Search

In this study, the preparation of robust and transparent poly(butenyl sorbate) (PBS) membranes (PBS-R) was studied in terms of their CO2/CH4 separation performance. The organocatalytic group transfer polymerization of butenyl sorbate was used for the synthesis of PBS with a designed molecular weight and a moderate molecular weight distribution. For the first time, facile fabrication of PBS-R was achieved through thiol-ene addition between the butenyl groups of PBS and dithiols under 365-nm ultraviolet irradiation. The mechanical properties and CO2/CH4 separation performance of the PBS-R membranes were controlled by introducing an amino-triazole functional group and regulating the length and bulkiness of the dithiol spacers during thiol-ene addition. The amino and triazole groups of the PBS-R membrane showed high affinity to CO2, thereby increasing the CO2/CH4 permselectivity from 9.18 to 10.8 and the CO2 permeability from 127 to 142 barrer. The effect of tensile strength on CO2 permeability was evaluated by preparing PBS-R membranes using dithiols with two rigid benzene rings as spacers and flexible spacers. In addition, the effect of the spacer structure on the permselectivity of PBS-R was investigated using 1,4-butanedithiol, 2,2′-oxydiethanethiol, 1,8-octanedithiol, 1,4-benzenedithiol, and 4,4′-thiobisbenzenethiol. [ABSTRACT FROM AUTHOR]

The construction of an environmentally friendly and efficient photocatalyst for water splitting and hydrogen evolution can effectively alleviate the pressure of current energy consumption and environmental pollution. Herein, by using first-principles calculations, the MoSiGeN4/SiC heterojunction was studied as a potential photocatalyst. According to different stacking methods, 12 kinds of configurations of such heterojunction with high symmetry were constructed, among which four kinds show excellent stability and hence were further studied. The results show that such heterojunction is Z-scheme heterojunction, which not only has good light absorption efficiency, but also shows excellent performance of photocatalytic water splitting for hydrogen evolution. In addition, one of the stable configurations shows better photocatalytic hydrogen evolution performance than precious metal catalyst Pt, and the Gibbs free energy is only −0.039 eV. It is expected to prepare a hydrogen evolution catalyst with excellent performance. Further, the possible mechanism responsible for the excellent properties of MoSiGeN4/SiC heterojunction in photocatalysis has been revealed. Our research further enriches the theoretical research genealogy of MA2X4 family materials and guides the direction for further rational design of photocatalysts. Schematic diagrams of all studied configurations, catalytic mechanism and HER performance characterization. [ABSTRACT FROM AUTHOR]

Functionalized conjugated microporous polymers (CMPs) containing amino, imino, and hydrazine groups are synthesized by the Sonogashira–Hagihara coupling reaction. Notably, the porosities, thermal stabilities, and morphologies of the CMPs can be controlled by the introduction of functional groups. Here, the relationships between the functional groups and photocatalytic performance are discussed for the first time. The CMP nanowires exhibit excellent photocatalytic performance in organic pollutant degradation: the degradation rate obtained by CMP-I3 bearing naphthalene groups via an imine bond is > 99.99%, and ~ 99.71% of the degradation activity is maintained after five cycles. Notably, the excellent photocatalytic properties of CMP-I3 are imparted by the introduction of the naphthalene groups, which reduced the band gap. The improved charge-transfer activity accounts for the highest and lowest photocurrent intensity and resistance achieved, respectively. Furthermore, the photocatalytic mechanism of CMPs reveals that the superoxide anion is the main active substance in the photocatalytic degradation of dyes. [ABSTRACT FROM AUTHOR]

In this study, BiVO4/CuWO4 nanocomposites with S-scheme heterojunction structure were prepared firstly and the properties were analyzed by various techniques. The sonocatalytic activity was evaluated by the degradation of tetracycline (TET). Under the optimum experimental conditions of initial concentration of TET = 25 mg/L, composite ratio of BiVO4 and CuWO4 = 15%, catalyst addition = 1 g/L, ultrasonic time = 120 min, ultrasonic power = 500 W, pH = 7, the experiment results showed that BiVO4/CuWO4 sonocatalyst removed TET by 81.05 ± 2.92%. K2S2O8 was verified to enhance the sonocatalytic performance of BiVO4/CuWO4 efficiently, and the removal ratio of TET could reach 91.25 ± 1.95% within 120 min by using BiVO4/CuWO4 and K2S2O8. The free radical (ROS) quenching experiment and TA-PL technology proved that the main free radical of degradation was ·OH. The potential sonocatalytic mechanism showed that the enhanced catalytic efficiency was due to the construction of S-scheme heterojunctions, which improved electron–hole pair (e−–h+) separation efficiency and rapid kinetics. The speculated TET degradation route of TET included intermediate products was proposed and four reused experiments proved that BiVO4/CuWO4 had good recyclability. In conclusion, the prepared BiVO4/CuWO4 composites with S-type heterojunction mechanism have more possibilities in wastewater treatment, which provides a helpful guide for the synthesis and application of composite sonocatalysts. [ABSTRACT FROM AUTHOR]

The rapid development of industrialization generated an urgent requirement for the catalytic conversion of CO2 into high-value-added chemical products. Herein, a class of novel bifunctional metalloporphyrin-based hyper-crosslinked ionic polymer (ImHCP-Co) was synthesized via one-pot Friedel–Crafts alkylation and quaternization reactions. The obtained bifunctional ImHCP-Co showed a high BET surface area and sufficient CO2 adsorption capacity. Relying on the synergistic effect of the electrophilic and nucleophilic functionalities, the as-prepared ImHCP-Co showed an excellent performance in CO2 cycloaddition using epichlorohydrin as the substrate (99% conversion and 99% selectivity) and can be carried out without any solvents or cocatalysts to afford a high turnover number. Importantly, it could also convert various epoxide substrates into the corresponding cyclic carbonates and can maintain 82.5% of its catalytic ability after 5 cycles. The catalytic mechanism was systematically explained by DFT calculation and proved the cooperative effect of Co2+ centers and nucleophilic Cl− in the catalytic process. This study provides a new avenue for the design and preparation of HCP-based multifunctional catalysts used for the treatment of greenhouse gases. [ABSTRACT FROM AUTHOR]

Finding efficient and environmentally friendly semiconductor photocatalysts can effectively alleviate the energy crisis and environmental pollution. Based on first-principles calculations, this work focused on the electronic, Bader charge and optical properties of the TMDs/MN heterojunctions. The results showed that the AlN/WS2 and GaN/WS2 heterojunctions are the type-II energy band arrangement, which indicates effective promotion of the separation of the photogenerated electron–hole pairs. Meanwhile, the AlN/WSe2, GaN/WSe2, AlN/MoSe2 and GaN/MoSe2 heterojunctions belonged to the type-I energy band arrangement. The Bader charge results showed that the built-in electric field formed by the heterojunction prevents the recombination of charge carriers. These type-I heterojunctions have excellent optical absorption ability and are suitable for optoelectronic components. Surprisingly, we found that the AlN/WSe2, GaN/WSe2, AlN/MoSe2 and GaN/MoSe2 heterojunctions transform type-I heterojunction to type-II heterojunction by applying electric field. This work further provides the theoretical basis for the design of efficient photocatalysts. [ABSTRACT FROM AUTHOR]

Superhydrophobic conjugated microporous polymer-coated sponges (CMP@sponges) were synthesized in one pot by an in situ Sonogashira coupling reaction of silyl and amino group-containing monomers in the presence of melamine sponges. The water contact angles of the superhydrophobic CMP@sponges reached 154.9°. Introducing a small number of amino groups enhanced the hydrophobicity and stability of the CMP@sponges. The CMP@sponges exhibited a good absorption capacity for various oils (more than 80 times their own weight) and were stable after 10 cycles. An oil collection device was also designed to perform continuous oil separation from water. Gasoline and diesel can be collected at speeds of 16–18 mL/s with an efficiency of 99%. The superhydrophobic CMP@sponges can not only separate oil/water mixtures but can also be used for separating water-in-oil emulsions with an efficiency of approximately 90%. In addition, the CMP@sponges show excellent flame retardancy, which can reduce the risk of fire and explosion and holds great promise for the treatment of flammable fuels and organic compounds. [ABSTRACT FROM AUTHOR]

Four kinds of conjugated microporous polymers (CMPs) with imine structures were synthesized by a Sonogashira coupling reaction followed by a postreaction between aldehydes and amines. Palladium nanoparticles (Pd NPs) were successfully supported on the CMPs to prepare Pd/CMP heterogeneous catalysts and were used to catalyze the Suzuki–Miyaura coupling reaction. The number of aromatic nuclei and nitrogen atoms in the CMPs highly affects Pd loading. In the Suzuki–Miyaura coupling reaction, the Pd/CMP with good Pd NPs dispersibility and appropriate Pd content (Pd/CMP-NA) exhibited the highest catalytic efficiency with 100% conversion and 95.4% yield which can be used for many substrates. The Pd/CMP-NA heterogeneous catalyst was easy to recover and still exhibited good catalytic efficiency after 5 cycles. To further understand the catalytic mechanism of Pd/CMP-NA on the Suzuki–Miyaura coupling reaction, we proposed a rational catalytic cycle. This paper provides an idea for the structural design of CMPs used for Suzuki–Miyaura catalytic reaction. [ABSTRACT FROM AUTHOR]