A Molecular-Sieving Interphase Towards Low-Concentrated Aqueous Sodium-Ion Batteries

Aqueous sodium-ion batteries are known for poor rechargeability because of the competitive water decomposition reactions and the high electrode solubility.Improvements have been reported by saltconcentrated and organic-hybridized electrolyte designs,however,at the expense of cost and safety.Here,we report the prolonged cycling of ASIBs in routine dilute electrolytes by employing artificial electrode coatings consisting of NaX zeolite and NaOH-neutralized perfluorinated sulfonic polymer.The as-formed composite interphase exhibits a molecularsieving effect jointly played by zeolite channels and size-shrunken ionic domains in the polymer matrix,which enables high rejection of hydrated Na^(+)ions while allowing fast dehydrated Na^(+)permeance.Applying this coating to electrode surfaces expands the electrochemical window of a practically feasible 2 mol kg^(-1) sodium trifluoromethanesulfonate aqueous electrolyte to 2.70 V and affords Na_(2)MnFe(CN)_(6)//NaTi_(2)(PO_(4))_(3) full cells with an unprecedented cycling stability of 94.9%capacity retention after 200 cycles at 1 C.Combined with emerging electrolyte modifications,this molecular-sieving interphase brings amplified benefits in long-term operation of ASIBs.

Grapevine-like high entropy oxide composites boost high-performance lithium sulfur batteries as bifunctional interlayers

Lithium-sulfur batteries(LSBs)with high energy densities have been demonstrated the potential for energy-intensive demand applications.However,their commercial applicability is hampered by hysteretic electrode reaction kinetics and the shuttle effect of lithium polysulfides(LiPSs).In this work,an interlayer consisting of high-entropy metal oxide(Cu_(0.7)Fe_(0.6)Mn_(0.4)Ni_(0.6)Sn_(0.5))O_(4) grown on carbon nanofibers(HEO/CNFs)is designed for LSBs.The CNFs with highly porous networks provide transport pathways for Li^(+) and e^(-),as well as a physical sieve effect to limit LiPSs crossover.In particular,the grapevine-like HEO nanoparticles generate metal-sulfur bonds with LiPSs,efficiently anchoring active materials.The unique structure and function of the interlayer enable the LSBs with superior electrochemical performance,i.e.,the high specific capacity of 1381 mAh g^(-1) at 0.1 C and 561 mAh g^(-1) at 6 C.This work presents a facile strategy for exploiting high-performance LSBs.

Antipoisoning catalysts for the selective oxygen reduction reaction at the interface between metal nanoparticles and the electrolyte

One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction(ORR),significantly deteriorating fuel cell performance.Here,antipoisoning catalysts consisting of Pt-based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed.The pore structure of the carbon shells is systematically regulated at the atomic level by high-temperature gas treatment,allowing O_(2) molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves.Besides,the carbon shell,as a protective layer,effectively prevents metal dissolution from the catalyst during a long-term operation.Consequently,the defect-controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.

Adsorption Mechanisms of Mesoporous Adsorbents in Solutions

Sieve effect, complexation, ionic exchange, electrostatic interaction, hydrogen bonding, hydrophobic interaction, and molecular recognition based on molecular imprinting are comprehensively discussed.

A[Th_(8)Co_(8)]Nanocage-Based Metal–Organic Framework with Extremely Narrow Window but Flexible Nature Enabling Dual-Sieving Effect for Both Isotope and Isomer Separation

The synthesis of nanoporous materials that display a combination of molecular sieving(MS)and quantum sieving(QS)effects is still a challenging task.In this work,we have demonstrated the synthesis of a nanocaged metal–organic framework(MOF),ECUT-8,that has a dual-sieving capability.ECUT-8 afforded H_(2)/D_(2) isotope separation due to its extremely narrow window size(3.0Å),resulting in QS.Further,the framework flexibility of ECUT-8 was exploited for the separation of butane and hexane isomers due to its MS effect.Other desirable features of ECUT-8 include high thermal,water,and chemical stability,making it suitable for practical application.Herein,these results open up an avenue to design the effects of coexistence of multiple sieving in one material.

Separation of hexane isomers by introducing“triangular-like and quadrilateral-like channels”in a bcu-type metal-organic framework

The separation of hexane isomers is of vital importance to produce high quality gasoline in the petrochemical industry.However,the similar vapor pressure and boiling point of hexane isomers bring great difficulties and challenges in the separation process.Sieving effect,which allowing smaller molecules pass through and preventing others,should be a powerful strategy to solve this problem by making good use of porous materials.Therefore,physical separation by metal-organic framework(MOF)materials appears and becomes a burgeoning separation technique in industry.Due to the weak interaction between hexane isomers with absorbents,it puts forward higher requirements for the accurate design of MOF materials with optimal pore system.To address this issue,a novel MOF[Zn_(9)(tba)_(9)(dabco)_(3)]·12DMA-6MeOH(abbreviation:Zn_(9)(tba)_(9)(dabco)_(3);H_(2)tba=4-(1H-tetrazol-5-yl)-benzoic acid;dabco=1,4-diazabicyclo[2.2.2]octane;DMA=N,N-dimethylacetamide)with bcu network has been designed and synthesized by reticular chemistry strategy.Benefiting from the pre-designed topology and suitable linear ligand H_(2)tba and dabco,the structure of Zn_(9)(tba)_(9)(dabco)_(3)exhibits two types of channels with triangular-like and quadrilateral-like geometry.Zn_(9)(tba)_(9)(dabco)_(3)with appropriate channel size and shape displays potential selective adsorption capacity of vapor-phase hexane isomers through sieving effect.Moreover,outstanding gas adsorptive separation properties of Zn_(9)(tba)_(9)(dabco)_(3)could also be speculated by theoretical ideal adsorbed solution theory(IAST),suggesting Zn_(9)(tba)_(9)(dabco)_(3)can be regarded as a potential adsorbent material for purification natural gas_Breakthrough experiments show that Zn_(9)(tba)_(9)(dabco)_(3)is capable of discriminating all four hexane isomers at 298 K,and the corresponding research octane number(RON)of the eluted mixture closes to 95,which is higher than the standard for industrially refined hexane blends(about 83).We speculate that sieving effect and diffusion are a synergetic contributory factor in their elution dynamics,which may be ascribed to temperature-dependent interaction between pore aperture and each isomer.This work presents a typical example for design of efficient MOF absorbents by reticular chemistry strategy.

Enhanced desulfurization performance of hybrid membranes using embedded hierarchical porous SBA-15

The utilization of materials with a hierarchical porous structure as multi-functional additives is highly attractive in the preparation of hybrid membranes.In this study,novel hybrid membranes are designed by embed-ding hierarchical porous Santa Barbara Amorphous 15(SBA-15)with a dual-pore architecture(micropores and mesopores)for pervaporation desulfurization.The SBA-15 with cylindrical mesopores provides molecular transport expressways to ensure improved permeability,while micropores on the wall have molecular sieving effects that are essential for the enhancement of permselectivity of thiophene molecules.Considering thiophene/n-octane mixture as a model system,the hybrid membrane with embedded 6 wt-%SBA-15 exhibits optimal pervaporation desulfurization performance with a permeation flux of 22.07 kg·m^-2·h^-1 and an enrichment factor of 6.76.Moreover,the detailed structure and properties of hybrid membranes are systematically characterized.This study demonstrates the immense potential of hierarchical porous materials as additives in membranes to simultaneously increase permeability and permselectivity.