Composite Flame Retardants Based on Conjugated Microporous Polymer Hollow Nanospheres with Excellent Flame Retardancy.

The development of polymer materials with excellent flame retardancy has been paid increasing attention for their valuable applications in saving energy in modern architecture. Herein, conjugated microporous polymers hollow nanospheres (CMPs-HNS) were prepared by Sonogashira-Hagihara cross-coupling reaction with 1,3,5-triacetylenebenzene, 3-amino-2,6-dibromopyridine, and 2,4,6-tribromoaniline as building blocks using SiO2 nanoparticles as hard templates. To enhance the flame-retardant performance of the CMPs-HNS, antimony pentoxide solution (Sb2O5) and bisphenol A-bis (diphenyl phosphate) (BDP) were coated onto the as-prepared CMP-HNS (CMPs-HNS-BSb) by a simple immersion method. The peak heat release (pHRR) from microscale combustion colorimeter (MCC) of CMPs-HNS-BSb was 76.5 and 73.05 W g-1, respectively. By introducing CMPs-HNS-BSb into the epoxy resin (EP) matrix, the CMP2-HNS-BSb/EP (0.5) composites show that the pHRR values were 809.3 and 645.2 kW m-2, reduced by 21% as measured by conical calorimetry (CC), and total heat release (THR) reduced by 29.7%, going from 101 to 70.8 MJ/m2 when compared to the pure sample. Besides, total smoke production (TSP) reduced about 23.7%. The hollow structure can enhance the thermal insulation performance. As measured, the thermal conductivity of CMP1-HNS-BSb and CMP2-HNS-BSb is 0.044 and 0.048 W m-1 K-1. Based on the advantages of simple manufacture, superior thermal insulation, and flame retardancy, our CMPs-HNS-BSb/EP composites may find useful applications in various aspects such as building energy saving in future development.

Non-Precious Metal-Doped Carbon Materials Derived From Porphyrin-Based Porous Organic Polymers for Oxygen Reduction Electrocatalysis.

The cathodic oxygen reduction reaction (ORR) is important in the development of renewable energy devices, to produce novel and non-precious metal catalysts with high electrocatalytic activity to reduce the consumption of non-renewable platinum (Pt) catalyst. In this work, we developed N-doped and Fe/N dual-doped porous carbons as catalysts for ORR simply by high-temperature pyrolysis of porphyrin-based conjugated microporous polymers (CMPs). By combination of heteroatom doping, highly porous structure and tubular morphology, the as-prepared carbon samples exhibited high electrocatalytic activity with 4-electron transfer mechanism, nearly close to the commercial Pt/C catalyst. In particular, among these samples, the Fe/N-CMP-1000 displayed a higher onset potential (0.95 eV), positive half-wave potential (0.85 eV) and limiting current density value (5.1 mA cm-2 ) as well as good durability and better methanol tolerance contrasting with Pt/C catalyst, suggesting that the as-prepared metal-free catalysts from porphyrin-based CMPs show great potential for ORR.

Nitrogen-doping hollow carbon nanospheres derived from conjugated microporous polymers toward oxygen reduction reaction.

The exploitation non-precious or metal-free electrocatalysts of oxygen reduction reaction (ORR) is of significance for construction of next-generation fuel cells. In this work, hollow-spherical conjugated microporous polymers (CMPs) comprising porphyrin units were synthesized as precursors to prepare N-doping porous carbon spheres (CMP-NP-x) by a direct pyrolysis method. The as-resulted CMP-NP-x exhibited spherical morphology with hollow structure similar to that of CMPs precursors. The BET surface area of CMP-NP-x can be tailored by the pyrolysis temperature varying from 868 m2 g-1 to 1118 m2 g-1. According to XPS analysis, the pyrrolic N content in the sample decreased but the graphitic N and pyridinic N increased with increasing of the pyrolysis temperature from 800 °C to 1000 °C. Taking advantages of porous structure with large accessible surface areas and N species active sites, the resulting CMP-NP-x showed superior ORR activity and methanol tolerance to commercial Pt/C catalyst. In particular, CMP-NP-900 possesses the highest onset potential (0.930 V), half-wave potential (0.857 V) and limiting current density of 4.45 mA cm-2, compared with Pt/C catalyst and other samples, making it a promising metal-free catalyst superior to commercial Pt/C catalyst in alkalic condition.

Facile Preparation of a Carbon-Based Hybrid Film for Efficient Solar-Driven Interfacial Water Evaporation.

Solar-driven interfacial water evaporation is one promising technology for seawater desalination and sewage purification because it offers a feasible and sustainable strategy to relieve global water scarcity. Herein, a novel hybrid film composed of recycled carbon soot and poly(vinyl alcohol) is developed by a very simple, green, and highly scalable "salt-assisted" assembling method. The hybrid film possesses characteristics with a porous structure, superhydrophilicity, ∼100% light absorption, and low thermal conductivity, which can effectively convert light into heat under solar illumination. Consequently, the hybrid film can achieve a photothermal conversion efficiency of 91.5% under a stimulated solar irradiation of 1 kW m-2. Furthermore, the hybrid film can be applied for seawater desalination and dye wastewater purification. The findings of our work not only provide a new photothermal platform with high light-to-thermal conversion ability and good reusability but also open a new avenue for the applications of carbon soot-based hybrid films in solar-assisted water evaporation and sewage purification.

Photothermal Conversion Material Derived from Used Cigarette Filters for Solar Steam Generation.

Solar steam generation by photothermal materials has recently emerged as a new and feasible approach to effectively harvest solar energy in a variety of applications. This work reports an efficient heat localization material based on the renewable cellulose acetate cigarette filters and a reduced graphene oxide coating (RGO-CF) as the light-to-heat conversion layer for solar steam generation. RGO-CF possessed an aligned structure with superhydrophilic nature, lower thermal conductivity (0.0733 Wm-1 K-1 ), and broad light adsorption (≈100 %). These characteristics enable rapid water transportation and excellent light-to-heat conversion by the resulting RGO-CF with an energy conversion efficiency of 94 % under stimulated solar illumination (1 kW m-2 ), which demonstrates that RGO-CF is a promising photothermal conversion material for solar steam generation. Such strategy for preparation of photothermal materials not only reduces the fabrication cost but also provides a fundamental guidance for the practical application of renewable polymer resources from used cigarette filters.

Novel N-rich porous organic polymers with extremely high uptake for capture and reversible storage of volatile iodine.

The imino group-contained porous organic polytriphenylamine, which originated from diphenylamine and 1,3,5-tris(4-bromophenyl)benzene, was designedly synthesized though Buchwald-Hartwig coupling reaction. The basic properties including morphologies, structure and thermal stability of the resulting POPs were investigated by scanning electron microscope(SEM), thermo gravimeter analysis (TGA), 13C CP/MAS solid state NMR and Fourier transform infrared spectroscope (FTIR). The pore size distribution of POPs present uniform mesoporous of sizes less than 50nm. Scanning electron microscope images show that the resulting POPs formed as an aggregation composed of nanospheres. The POPs were employed as a physicochemical stable porous medium for removal of radioactive iodine and an iodine uptake of up to 382wt% was obtained. To our knowledge, this is one of the highest adsorption value reported to date. Based on these findings, the resulting POPs shows great potential in the removal of radioactive iodine at different states, through a green, environmentally friendly, and sustainable way.