and Mn from the core LiNi0.8Co0.1Mn0.1O2 to the shell LiNi0.4Co0.2Mn0.4O2 in each particle with an average composition of LiNi0.6Co0.15Mn0.25O2 is confirmed by EDX and ICP, respectively. Charge–discharge tests demonstrate that the FCG cathode delivers a high specific capacity of 190 mA h g−1 at a current density of 0.05 mA cm−2, exceptional rate capacity (a high capacity of 125 mA h g−1 at an ultrafast rate of 10C-rate), and an ultralong cycle life up to 1000 cycles (capacity retention of 80% at 5C-rate), which is obviously superior to the conventional cathode LiNi0.6Co0.15Mn0.25O2. Meanwhile, the Mn-rich in the outer layer of the FCG cathode contributes to more excellent thermal stability than the conventional cathode LiNi0.6Co0.15Mn0.25O2.

Three different types of spherical cathodes (Li[Ni0.6Co0.2Mn0.2]O2) were synthesized via hydroxide co-precipitation method coupled with high temperature lithiation process. The particle size, nanostructure, specific surface area and pore distributions can be controlled as expected. X-ray diffraction patterns revealed that the as-obtained cathode materials had a typical hexagonal α-NaFeO2 layered structure with a space group Rm. The electrochemical measurements demonstrate that Li[Ni0.6Co0.2Mn0.2]O2 with 3 μm-size in diameter exhibited higher initial coulombic efficiency (94.9%), rate capacity (156 mA h g−1 at 900 mA g−1), and low-temperature property (157 mA h g−1 at 180 mA g−1, 0 °C) in comparison with the larger one (12 μm). Most impressively, an ultra-stable capacity of 156 mA h g−1 can be retained at 180 mA g−1 even after 300 cycles at 0 °C. As is known, Li[Ni0.6Co0.2Mn0.2]O2 with 3 μm-size has the best result among the reported Li[Ni0.6Co0.2Mn0.2]O2-based cathode materials. The excellent electrochemical performance of the smaller size cathode results from the advantageous hierarchical nanorods architecture, porous characteristics, and reduced ions/electrons transport path.