The carbon-containing bone hydroxyapatite (CBHA) has been obtained from tuna fish bone in which the carbon derived from the organics inside the bones acts as a dispersant. The XRD and TEM results indicated that the obtained HA is on the nanoscale and the N2 adsorption/desorption isotherm showed that CBHA has mesoporous structure with an enhanced specific surface area (1129.0 m2 g−1). Moreover, CBHA as an adsorbent for removal of Congo red (CR) from aqueous solution exhibited high adsorption capacity (329.0 mg g−1) and the adsorption pattern fitted well with Langmuir model (R2 > 0.96). The adsorption kinetics of CBHA for CR followed the pseudo-second-order model. Thermodynamic parameters, including the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), indicated that the adsorption of CR onto CBHA was feasible, spontaneous, and endothermic at the temperature range of 303–323 K. Thus, CBHA as an efficient and low-cost adsorbent can be applied to the treatment of industrial effluents contaminated with CR.

The authors explore the impact of acid treatments on the N-doped porous carbon obtained from fish scales and its Cr(VI) removal capability. HCl and HNO3 are employed to treat the materials to remove template. The materials were characterized by elemental analysis, N2 adsorption/desorption isotherms, X-ray photoelectron spectroscopy and so on. Compared with the materials treated with HNO3, the materials treated with HCl have the larger specific surface area leading to the much higher adsorption capacity and faster adsorption rate of Cr(VI). To investigate the adsorption mechanism, the materials after adsorption of Cr(VI) were measured by X-ray photoelectron spectroscopy. It is found that the adsorbed Cr(VI) is partly reduced to Cr(III). The as-produced Cr(III) is in proportion to the content of quaternary-N in the carbons, which demonstrates the redox reaction between the N-doped porous carbon and Cr(VI). Remarkably, the materials carbonized at 800 °C treated with HCl reach equilibrium in 100 min and achieve the maximum capacity up to 416.67 mg g−1.

Nitrogen and oxygen co-doped hierarchical porous carbon (N,O-HPC) networks has been synthesized using cattle bones as precursors via pre-carbonization and carbonization combined with KOH activation. The effects of carbonization and activation temperature on the physiochemical and electrochemical performances of the N, O-HPCs were systematically studied. The N,O-HPC obtained at 850 °C (referred to as N,O-HPC-850) possesses a mesopore-dominant hierarchical porous network with a large specific surface area (2520 m2 g−1), a relatively high content of N (1.56%) and O (10.2%) and a good electrical conductivity (421.9 S m−1). As it is used as supercapacitor electrode material, N,O-HPC-850 exhibits a large specific capacity (444 F g−1 at a scan rate of 5 mV s−1 and 435 F g−1 at a current density of 0.1 A g−1, respectively) and good rate performance (252 F g−1 at a scan rate of 500 mV s−1 and 309 F g−1 at a current density of 20 A g−1, respectively) in 6 M KOH solution. Moreover, the assembled symmetric supercapacitor based on N,O-HPC-850 electrode delivers the energy density of 30.3 and 9.7 Wh kg−1 at the power density of 0.341 and 43.8 kW kg−1, respectively, and exhibits a good cycling stability with a capacitance retention of 97.5% after 20000 cycles in 1 M Na2SO4 solution.In-situ nitrogen and oxygen co-doped carbon networks with a mesopore-dominant hierarchical porosity were prepared from cattle bone and exhibited superior performance as electrode material for high energy and power density supercapacitor.Download high-res image (253KB)Download full-size image

•micropores of FBPC confine the dissolved polysulfides and offer adequate electrochemical reaction interface;•mesopores in FBPC facilitate infiltration of the electrolyte and accommodate the volume expansion/contraction during the discharge/charge process;•the doped N/S/O heteroatoms present strong polysulfides binding, increase the reactive sites and enhance the electroconductivity of carbon;•Li-S batteries with FBPC modified separator achieved ultralong life span and excellent electrochemical performance.Nowadays, the practical application of Li-S batteries is still inhibited by its inferior cycle stability caused by the shuttle effect. Herein, we report the design and fabricate of a fishbone based porous carbon (FBPC) for ultralong cycle life Li-S batteries. Prepared by carbonizing the tuna bone with activation process, FBPC is a heteroatoms-doped hierarchical porous carbon material which owns following merits: i) micropores of FBPC confine the dissolved polysulfides and offer adequate electrochemical reaction interface; ii) mesopores of FBPC not only facilitate infiltration of the electrolyte but also accommodates the volume expansion/contraction during the discharge/charge process; iii) the doped N/S/O heteroatoms increase the reactive sites, present strong polysulfides binding and improve the electroconductivity of carbon matrix. Li-S batteries with FBPC separator exhibit excellent cycling stability (0.064% capacity fading per cycle at 1C) and deliver a high discharge capacity of 1397.5 mAh g−1 at 0.2C. Even after 700 cycles the capacity still retain as high as 599.9 mAh g−1 at 1C. These superior performances as well as abundant precursor and facile preparation process represent the promising prospect of the designed FBPC being applied to the high-performance Li-S batteries.Carbonizing the tuna bone to acquire heteroatoms-doped porous carbon materials, and coating this as-prepared material on the PP separator for ultralong cycle life Li-S batteries.Download high-res image (371KB)Download full-size image

Lithium–sulfur (Li–S) batteries with high energy density are considered as promising for rechargeable energy storage. However, the shuttle effect hinders their practical application. Here, novel nitrogen-doped micro-/mesoporous carbon (N-MIMEC), derived from crab shells, was fabricated via a sustainable and cost-effective route. A modified separator coated with an N-MIMEC layer for Li–S batteries exhibits many advantages: (1) the micro-/mesopores provide enough surface area for sulfide adsorption, and accommodate the volume change; (2) the nitrogen in N-MIMEC enhances polysulfide adsorption and increases the electronic conductivity of the carbon framework; and (3) the conductive layer acts as an upper current collector, increasing the electrical conductivity. An enhanced Li–S battery with an N-MIMEC-coated separator was constructed, with an initial capacity of 1301 mA h g−1 and a high reversible capacity of 971.3 mA h g−1 after 100 cycles at 0.1C. Also, upon further increasing the sulfur loading from 63 wt% to 77 wt%, the corresponding Li–S batteries exhibit a high reversible capacity of 578 mA h g−1 after 500 cycles at 1C, with a decay rate of about 0.029% per cycle. Considering the green and sustainable source material, simple preparation and good electrochemical performance, the N-MIMEC-coated separator is promising for Li–S battery applications.

•Nano-HA has been demonstrated as an efficient polysulfide absorbent.•The shuttle effect of polysulfide in Li-S battery has been confined by the nano-HA.•Nano-HA used as additive improved electrochemical performance of Li-S battery.Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates for developing advanced energy storage system, but the polysulfide shuttle effect remains the biggest obstacle for its practical application. In this work, nano-hydroxyapatite (Ca5(PO4)3(OH)) was used as an additive in the sulfur cathode and carbon-coated separator to prevent the polysulfide shuttle effect and thus to achieve the high performance. The sulfur cathode with nano-hydroxyapatite exhibited a higher reversible capacity and a more stable cycling performance than that of the pristine sulfur cathode. The improved capacity retention from 58% (100th) to 73% (200th) after introducing nano-hydroxyapatite into the sulfur cathode confirmed its strong polysulfide absorption ability. Furthermore, a nano-hydroxyapatite modified separator was developed to suppress the polysulfide shuttle effect and to facilitate the reutilization of sulfur species. The nano-hydroxyapatite particles served as polysulfide absorbents to bind polysulfides and suppress their diffusion to the anode. The batteries assembled with this separator exhibited a high reversible capacity of 886 mAhg−1 at 0.1C and 718 mAh g−1 at 0.5C after 200 cycles, with a low capacity fading of ∼0.10-0.11% per-cycle. At the highest sulfur loading of 4.5 mg cm−2 used for practical applications, the reversible areal capacity was much higher than the areal capacity (4 mAh cm−2) of commercial lithium-ion batteries. Therefore, the strategy using nano-hydroxyapatite as polysulfide absorbent shows great potential for solving the polysulfide shuttle problem and developing high performance Li-S batteries.

Chitosan with abundant hydroxyl and amine groups as an additive for cathodes and separators has been proven to be an effective polysulfide trapping agent in lithium–sulfur batteries. Compared with common sulfur cathodes, the cathode with chitosan shows an enhanced initial discharge capacity from 950 to 1145 mA h g−1 at C/10. The reversible specific capacity after 100 cycles increases from 508 mA h g−1 to 680 mA h g−1 and 473 to 646 mA h g−1 at rates of C/2 and 1 C, respectively. In addition, batteries with separators that are coated with a carbon/chitosan layer can exhibit a high discharge capacity of 830 mA h g−1 at C/2 after 100 cycles and 675 mA h g−1 at 1 C after 200 cycles with the capacity fading to as low as 0.11% per cycle. This study demonstrates the benefits of using chitosan for not only lithium–sulfur batteries but also potentially other sulfur-based battery applications.

This article reports a strategy to use fish scales as raw materials for synthesizing CO2 capture materials. The synthesis employs thermal and chemical treatment to convert fish scales into N-rich porous carbons. The proteins in the fish scales are the major source of carbon and nitrogen. By varying the reaction conditions, the porosity and N content can be controlled in the produced porous carbons. It was found that the porosity first increases and then decreases with an increase in thermal treatment temperature; the N content decreases with an increase in the temperature. The capture capacity of the as-synthesized carbon (NFPC-750) for CO2 can be up to 171 mg g−1 at 25 °C, 1 bar. This high capacity is attributable to its porous structure with a high specific surface area (up to 3206 m2 g−1) and large pore volume (micropore volume up to 0.76 cm3 g−1 and total pore volume up to 2.29 cm3 g−1). More attractively, quaternary nitrogen is effectively preserved (2.90% N), which should be another contributor to enhance the CO2 capture capacity through the chemical adsorption between nitrogen groups and CO2. In addition, the sorbent preliminarily exhibits high cycle stability with retention of 91.8% of its initial CO2 capacity after 10 cycles. This highly porous N-doped porous carbon obtained from fish scales is thus considered a promising material for CO2 capture.

Acylated gelatine has been successfully used in the sulphur cathode for a Li/S battery. The results indicated that acylated gelatine could effectively constrain the resolution of polysulphide into the electrolyte because of carbonyl groups' strong affinity for polysulphide. Meanwhile it also served as a strong dispersion and adhesion agent for the cathode materials. Cyclic voltammograms and electrochemical impedance spectroscopy experiments showed that the prepared cathodes have less polarization and lower transfer resistance compared to gelatine binder-sulphur cathode. The prepared cathode exhibited a much higher initial and reversible capacity after 100 cycles at rates of 0.1 and 0.5 C than that of gelatine binder-sulphur cathode under the same condition. Our findings have shown that acylated gelatine is a promising binder to improve Li–S performance and helpful for its future development.

The adsorption of methylene blue (MB) from aquatic systems by the fish-scale-based hierarchical lamellar porous carbon (FHLC) was investigated. In this paper, the FHLC was used as an alternative adsorbent to replace the Norit CGP, a commercial activated carbon, and showed an overall fast and pH-dependent MB adsorption. The effect of contact time, pH and concentration on MB adsorption was investigated. It was found that the adsorption behaviours of FHLC and CGP could be described by a monolayer Langmuir type isotherm. The kinetic data followed the pseudo second-order kinetic model for both activated carbons as the linear correlation coefficients were all above 0.9999. Thermodynamic analyses indicated that the adsorption was an endothermic and spontaneous physisorption process. The maximum Langmuir adsorption capacity of the FHLC was 555.55 mg g−1 at pH = 7.07 and 1050.72 mg g−1 at pH = 11.00 while that of the CGP was 432.90 mg g−1 at pH = 7.07 and 649.35 mg g−1 at pH = 11.00, respectively. The adsorption capacity of the FHLC was much better than that of the CGP at different pH values. Our study shows that fish-scale-based carbon could be used as a high-performance and cost-effective adsorbent to remove MB in aqueous solution in the wastewater treatment.

•Gelatin-based sol-gel method was employed to synthesis the nanosized LiFePO4/C.•The as-synthesized product exhibited a high tap density of 1.42 g cm−3.•The nanocomposite cathode shows good cycling with capacity retention of 95.2%.•The discharge capacity of the cathode can reach 128 mAh g−1 at 5 C.An additive-free gelatin-based sol–gel procedure was developed to synthesize the nanosized LiFePO4/C powders for lithium ion batteries. The as-synthesized product exhibits a narrow particle size distribution (100–300 nm), and it has a tap density of 1.42 g cm− 3. It is found that the LiFePO4/C nanocomposite cathode shows excellent cycle ability with capacity retention of 95.2% at 0.2 C after 100 cycles. Moreover, the battery has achieved an improved rate performance, and the discharge capacity of the cathode can reach 128 mAh g− 1 at 5 C.

Chitosan with abundant hydroxyl and amine groups as an additive for cathodes and separators has been proven to be an effective polysulfide trapping agent in lithium–sulfur batteries. Compared with common sulfur cathodes, the cathode with chitosan shows an enhanced initial discharge capacity from 950 to 1145 mA h g−1 at C/10. The reversible specific capacity after 100 cycles increases from 508 mA h g−1 to 680 mA h g−1 and 473 to 646 mA h g−1 at rates of C/2 and 1 C, respectively. In addition, batteries with separators that are coated with a carbon/chitosan layer can exhibit a high discharge capacity of 830 mA h g−1 at C/2 after 100 cycles and 675 mA h g−1 at 1 C after 200 cycles with the capacity fading to as low as 0.11% per cycle. This study demonstrates the benefits of using chitosan for not only lithium–sulfur batteries but also potentially other sulfur-based battery applications.