Sodium lignosulfonate/graphene composites for efficient desalination by incorporating CoS to control pore size.

The phenomenon of overlapping double layers due to micropores inhibits capacitive deionization performance, which is improved by increasing the pore size. In this study, a novel ternary composite electrode (sodium lignosulfonate/reduced graphene oxide/cobalt sulfide, LGC) was designed using a two-step hydrothermal method. CoS with high pseudocapacitance modifies sodium lignosulfonate and graphene connected by hydrogen bonding, benefiting from the constitutive steric structure. The electrochemical performance was significantly enhanced, and the desalination capacity substantially improved. The LGC electrode specific capacitance was as high as 354.47 F g-1 at a 1 A g-1 current density. The desalination capacity of the capacitive deionization device comprising LGC and activated carbon in 1 M NaCl electrolyte reached 28.04 mg g-1 at an operating condition of 1.2 V, 7 mL min-1. Additionally, the LGC electrodes degraded naturally post the experiment by simply removing the CoS, suggesting that the LGC composites are promising material for capacitive deionization electrodes.

Rapid fabrication of tough sodium alginate/MXene/poly(vinyl alcohol) dual-network hydrogel electrolytes for flexible all-solid-state supercapacitors.

With the rapid development of flexible portable devices, polymer-based hydrogel electrolytes have drawn tremendous attention and widespread interest to replace conventional liquid electrolytes. Herein, an eco-friendly, low cost and fast method was adopted to synthesize novel cross-linked dual-network hydrogel electrolytes (PVA/SA/MXene-NaCl) within 5 min due to the formation of borate bonds. The unique dual-network structure of hydrogel enabled hydrogel electrolytes to efficiently dissipate energy under deformation and the formation of borate bonds endowed hydrogel with self-healing ability. Benefited from the introduction of NaCl and MXene, the hydrogels displayed a high ionic conductivity (40.8 mS/cm) and enhanced mechanical strength (650 kPa). Notedly, the flexible supercapacitor with low concentration of NaCl (0.3 mol L-1) delivered a superior areal capacitance of 130.8 mF cm-2 at 1 mA cm-2 and 106.2 mF cm-2 at 3 mA cm-2, and simultaneously offered remarkable capacitance retention under the state of bending, self-healing (five cycles), compression and stretching. Moreover, as-assembled supercapacitor maintained about 88.9 % of its original capacitance and 90.5 % of Coulombic efficiency after 5000 charge-discharge cycles. Our research presented a simple and universally pathway to prepare flexible energy storage devices with excellent mechanical and electrochemical properties.

Biomass-derived carbon dots regulating nickel cobalt layered double hydroxide from 2D nanosheets to 3D flower-like spheres as electrodes for enhanced asymmetric supercapacitors.

Layered double hydroxides (LDHs) often require the use of carbon materials to improve their stability, conductivity, and specific surface area to accommodate new directions in the development of high-performance energy storage materials. Herein, 2D nickel cobalt layered double hydroxide (NCLDH) nanosheets are regulated to form 3D flower-like spheres by fungus bran-derived carbon dots (CDs) via an in situ growth method. The prepared sample (CDs/NCLDH) shows abundant accessible active sites and favorable electrical conductivity, which is aided by strong interactions between CDs and NCLDH. The optimized CDs/NCLDH exhibits significantly enhanced electrochemical performances, including ultrahigh specific capacitance (2100F g-1 at 1 A g-1) and a great rate capability, which are two times higher than those of the NCLDH electrode. Additionally, the asymmetric supercapacitor device assembled with the CDs/NCLDH positive electrode and the fungus bran-derived activated carbon (FBC) negative electrode achieves a superior energy density of 52.5 Wh kg-1 at an ultrahigh powder density of 750 W kg-1. With their simple synthesis method and excellent electrochemical performance, the role of the CDs provides new insights for the development of LDHs with improved performance.

Research Progress in the Field of Adsorption and Catalytic Degradation of Sewage by Hydrotalcite-Derived Materials.

With the rapid development of industry and agriculture and the greatly improved living conditions, the resultant gradually deteriorated environments threaten the human beings. Refractory or even toxic pollutants, which are from different industries such as printing and dyeing, pesticides, chemicals, petrochemicals, plastics and rubber, seriously threat the ecosystems and human health. Having the advantages of flexible composition, unique structure, high stability, memory effect, easy preparation and low cost, hydrotalcite compounds have a great potential in sewage degradation and environmental protection. This study focuses on the adsorption and catalytic properties (such as photocatalysis, electrocatalysis and photoelectrocatalysis) of hydrotalcite-derived materials for treating organic, inorganic and heavy metal ion sewage. The types of adsorption and catalysis, and the effects of various influencing factors on the degradation efficiency were discussed as well.

Microwave solvothermal carboxymethyl chitosan templated synthesis of TiO2/ZrO2 composites toward enhanced photocatalytic degradation of Rhodamine B.

A series of TiO2/ZrO2 composites with various molar ratios of ZrO2:TiO2 were synthesized by a facile and mild microwave hydrothermal method with carboxymethyl chitosan (CMCS) as templates. The as-obtained products were characterized with wide-angle powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectrophotometry (UV-vis-DRS), N2 adsorption-desorption isotherms (BET), and X-ray photoelectron spectrometer (XPS). The TiO2/ZrO2 composites with heterogeneous structure consisted of particles which showed a better regularity and uniform with about 800 nm in diameter, and showed a larger specific surface area and smaller energy band gap than pure ZrO2. Comparative experiments including varying the pH of the solution and the content of titania demonstrated that the 5% TiO2/ZrO2 composites (nTi:nZr = 5:100) at pH = 10.3 possessed the best photocatalytic property. Moreover, the possible reasons for these phenomena were clarified. Cyclic experiments proved that the resulting TiO2/ZrO2 composites as photocatalyst could be reused efficiently. Meanwhile, a possible mechanism of photocatalysis was proposed.