Cyclophosphazene-Based Hybrid Nanoporous Materials as Superior Metal-Free Adsorbents for Gas Sorption Applications

Cyclophosphazene-based inorganic–organic hybrid nanoporous materials (CHNMs) have been synthesized by a facile solvothermal method. The condensation of pyrrole with the reaction product of phosphonitrilic chloride trimer and 4-hydroxybenzaldehyde resulted in the formation of high-surface-area CHNMs. The maximum specific surface area (SA_BET) of 1328 m² g^–1 with hierarchical pore structures having micropores centered at 1.18 nm and mesopores in the range of 2.6–3.6 nm was estimated from the N₂ sorption analysis. Observation of high SA_BET could be attributed to the synergy effect exerted by the cyclophosphazene moiety owing to its three-dimensional paddle wheel structure. The metal-free adsorbent exhibited a high and reversible CO₂ uptake of 22.8 wt % at 273 K and 1 bar. The performance is on the higher side among the reported metal-free inorganic–organic hybrid nanoporous adsorbents. Moreover, the high H₂ uptake of 2.02 wt % at 77 K and 1 bar is an added advantage. The superior performance of the adsorbents for the gas sorption applications could be attributed to the combined effect of high SA_BET and hierarchical pore structure, which has made CHNMs good candidates for energy and environmental applications

Identifying the Point of Attachment in the Hypercrosslinking of Benzene for the Synthesis of a Nanoporous Polymer as a Superior Adsorbent for High-Pressure CO₂ Capture Application

The point of attachment in the hypercrosslinking of benzene using formaldehyde dimethyl acetal as the crosslinker, anhydrous ferric chloride as the catalyst, and 1,2 dichloroethane as the solvent for the synthesis of poly-benz is reported. A fast microwave-assisted synthesis, within a reaction time of 60 min, resulted in the formation of nanoporous poly-benz having a specific surface area of 1168 m2 g–1. A thorough analysis of poly-benz using 13C cross-polarization magic angle spinning nuclear magnetic resonance and X-ray photoelectron spectra has revealed the hypercrosslinking at the meta position of the benzene ring. The synthesized poly-benz further shows a high CO2 capture capacity of 65.3 wt % at 298 K and 30 bar. Various adsorption isotherm models have been fitted at different temperatures up to 30 bar to represent the equilibrium CO2 adsorption data

Nitrogen-Enriched Nanoporous Polytriazine for High-Performance Supercapacitor Application

Polytriazine with high nitrogen content (c.a. 50.5 wt %) has been synthesized by an ultrafast microwave-assisted method using melamine and cyanuric chloride. The nitrogen-enriched nanoporous polytriazine (NENP-1) has exhibited high specific surface area (maximum SA_BET of 838 m² g^–1) and narrow pore size distribution. The NENP-1 has been employed as electrode material for supercapacitor application. A maximum specific capacitance (C_sp) of 1256 F g^–1 @1 mV s^–1 and 656 F g^–1 @1 A g^–1 are estimated from the cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements, respectively, in a three-electrodes configuration. This C_sp value is considered as very high for a nonmetallic system (organic polymer). Superior capacitance retention of 87.4% of its initial C_sp was observed after 5000 cycles at a current density of 5 A g^–1 and demonstrates its potential as an efficient electrode material for practical applications. To test this claim, an asymmetric supercapacitor device (ASCD) was fabricated. The C_sp values of the device in the two-electrode configuration are 567 F g^–1 @5 mV s^–1 and 287 F g^–1 @4 A g^–1 in the CV and GCD measurements, respectively. The ASCD has shown superior energy density and power density of 102 Wh kg⁻¹ and 1.6 kW kg^–1, respectively, at the current density of 4 A g^–1. The energy density is much higher than the best reported supercapacitors and also close to the commercial batteries. This indicates the material could bridge the gap between the commercial batteries and supercapacitors