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Selective-adsorption separation is an energy-efficient technology for the capture of acetylene (C2H2) from carbon dioxide (CO2) and ethylene (C2H4). However, it remains a critical challenge to effectively recognize C2H2 among CO2 and C2H4, owing to their analogous molecule sizes and physical properties. Herein, we report a new microporous metal–organic framework (NUM-14) possessing a carefully tailored pore system containing moderate pore size and nitro-functionalized channel surface for efficient separation of C2H2 from CO2 and C2H4. The activated NUM-14 (namely NUM-14a) exhibits sufficient pore space to acquire excellent C2H2 loading capacity (4.44 mmol g−1) under ambient conditions. In addition, it possesses dense nitro groups, acting as hydrogen bond acceptors, to selectively identify C2H2 molecules rather than CO2 and C2H4. The breakthrough experiments demonstrate the good actual separation ability of NUM-14a for C2H2/CO2 and C2H2/C2H4 mixtures. Furthermore, Grand Canonical Monte Carlo simulations indicate that the pore surface of the NUM-14a has a stronger affinity to preferentially bind C2H2 over CO2 and C2H4 via stronger C-H···O hydrogen bond interactions. This article provides some insights into customizing pore systems with desirable pore sizes and modifying groups in terms of MOF materials toward the capture of C2H2 from CO2 and C2H4 to promote the development of more MOF materials with excellent properties for gas adsorption and separation. [ABSTRACT FROM AUTHOR]

Selective-adsorption separation is an energy-efficient technology for the capture of acetylene (C2H2) from carbon dioxide (CO2) and ethylene (C2H4). However, it remains a critical challenge to effectively recognize C2H2 among CO2 and C2H4, owing to their analogous molecule sizes and physical properties. Herein, we report a new microporous metal–organic framework (NUM-14) possessing a carefully tailored pore system containing moderate pore size and nitro-functionalized channel surface for efficient separation of C2H2 from CO2 and C2H4. The activated NUM-14 (namely NUM-14a) exhibits sufficient pore space to acquire excellent C2H2 loading capacity (4.44 mmol g−1) under ambient conditions. In addition, it possesses dense nitro groups, acting as hydrogen bond acceptors, to selectively identify C2H2 molecules rather than CO2 and C2H4. The breakthrough experiments demonstrate the good actual separation ability of NUM-14a for C2H2/CO2 and C2H2/C2H4 mixtures. Furthermore, Grand Canonical Monte Carlo simulations indicate that the pore surface of the NUM-14a has a stronger affinity to preferentially bind C2H2 over CO2 and C2H4 via stronger C-H···O hydrogen bond interactions. This article provides some insights into customizing pore systems with desirable pore sizes and modifying groups in terms of MOF materials toward the capture of C2H2 from CO2 and C2H4 to promote the development of more MOF materials with excellent properties for gas adsorption and separation.

Moderate pore size and (O=)C-O-Mn bonds are designed in Mn 3 O 4 nanoflakes/reduced graphene oxide composites to enhance the specific capacitance and cycling performance of electrodes for supercapacitors. Manganese oxide nanoflakes grow on the surface of graphene oxides via chemical precipitation. After annealing, (O=)C-O-Mn bonds are formed between Mn 3 O 4 and graphene to enhance structural stability of electrode materials. Moreover, the pore size in Mn 3 O 4 enlarges with the increased annealing temperature driven by phase transition and lattice reforming. The moderate pore size of 5–10 nm in Mn 3 O 4 contributes to electrolyte ion diffusion and improves the capacitive-controlled energy storage. In three-electrode system, Mn 3 O 4 nanoflakes/reduced graphene oxide composites with optimal pore size of 5–10 nm and (O=)C-O-Mn bond deliver high specific capacitance (351 F g−1 at 0.5 A g−1) and good cycling performance (80.1% of maximum capacitance after 10,000 cycles). To probe practical applications, Mn 3 O 4 nanoflakes/reduced graphene oxide composites and active carbon are employed as positive electrode and negative electrode, respectively, to assemble asymmetrical supercapacitors. This asymmetrical supercapacitor demonstrates high energy density (36.76 Wh kg−1) and good cycling performance (93.5% after 5000 cycles). • The moderate pore size in Mn 3 O 4 is optimized by controlling annealing temperature. • (O=)C-O-Mn bonds are formed and characterized by FTIR and XPS spectra. • The composites display excellent specific capacitance and cycling life. [ABSTRACT FROM AUTHOR]