Enhanced full-seawater splitting with a CoNiP@N,P-C core-shell electrocatalyst.

This study investigated a novel electrocatalyst with a core-shell structure of CoNiP@N,P-C. The unique carbon shell of this catalyst serves a dual purpose: exposing numerous active sites and safeguarding CoNiP nanoparticles from dissolution caused by the electrolyte. As a result, the CoNiP@N,P-C nanoparticles exhibit exceptional electrochemical properties. The CoNiP@N,P-C catalyst displays overpotentials of 234 and 314 mV for the HER and OER, respectively, within a simulated seawater solution (1 M KOH + 0.5 M NaCl), indicating its outstanding catalytic performance. Moreover, when subjected to full seawater splitting, the CoNiP@N,P-C catalyst exhibited high activity, achieving a 1.71 V cell voltage at a current density of 10 mA cm-2. As revealed by density functional theory (DFT) calculations, the CoNiP@N,P-C catalyst exhibits Gibbs free energy for hydrogen adsorption (ΔGH* = -0.19 eV) that is decreased in comparison with CoP@N,P-C, NiP@N,P-C, and N,P-C (-0.321 eV, -0.434 eV, and 0.723 eV, respectively). This finding confirms that the core-shell structure plays a role in enhancing the HER kinetics and improving the catalytic performance, which is consistent with the experimental observations. Consequently, this study introduces the concept of utilizing bimetal phosphide core-shell structures for overall seawater splitting, offering a novel approach in this field of research.

Preparation and pore-forming mechanism of hydrogen bond and ionic bond double-driven chitosan-based mesoporous carbon.

Using chitosan as the carbon source, F127 as the template, and sodium tripolyphosphate as cross-linking agent, a hydrogen bond and ionic bond double-driven mesoporous carbon material was prepared via the sol-hydrothermal method and its formation mechanism was discussed. According to the results from FTIR, Raman, XPS, physical adsorption analyzer, SEM, TEM, and TG-IR, the mesoporous carbon material was formed under the synergistic effect of hydrogen bond and ionic bond has a mesoporous volume of 0.44 cm3/g, a BET surface area of 262 m2/g, and possesses the ideal unimodal distribution around 2.20 nm. The mesopores are originated from the degradation of hydrophobic segment PPO of F127, and the micropores come from the gases CO2, CO, NH3, CH4, tetraethylene glycol dimethyl ether, and 2,6-diisopropylphenyl isocyanate produced during the degradation of prepolymers. The maximum adsorption capacity of this mesoporous carbon for tannic acid (Sips model) at 30 °C is 70.4 mg/g.

Oxidation modification of chitosan-based mesoporous carbon by soft template method and the adsorption and release properties of hydroxycamptothecin.

Spray drying and a direct carbonization technology were coupled to prepare nitrogen-doped mesoporous carbon nanoparticles (NMCs) using chitosan as a carbon source and nitrogen source precursor and a triblock amphiphilic copolymer (F127) as a soft template, then oxidative modification was performed by ammonium persulfate (APS) to prepare oxidized mesoporous carbon nanoparticles (O-NMCs). The pore structure, chemical composition and wettability of the mesoporous materials were studied before and after oxidative modification, the microscopic morphology, structure, composition and wetting performance of the mesoporous carbon were characterized by transmission electron microscopy (TEM), an X-ray diffractometer (XRD), N2 adsorption-desorption instrument, X-ray photoelectron spectroscopy (XPS), contact angle tests and other analyses, meanwhile influences of the mesoporous carbon material on adsorption and release performance of a poorly-soluble antitumor drug hydroxycamptothecin (HCPT) were investigated. It was demonstrated from results that the surface wettability of the oxidatively-modified mesoporous carbon material was improved, the contact angle of the mesoporous carbon materials was reduced from 133.4° to 58.2° and the saturated adsorption capacity of HCPT was 676.97 mg/g and 647.20 mg/g respectively. The dissolution rate of the raw material hydroxycamptothecin was improved due to the nanopore structure of the mesoporous carbon material, the dissolution rate of mesoporous carbon material-loaded hydroxycamptothecin was increased from 22.7% to respective 83.40% and 81.11%.

Study on the preparation and mechanism of chitosan-based nano-mesoporous carbons by hydrothermal method.

In this paper, the hydrothermal method to synthesize and characterize nano-mesoporous carbons and their synthesis mechanism are reported. Using tri-block Pluronic F127 as a structuring agent and chitosan (CS) as a carbon source, the nano-mesoporous carbons were synthesized by a one-step sol polymerization and hydrothermal process, followed by carbonization at high temperature. The pore structure of the carbon materials was characterized by physical adsorption analyzer, and the morphology was characterized by SEM and TEM. Fourier-transform infrared, Raman and x-ray photoelectron spectroscopy were used to study the synthesis mechanism. The results showed that the self-assembly polymerization reaction between CS and F127 in a weakly acidic system was only implemented driven by the hydrogen bond auxiliary electrostatic interactions initiated by protonated amino groups. The nitrogen from amino groups and acetylamino groups, the oxygen in acetylamino groups, hydroxyl groups and the glycosidic bonds of CS, and the oxygen from the hydrophilic segments of F127 were the main active sites. The mesoporous material possesses a high Brunauer-Emmett-Teller surface area (163 m2/g) and large pore volume (0.462 cm3/g) with pore diameter around 2.1 nm. The nitrogen content was 1.08% and existed in the pore wall as the form of pyridine, pyrrole and quaternary nitrogen.

One-Step Synthesis of Nitrogen-Doped Hydrophilic Mesoporous Carbons from Chitosan-Based Triconstituent System for Drug Release.

In situ nitrogen-doped hydrophilic mesoporous carbon spheres with different carbon-to-silicon (C/Si) ratios (NMCs-x/3, x = 5, 6, 7, and 8) were prepared by one-step method coupled with a spray drying and carbonizing technique, in which triblock copolymer (F127) and tetraethyl orthosilicate (TEOS) were used as template agents, and biocompatible chitosan (CS) was used as the carbon source and nitrogen source. These carbon materials were characterized by TG, BET, XRD, Raman, FTIR, TEM, XPS, and contact angle measuring device. The adsorption and release properties of mesoporous carbon materials for the poorly soluble antitumor drug hydroxycamptothecin (HCPT) were investigated. Results showed that nanospherical mesoporous carbon materials were successfully prepared with high specific surface area (2061.6 m2/g), narrowly pore size distribution (2.01-3.65 nm), and high nitrogen content (4.75-6.04%). Those NMCs-x showed a satisfactory hydrophilicity, which gradually increased with the increasing of surface N content. And the better hydrophilicity of NMCs-x was, the larger adsorption capacity for HCPT. The absorption capacity of NMCs-x towards HCPT was in the following orders: qNMCs-5/3 > qNMCs-6/3 > qNMCs-7/3 > qNMCs-8/3. NMCs-5/3 had the largest saturated adsorption capacity of HCPT (1013.51 mg g-1) and higher dissolution rate (93.75%).