Xiaojing Zhu,Sha Wang,Wenquan Huang,Yong Tian,Xiufang Wang
Because of the uncontrollable cross-linking rate of carbon precursors and the serious macroscopic phase separation during the organic–organic self-assembly process, the synthesis of mesoporous carbon nanospheres (MCNs) with uniform diameter < 200 nm remains a challenge. In this study, we developed a direct acid-assisted, aqueous self-assembly method to synthesize such uniform MCNs with particle and pore sizes of ∼100 and ∼3.5 nm, respectively, by fine-tuning the volume ratio of ethanol/water under a high concentration of triblock copolymer F127 (7.9 × 10 −4 mol L −1 ). The formation of uniform spheres was affected by the polymerization rate of carbon precursors and macroscopic phase separation, which are closely related to the amount of ethanol and F127. The highly acidic conditions could partially protonate carbon precursors and template, quickly inducing the self-assembly process with resorcinol/formaldehyde as carbon precursors and F127 as a morphology-controlling and interface-stabilizing agent. Because of their high surface area, large pore size, and nanoscaled and uniform spherical characteristics, the obtained MCNs loaded with the poorly water-soluble model drug itraconazole (ITZ) apparently increased the dissolution and release rates of ITZ.
Ultrafine Pt nanoparticles (Pt UPs) were prepared using a stepwise modulation approach, ensuring consistent reaction kinetics throughout each step to achieve uniform size and high dispersion of Pt UPs. The morphology of the Pt nanoparticle was precisely controlled by managing the reaction conditions at each step, thereby enhancing the catalytic activity of the Pt metals. In order to form photoinduced hydrolysis products with different dispersions and particle sizes, two steps were conducted. First, homogeneously dispersed photoinduced hydrolysis products were adsorbed on nitrogen-doped multiwalled carbon nanotubes using ice photochemistry under stabilizer-free conditions. Second, these products were photoinduced by using different wavelengths of light. Subsequent in situ reduction with various reducing agents influenced the composition, particle size, and dispersion degree of the Pt UPs. Furthermore, the subtle charge transfer between the supporter and Pt was adjusted by employing low- and high-temperature nitrogen doping methods, resulting in Pt UPs with electron-deficient and electron-rich charge structures on the surface. This study offers insights into the precise modulation of the Pt nanoscale morphology and reveals the subtle adjustments in charge transfer between the supporter and the metal through nitrogen doping. Additionally, the origin of the catalytic activity of Pt in various reactions was explored.
In this study, a new method of photopolymerization with the dynamic exposure was developed to solve the issue of uneven laser-induced polymerization and prepare nanogels with uniform size. Dynamic exposure was used to divide the photopolymerization process into illumination period and dark period. In illumination period, free radicals were generated to induce polymerization. In the dark period, the incompletely cross-linked nanogels and oligomers were redistributed to homogenize the polymerization system. The double bond conversion of the polymerization in the dynamic exposure mode was equal to that in the conventional exposure mode. The simple dynamic exposure mode optimized the process for preparing the nanogels by laser-induced photopolymerization.
Jiangjiang Luo,Yanbo Yao,Muchuan Niu,Xiaoshuang Duan,Rui Wang,Tao Liu
Because of a wide range of applications of porous carbon platelets (PCPs), a robust method for their facile synthesis/fabrication with controlled porous structure, size, and shape is constantly needed. Herein, we report a simple and scalable method for producing PCPs with uniform size and arbitrarily designed shapes. This approach relies on CO2 laser irradiation to induce carbonization of a biomass composite sheet formed by the infusion of sodium lignosulfonate into a cellulose paper to create porous carbon features with arbitrarily designed shapes. Upon subsequent water immersion treatment, the laser-written carbon features could spontaneously detach to form freestanding PCPs. The PCPs of different shapes were fabricated, characterized, and demonstrated for their potential applications in dye adsorption, as flexible sensors, and as miniaturized supercapacitors. Our method is expected to make great impacts in multiple fields, such as environment, energy storage, sensing, catalysis, and so forth.
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