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In this study, we reported a facile two-step reduction method to prepare a high-quality graphene with intact structure. Hydroxyl group is acquired by utilizing LiAlH4 to reduce the oxygen-containing functional groups in GO. Then it is further reduced by ethanethiol/aluminum trichloride (Et-SH/AlCl3) to obtain graphene. The results of Infrared and XPS showed that the prepared graphene material (rGO2) has been reduced completely and had structural integrity. Besides, the conductivity of rGO2 obtained can reach 2.632 * 103 S m−1, which is higher than that obtained by general chemical reduction method and high temperature reduction method. Investigated as a potential material for supercapacitors, the as-prepared graphene reveals excellent electrochemical properties, including good rate capability and cycling stability, which mainly benefits from its intact structural characteristics.

In this study, the crystalline and homogenous ZnTiO3 particles were first synthesized in KCl-NaCl eutectic chloride salts at 700–850 °C. Then the ZnTiO3 was successfully loaded onto g-C3N4 sheets to form ZnTiO3/g-C3N4 composites during the polymerization of melamine. Compared with pure g-C3N4, ZnTiO3/g-C3N4 composites have shown an obvious red shift phenomenon and enhanced light harvesting ability in the spectra range of 200–800 nm as well as much lower recombination rate of the photogenerated charge carriers. The ZTOCN1-800 samples exhibited a 1.69 times specific surface area as pure g-C3N4 by BET analysis, and a 76% degradation efficiency for methyl orange (MO) under visible light irradiation in 180 min, about 13 times as that of pure ZnTiO3 and 3 times as that of pure g-C3N4. Moreover, The ZTOCN1-800 samples achieved complete degradation of MB and RhB under visible light irradiation within 90 min. This is attributed to the intimate heterostructure interface between g-C3N4 and ZnTiO3 due to ZnTiO3 particles intercalation into the g-C3N4 sheets, which reduced the self-aggregation of the g-C3N4 sheets and greatly facilitated the charge transfer from photo-excited g-C3N4 to ZnTiO3. These were demonstrated by XRD, SEM, EDX, TEM, UV–Vis, PL and photoelectrochemical analysis.

In this work, zero-dimensional (0D)/ two-dimensional (2D) TiO2/g-C3N4 composite photocatalysts with homogeneous well-developed heterostructures were successfully prepared from LiCl-KCl flux using a facile molten salt assisted in-situ route. The phase composition, morphology, surface area, chemical structure, thermal stability as well as optical property of the heterostructured composites were systematically characterized. Benefiting from the exfoliation effect of molten salt flux, the flux-grown g-C3N4 products exhibit a rough surface with porous structures and many co-existed secondary products including nanosheets, nanrods and nanotubes, which also lead to an obvious increase in the surface area of the flux-grown g-C3N4 and composites. The photocatalytic performance of the TiO2/g-C3N4 heterostructure composites was evaluated by photodegradation of methyl orange (MO) and rhodamine B (RhB) under the visible light irradiation (λ > 420 nm), and proved to be greatly improved compared to individual TiO2 and g-C3N4. Moreover, the enhanced photocatalytic activity of TiO2/g-C3N4 composites can be attributed to the higher surface area and the synergistic effects between TiO2 and g-C3N4 including the increased light harvesting ability and more efficient separation of the photogenerated charge carriers, which originates from the construction of TiO2/g-C3N4 heterostructures at the interface between the two components. Furthermore, a possible mechanism responsible for the enhanced photocatalytic performance was also proposed. Additionally, the TiO2/g-C3N4 composites showed a superior adsorption ability for the removal of cationic dye methylene blue (MB) from aqueous solutions, due to their high surface area and strong electrostatic interactions between catalysts and dye molecules.

Three-dimensional sponge-like reduced graphene oxide/silicon/carbon nanotube composites were synthesized by one-step hydrothermal self-assembly using silicon nanoparticles, graphene oxide and amino modified carbon nanotubes to develop high-performance anode materials of lithium ion batteries. Scanning electron microscopy and transmission electron microscopy images show the structure of composites that Silicon nanoparticles are coated with reduced graphene oxide while amino modified carbon nanotubes wrap around the reduced graphene oxide in the composites. When applied to lithium ion battery, these composites exhibit high initial specific capacity of 2552 mA h/g at a current density of 0.05 A/g. In addition, reduced graphene oxide/silicon/carbon nanotube composites also have better cycle stability than bare Silicon nanoparticles electrode with the specific capacity of 1215 mA h/g after 100 cycles. The three-dimension sponge-like structure not only ensures the electrical conductivity but also buffers the huge volume change, which has broad potential application in the field of battery.

We proposed a large-sized graphene preparation method by short-circuit discharge of the lithium-graphite primary battery for the first time. LiCx is obtained through lithium ions intercalation into graphite cathode in the above primary battery. Graphene was acquired by chemical reaction between LiCx and stripper agents with dispersion under sonication conditions. The gained graphene is characterized by Raman spectrum, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Atomic force microscope (AFM) and Scanning electron microscopy (SEM). The results indicate that the as-prepared graphene has a large size and few defects, and it is monolayer or less than three layers. The quality of graphene is significant improved compared to the reported electrochemical methods. The yield of graphene can reach 8.76% when the ratio of the H2O and NMP is 3:7. This method provides a potential solution for the recycling of waste lithium ion batteries.

In this work, boron and nitrogen co-doped hierarchical porous carbon (BN-HPC) with a relatively high contents of boron (3.97 wt%) and nitrogen (12.10 wt%) is synthesized by a method combined with template process and carbonization of hierarchical porous resin using melamine and boric acid as nitrogen and boron sources, respectively. The co-doping method achieves a high boron doping level (8 times of that of single boron doped sample) which is of great significance in increasing the doping efficiency of boron. The hierarchical porosity, structure and surface chemical properties are studied in detail via various means, such as Transmission Electron Microscopy, N 2 sorption, X-ray diffraction, X-ray photoelectron spectroscopy and elemental analysis, etc. Owing to the synergistic effect of hierarchical porosity and heteroatoms doping, BN-HPC exhibits greatly improved electrochemical capacitive performance of 304 F g −1 at a current density of 0.1 A g −1 and good rate capability (189 F g −1 remained at a current density of 10 A g −1 ). The strategy of synthesis is facile and very effective.

Two-dimensional (2D) graphitic-C3N4 (g-C3N4) was successfully hybridized with one-dimensional (1D) flux-grown Na-modified K2Ti6O13 nanobelts (Na-K2Ti6O13 NBs) for the first time to construct novel 1D/2D Na-K2Ti6O13/g-C3N4 heterostructured photocatalysts using a facile mixing–calcination method. The heterostructured Na-K2Ti6O13/g-C3N4 composites with three-dimensional (3D) hybrid architectures exhibited a remarkably enhanced photocatalytic efficiency for organic pollutant degradation in comparison with pure Na-K2Ti6O13 and g-C3N4 under both simulated sunlight and visible-light irradiation (λ > 420 nm), which could be mainly attributed to the synergistic effects between Na-K2Ti6O13 and g-C3N4 including more efficient interfacial charge transfer, longer lifetimes and the stronger oxidation and reduction ability of photogenerated charge carriers, fundamentally originating from the formation of Na-K2Ti6O13/g-C3N4 heterojunctions based on the well-matched energy-band structures. Moreover, the Na-K2Ti6O13/g-C3N4 hybrids showed good stability and reusability for the photocatalytic degradation of organic pollutants. Finally, the possible mechanisms responsible for the improved simulated sunlight and visible-light photocatalytic performance were also investigated, respectively, based on the results of PL spectra, time-resolved fluorescence decay spectra, radical species trapping experiments, ESR spectra and PL-TA measurements. Overall, this work will not only be beneficial for the design and development of more efficient visible-light-responsive g-C3N4-based composites for solar energy conversion and environmental remediation but will also be influential in optimizing the visible-light photocatalytic activity of wide-band-gap 1D titanate nanomaterials to meet the requirements of practical applications.

Microspherical polyaniline/graphene (PANI/G-MS) composites are synthesized using sheet-like polyaniline/graphene oxide (PANI/GO) composites as raw materials via spray-drying and chemical reduction process, in which the granulated polyaniline (PANI) is in-situ grown on the surface of graphene oxide. For PANI/G-MS composites, PANI uniformly coats on the surface of graphene which can constitute a high conductive network to accelerate electronic transmission in the composites electrode for supercapacitors. Moreover, PANI/G-MS composites form numerous channels among their spherical particles during random stacking of sheet-like PANI/GO composites via spray-drying process. Due to the special structure, the electrochemical capacitance of the as-synthesized PANI/G-MS composite reaches 596.2 and 447.5 F g −1 at a current density of 0.5 and 20 A g −1 , respectively, indicating superior rate capability. Additionally, after 1500 cycles at a current density of 2 A g −1 , 83.7% of the initial capacitance is retained.

In this paper, nitrogen/phosphorous co-doped porous carbons (N/P-PCs) with hierarchical porosity were prepared by a one-step carbonization method, of which nitrogen-containing PAA/MMF is the precursor and phosphorous-containing sodium hypophosphite monohydrate is the novel pore-forming agent. The synergistic effect of multilevel porosity and heteroatomic functionalities results in good electrochemical performance. Tested as electrode materials for supercapacitors, N/P-PC-50 demonstrates a maximal specific capacitance of 177 F g−1 at a current density of 0.1 A g−1, excellent rate capability (67% capacitance retention at 10 A g−1) and superior cycling stability (no capacitance loss after 10000 cycles). In addition, N/P-PCs have the potential to be used for other applications, and this facile, low-cost and safe synthesis strategy provides a feasible route to develop many hierarchically porous carbon-based materials.

A series of nitrogen doped porous carbons are prepared using a simple and economic template carbonization method, in which nano-CaCO3 and ethylenediamine (EDA) and carbon tetrachloride (CTC) serve as a template and nitrogen-containing carbon precursors, respectively. The textural parameters of all the obtained carbon materials are tunable. The porosity and nitrogen content of the nitrogen doped porous carbons strongly depend on the dosage of nano-CaCO3. When the ratio of CaCO3 to the sum weight of EDA and CTC increases from 0.2 to 0.4, the specific surface area increases from 783.72 to 2535.09 m2 g−1, meanwhile the nitrogen content decreases from 16.13 to 9.47 wt%. While when the ratio of CaCO3 to the sum weight of EDA and CTC is moderate, the as-prepared nitrogen doped porous carbons (NPC-0.3) contains as high as 13.45 wt% of nitrogen has a balanced specific surface areas of 1276.14 m2 g−1, exhibits the largest specific capacitance of 226 F g−1 at a current density of 0.1 A g−1 in 1 M H2SO4 aqueous electrolyte, due to the co-contribution of double layer capacitance and pseudo-capacitance. Additionally, it shows excellent rate capability (capacitance retention ratio of 58.4% at a current density of 30 A g−1) and good cycling stability (no capacitance decay over 10 000 charge-discharge cycles), making it a promising electrode material for supercapacitors.

In this work, composite membranes consisting of triethylmethylammonium bis(fluorosulfonyl)imide (N1222FSI), poly(ethylene oxide) (PEO) and lithium bis(fluorosulfonyl) imide (LiFSI) have been produced as solid polymer electrolytes (SPEs). The composite SPEs provide good mechanical property, high ionic conductivity at 50 °C, high electrochemical and thermal stability as well as superior interfacial compatibility with lithium metal. Moreover, Li/LiFePO4 cells containing the best-performing SPE exhibit high discharge capacity and excellent cycling performance. The results show that the novel composite SPEs might be promising electrolytes applied in all-solid-state lithium batteries.

Nitrogen-doped porous carbon materials (NPCs) were successfully obtained through one-step carbonization of an ionic liquid, that is, 1-ethyl-3-methylimidazolium dicyanamide (EMIM-dca), adopting eutectic salt (ZnCl2-NaCl) as the porogen agent. The nitrogen content and textural structure of the obtained carbon materials are highly dependent on the dosage of salt. The as-prepared NPCs integrate the superiorities of reasonable pore structure, high nitrogen content as well as homogeneous distribution, and high surface area. When served as electrodes for supercapacitor, a typical NPC-2 electrode exhibits a high specific capacitance of 335.3 and 206 F g−1 at current densities of 0.5 and 10 A g−1, respectively, considerable energy density (up to 10.1 Wh kg−1), and excellent cycling stability with almost no degradation over 10,000 cycles in KOH aqueous solution.

Organic materials have been promising materials for “greener and sustainable” lithium-ion batteries due to lightweight, low cost, flexibility, alternative molecular engineering. Six kinds of aromatic imides with different aromatic and aliphatic diamines based on 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) were designed, synthesized and studied as anode materials in rechargeable lithium-ion batteries in this work. Compared with ortho-substituted and meta-substituted phenylenediamine, aromatic imide synthesized by p-phenylenediamine shows excellent electrochemical performance on account of its well-organized structure, which possesses 558 mA h g−1 of discharge capacity after 50 cycles at the current density of 25 mA g−1. Besides, imides with shorter alkyl chain would help improve the proportion of electrochemical active conjugated carbonyl compounds, leading to higher capacity. Thus, imide-based electrode materials can be designed efficiently by symmetrical and straight chain structure and less inactive part to gain optimum molecular structure, making it a promising alternative anode material for rechargeable lithium-ion batteries.

A novel anode material for lithium-ion batteries derived from aromatic imides with multicarbonyl group conjugated with aromatic core structure is reported, benzophenolne-3,3',4,4'-tetracarboxylimide oligomer (BTO). It could deliver a reversible capacity of 829 mA h g-1 at 42 mA g-1 for 50 cycles with a stable discharge plateaus ranging from 0.05-0.19 V versus Li+ /Li. At higher rates of 420 and 840 mA g-1 , it can still exhibit excellent cycling stability with a capacity retention of 88% and 72% after 1000 cycles, delivering capacity of 559 and 224 mA h g-1 . In addition, a rational prediction of the maximum amount of lithium intercalation is proposed and explored its possible lithium storage mechanism.