Immobilization of Ethynyl-π-Extended Electron Acceptors with Amino-Terminated SAMs by Catalyst-Free Click Reaction

Surface modification of SiO₂ using a catalyst-free quantitative reaction between an amine and an ethynyl-π-extended naphthalenediimide was investigated. A post-reaction method, in which the catalyst-free reaction was performed at the surface after the formation of amino-terminated self-assembled monolayers (SAMs), resulted in dense, uniform modification of the SiO₂ surface with the naphthalenediimide molecules. Both X-ray reflectivity and angle-resolved X-ray photoemission spectroscopy showed consistent results for the layer thickness and density. In contrast, a pre-reaction method, in which an amino-silane and the ethynyl-π-extended naphthalenediimide reacted first and then formed a SAM, afforded a sparse SAM on the SiO₂ surface, probably due to the steric hindrance of the naphthalenediimide moieties. The in situ decoration of the SiO₂ surface by a catalyst-free quantitative reaction offers a facile route for modifying surface properties with various π-conjugated molecules suitable for many applications.

Chitin derived biochar for efficient capacitive deionization performance

The selection and preparation of an electrode material is the core of capacitive deionization. In order to obtain a material with a good deionization properties, we have designed an environmentally-friendly and simple way of preparing biochar. In this work, biochar was prepared by a thermal-deposition method and after chemical modification it was characterized with a scanning electron microscope (SEM), Fourier transform infrared spectrophotometer (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The specific surface area of biochar modified by KOH is as high as 833.76 m² g⁻¹, but the specific surface area of the unmodified electrode material is only 126.43 m² g⁻¹. The electrochemical analysis (CV and EIS) of the biochar indicates that HC-800 has a lower charge transfer resistance and a higher specific capacitance, where the specific capacity of HC-800 reaches 120 F g⁻¹. A CDI property analysis of HC-800 shows a better electrosorption capacity of 11.52 mg g⁻¹ and better regeneration and cycling stability than CS-800. The desalination amount remains 87.23% after several cycles.

Schematic illustration of the fabrication of chitin derived biochar and KOH-activated chitin derived biochar electrodes for capacitive deionization.

Rice Husk-Derived High Surface Area Nanoporous Carbon Materials with Excellent Iodine and Methylene Blue Adsorption Properties

Iodine and methylene blue adsorption properties of the high surface area nanoporous carbon materials derived from agro-waste and rice husk is reported. Rice husk was pre-carbonized at 300 °C in air followed by leaching out the silica nanoparticles by extraction with sodium hydroxide solution. The silica-free rice husk char was mixed with chemical activating agents sodium hydroxide (NaOH), zinc chloride (ZnCl2), and potassium hydroxide (KOH) separately at a mixing ratio of 1:1 (wt%) and carbonized at 900 °C under a constant flow of nitrogen. The prepared carbon materials were characterized by scanning electron microscopy (SEM), Fourier transformed-infrared spectroscopy (FT-IR), powder X-ray diffraction (pXRD), and Raman scattering. Due to the presence of bimodal micro- and mesopore structures, KOH activated samples showed high specific surface area ca. 2342 m2/g and large pore volume ca. 2.94 cm3/g. Oxygenated surface functional groups (hydroxyl, carbonyl, and carboxyl) were commonly observed in all of the samples and were essentially non-crystalline porous particle size of different sizes (<200 μm). Adsorption study revealed that KOH activated samples could be excellent material for the iodine and methylene blue adsorption from aqueous phase. Iodine and methylene blue number were ca. 1726 mg/g and 608 mg/g, respectively. The observed excellent iodine and methylene blue adsorption properties can be attributed to the well-developed micro- and mesopore structure in the carbon material. This study demonstrates that the agricultural waste, rice husk, and derived nanoporous carbon materials would be excellent adsorbent materials in water purifications.

A cellulose acetate/Amygdalus pedunculata shell-derived activated carbon composite monolith for phenol adsorption

Amygdalus pedunculata is expected to be a good candidate plant for desert reclamation (“greening”) since it has notable tolerance to cold and drought and can grow in a wide range of areas with different soil types and moisture contents. In this study, we have developed a single-step method to fabricate a cellulose acetate (CA)/A. pedunculata shell (APS)-derived activated carbon (AC) composite monolith by thermally induced phase separation (TIPS) for removal of toxic phenol from aqueous solution. The composite monolith was easily fabricated by TIPS of a CA solution in the presence of the dispersed AC, in which AC was well loaded onto the monolithic skeleton of CA. The as-obtained monolith showed a maximum adsorption capacity of 45 mg g⁻¹ at the initial phenol concentration of 0.8 mg mL⁻¹. The present composite can be prepared with an arbitrary shape by a facile method from cheap materials, and is more convenient to recycle than powder adsorbents. Therefore, the present CA/APS-derived AC composite monolith has great potential as a promising adsorbent of low cost with convenient separation for toxic phenol-containing wastewater.

In this study, we have developed a single-step method to fabricate a cellulose acetate (CA)/APS-derived activated carbon (AC) composite monolith by thermally induced phase separation (TIPS) for removal of toxic phenol from aqueous solution.

Fabrication of N-doped and shape-controlled porous monolithic carbons from polyacrylonitrile for supercapacitors

N-doped and shape-controlled porous monolithic carbon (PMC) was easily fabricated and displayed excellent electrochemical performance as an electrode for supercapacitors.