•Poly(arylene ether) and polyamide based single ion conducting polymer electrolytes were comparatively studied.•The flexible poly(arylene ether) based backbone is apt to form a dense and uniform blend film in comparison with the rigid polyamide based backbone.•The ether segments in poly(arylene ether) facilitates the lithium ion conduction in the polymer matrix.•Gel-type LiPHFE blend polymer electrolyte is able to construct compatible and stable electrochemical interface.Effect of polyamide and poly(arylene ether) as backbones of bis(benzene sulfonyl)imide for single ion conducting polymer electrolytes on mechanical and electrochemical properties and device performance was investigated. Alternating copolymerization between 4,4′-fluorine bis(benzene sulfonyl)imide and 4,4′-dihydroxydiphenyl ether produced a poly(arylene ether) based polymer (LiPHFE). For comparison, 4,4′-dicarboxyl bis(benzene sulfonyl)imide was used to copolymerize with 4,4′-diaminodiphenyl ether to form a polyamide based polymer (LiPACA). Thermal stability, morphology, mechanical strength, electrochemical stability and battery performance were carefully measured. We conclude that the LiPHFE blend film is superior to the LiPACA blend film. Half-cells using LiFePO4 (LFP) and Li4Ti5O12 (LTO) incorporating the LiPHFE film as the electrolyte as well as the separator were tested separately at 1 C for 800 cycles. No obvious performance decay was observed, demonstrating exceptional device compatibility and stability. Finally, a full cell with the configuration of “LTO | LiPHFE | LFP” was assembled and subsequently tested at 0.5 C for 100 cycles. The device is capable of delivering a stable discharge capacity of 96 mAh g−1 normalized to the mass of LFP with the coulombic efficiency of 100%. This work paves a way for design of more robust single ion conducting polymer electrolytes to enable batteries to be operative with long cycle life and superior device safety.

•Single ion conductive sodium ion battery enabled by a single ion conducting polymer electrolyte•Ionic conductivity of 0.91 × 10− 4 S cm− 1 with a sodium ion transference number of 0.83•Discharge capacity of 81.4 mAh g− 1 at 0.2C at 20 °C and 89.4 mAh g− 1 at 0.2C at 80 °CA single ion conducting sodium ion battery was fabricated and its operability at 20 °C and 80 °C was successfully demonstrated. In the battery device, sodium ion transport was mediated by a polymer electrolyte membrane based on a sodium ion exchanged poly(bis(4-carbonyl benzene sulfonyl)imide-co-2.5-diamino benzesulfonic acid) macromolecule (NaPA). The cathode material Na3V2(PO4)3 was synthesized using a calcination method, while a sodium metal foil was used as the anode. The PVDF-HFP blended NaPA membrane served as a separator as well as an electrolyte. The NaPA ionomers were introduced into the cathode to replace PVDF to form well-constructed sodium ion transport channels to reduce internal ion transport resistance and interfacial resistance. The ionic conductivity of the NaPA blend film was 0.91 × 10− 4 S/cm at 20 °C and 4.1 × 10− 4 S/cm at 80 °C, on the same order of magnitude of Na-Nafion. The half-cell delivered around 70% of its theoretical reversible specific capacity at 0.2C.

•Electrostatic repulsion together with an overall sealed electrode configuration.•Ionic conductivity of the single ion polymer electrolyte is 0.57 mS cm−1.•The polyether backbone is more compatible with ether based electrolyte.•Capacity retention of 800 mAh g−1 at 2 C after 500 cycles.A cathode was prepared by sealing a carbon supported sulfur electrode inside a composite ion-selective net made of carbon, binder and lithiated ionomer to restrict shuttling of polysulfide anionic species. As a result, the soluble polysulfide anions become unable to escape from the composite ion-selective films due to the electrostatic repulsion between the immobilized single ion conducting ionomers and the polysulfides with no dead angles. Experimentally, lithiated 4,4′-difluoro bis(benzene sulfonyl)imide and PEG200 were copolymerized to form a polyether based single ion conducting polymer. The ionic conductivity of the blend film made of ionomer and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) at a mass ratio of 1:1 is 0.57 mS cm−1 at room temperature. The battery capacity with the sealed sulfur electrode is 1412 mAh g−1 at 0.5 C, 1041 mAh g−1 at 1.0 C, 873 mAh g−1 at 2.0 C and 614 mAh g−1 at 5.0 C, significantly better than the results with lithiated Nafion especially at high C rates. In addition, a long cycling test at 2 C for 500 cycles gives rise to a stable capacity of 800 mAh g−1. The intrinsic electrostatic repulsion between polysulfide anions and the negatively charged electrolyte film, together with the overall sealed electrode configuration, is responsible for blocking the shuttling of polysulfides effectively.

•A facile synthesis of highly cross-linked PTF-M (M = Cr, Mg) complexes with exposed metal sites.•Ambient temperature hydrogen storage capacity of 1.5 wt% at 100 atm with Qst of 11.5 kJ mol−1.•High storage capacity arising from the electrostatic force between the exposed metal sites and the σ-electrons of H2.Cross-linked porous polymeric complexes with exposed metal sites are synthesized for room temperature hydrogen storage via physisorption. At 298 K and 100 atm, PTF-Cr exhibits high excess hydrogen storage capacity up to 1.5 wt% with Qst of 11.5 kJ mol−1 while PTF-Mg exhibits 0.5 wt% with Qst of 8 kJ mol−1. The result provides insight for development of future storage materials with exposed transition metals.We demonstrate a facile synthesis of highly cross-linked polymeric complexes with exposed metal sites for room temperature hydrogen storage via physisorption. At 298 K and 100 atm, PTF-Cr exhibits excess hydrogen storage capacity up to 1.5 wt% with Qst of 11.5 kJ mol−1 while PTF-Mg exhibits 0.5 wt% with Qst of 8 kJ mol−1.Download high-res image (135KB)Download full-size image

•Mesoporous MoO3 is an effective catalyst in the N-ethylcarbazole hydrogenation.•Pd/MoO3 is superior in the catalytic conversion of Octahydro-N-ethylcarbazole.•The superior activity is due to enhanced H spillover and increased H in HxMoO3.Mesoporous MoO3 shows an apparent activity in the catalytic hydrogenation of N-ethylcarbazole (NEC), where a significant amount of tetrahydro-N-ethylcarbazole (4H-NEC) and perhydro-N-ethylcarbazole (PNEC) are detected with the hydrogen uptake of 0.97 wt% after 6 h when the temperature rises to 220 °C. 0.5 wt% Pd/MoO3 catalyst shows a superior catalytic efficiency than the traditional precious metal catalysts 0.5 wt% Ru/Al2O3 and 0.5 wt% Pd/Al2O3, especially in the conversion of Octahydro-N-ethylcarbazole (8H-NEC) to PNEC. The hydrogenation mechanism of MoO3 is completely different from the traditional precious metal catalysts. With the presence of a small amount of Pd, the breaking of HH bond is greatly accelerated, result in the promotion of hydrogen spillover rate and the increase of the concentration of hydrogen molybdenum bronze HxMoO3, which improves the catalytic efficiency of the MoO3 catalyst. Rise the temperature also helps increasing the concentration of H in HxMoO3.Download high-res image (245KB)Download full-size image

We present critical comments on a recent article entitled “Efficiency analysis of novel Liquid Organic Hydrogen Carrier technology and comparison with high pressure storage pathway” (Int. J. Hydrogen Energy 41, 18062, 2016). A careful analysis on the energy efficiency of the hydrogen storage methods based on compressed gas and liquid organic hydrogen carrier technologies is of fundamental importance for making a rational choice of storage techniques to be used for onboard automotive applications.

We present a first-principles study on the dissociative reaction of mono(alkylamino)silane precursors with different sizes of alkylamino ligands on a hydroxylated SiO2 (001) surface. The adsorption energies (ΔEAD), reaction energy barriers (ΔEa), and desorption energies (ΔEDE) of by-products for the six chosen precursors were compared and their ALD windows of temperature were estimated. The results indicate that the dissociative reactions of all six precursors are energetically favorable and DMAS, DEAS, DPAS, DIPAS and DSBAS are appropriate for low temperature deposition with relatively wide ALD windows. In addition, the analysis of reaction rate constants suggests that DMAS, DEAS, DPAS and DIPAS can be used to grow SiO2 thin films with a high deposition rate. Due to the higher reaction rate constants and wider ALD windows of DPAS and DIPAS, they are the most appropriate precursors for ALD at low temperature. These findings underscore the important role of substitution groups in the precursors and suggest ways for designing better precursors for deposition of conformal, dense, and high-purity thin films via ALD processes.

We present a first-principles study on the dissociative reaction of mono(alkylamino)silane precursors with different sizes of alkylamino ligands on a hydroxylated SiO2 (001) surface. The adsorption energies (ΔEAD), reaction energy barriers (ΔEa), and desorption energies (ΔEDE) of by-products for the six chosen precursors were compared and their ALD windows of temperature were estimated. The results indicate that the dissociative reactions of all six precursors are energetically favorable and DMAS, DEAS, DPAS, DIPAS and DSBAS are appropriate for low temperature deposition with relatively wide ALD windows. In addition, the analysis of reaction rate constants suggests that DMAS, DEAS, DPAS and DIPAS can be used to grow SiO2 thin films with a high deposition rate. Due to the higher reaction rate constants and wider ALD windows of DPAS and DIPAS, they are the most appropriate precursors for ALD at low temperature. These findings underscore the important role of substitution groups in the precursors and suggest ways for designing better precursors for deposition of conformal, dense, and high-purity thin films via ALD processes.

Correction for ‘Melamine–terephthalaldehyde–lithium complex: a porous organic network based single ion electrolyte for lithium ion batteries’ by Rupesh Rohan et al., J. Mater. Chem. A, 2015, 3, 5132–5139.

A hyperbranched conjugated Schiff base polymer network was synthesized by condensation between 4,4′,4′′-nitrilotribenzaldehyde and p-phenylenediamine. The material exhibits excellent rate capability and long cycle life for lithium storage. Coupled with lower electrode potential (0.7 V vs. Li+/Li), it may be well suited for fully flexible thin film polymeric batteries as the negative electrode.

It is challenging to introduce pendent sulfonic acid groups into modularly built crystalline porous frameworks for intrinsic proton conduction. Herein, we report the mechanoassisted synthesis of two sulfonated covalent organic frameworks (COFs) possessing one-dimensional nanoporous channels decorated with pendent sulfonic acid groups. These COFs exhibit high intrinsic proton conductivity as high as 3.96 × 10–2 S cm–1 with long-term stability at ambient temperature and 97% relative humidity (RH). In addition, they were blended with nonconductive polyvinylidene fluoride (PVDF) affording a series of mixed-matrix membranes (MMMs) with proton conductivity up to 1.58 × 10–2 S cm–1 and low activation energy of 0.21 eV suggesting the Grotthuss mechanism for proton conduction. Our study has demonstrated the high intrinsic proton conductivity of COFs shedding lights on their wide applications in proton exchange membranes.

•Charge delocalized sp3 boron based single ion conducting polymer electrolyte was prepared.•PEO/SIPE based all-solid-state lithium ion battery displays battery operation at 50 °C.•The PEO/SIPE blended membrane presumably presented two Li+pathways.The ionic conductivity decay problem of poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) when increase the lithium salt of the SPEs up to high concentration is here functionally overcome by the incorporation of a charge delocalized sp3 boron based single ion conducting polymer electrolyte (SIPE) with poly(ethylene oxide) to fabricate solid-state sp3 boron based SIPE membranes (S-BSMs). By characterizations, particularly differential scanning calorimeter (DSC) and ionic conductivity studies, the fabricated S-BSMs showed decreased melting points and increased ionic conductivity as steadily increase the content of sp3 boron based SIPE, which significantly improved the low temperature performance of the all-solid-state lithium batteries. The fabricated Li | S-BSMs | LiFePO4 cells exhibit highly electrochemical stability and excellent cycling at temperature below melting point of PEO, which has never been reported so far for SIPEs based all-solid-state lithium batteries.

•Propose a novel concept of hierarchical proton conductive channel (HPCC) for PEM.•Tune HPCC by simply changing the position of two amine groups in the monomers.•Methanol permeation of the membrane was reduced by ca. 60%.•Tensile strength was increased by 120%.A concept of hierarchical proton conductive channel (HPCC) capable of simultaneously boosting proton conductivity and fuel-permeation resistivity is proposed and the HPCC is optimized to improve the performance of the hyperbranched polyamide proton exchange membrane. The HPCC built in-situ in the membrane can be tuned by simply changing two amine groups from the meta-position to the para-position in the monomers. We demonstrate that the small structural difference between the two monomers may result in remarkable differences in mechanical and electrochemical properties upon polymerization, which enable significantly improved performance of direct methanol fuel cells.

•A facile method to adjust the proton conductive channel.•Great proton conductivity and methanol permeation resistivity were obtained.•Mechanical strength can be improved.A highly efficient methanol resistive organic–organic hybrid polyamide proton exchange membrane was prepared via a facile method and the proton conductive channels (PCCs) in the membrane were optimized to adjust the proton conductivity, mechanical stability and methanol permeability. The hybrid membrane with the optimized PCCs exhibits remarkable proton conductivity of 0.232 S/cm at 80 °C, much higher than the value of a Nafion 117 membrane (0.192 S/cm). At the same time, the methanol permeability of the optimized membrane becomes as low as 6.21 × 10−7 cm2/s, one order of magnitude smaller than that of the Nafion 117 membrane. The tensile strength of the membrane is 13 MPa, comparable to that of the Nafion 117 membrane. This hybrid membrane is therefore promising for applications in direct methanol fuel cell (DMFC).

•Concept of bi-functional polymeric nano-sieve was proposed.•Proton conductivity and methanol permeation resistivity improved simultaneously.•Selectivity of the Nafion composite membrane was nearly doubled.A polyamide macromolecular proton conductor with COOH end-capped is used as a bi-functional polymeric nano-sieve (BFPS) in composite Nafion membranes to simultaneously improve the proton conductivity and suppress the methanol permeation. With 1%–5% incorporation of the BFPS into the composite Nafion membrane, not only the proton conductivity and the methanol-permeation resistivity are improved, but also stronger mechanical strength is obtained, compared to the pure Nafion membrane. We show that the membrane with a 5% BFPS content gives the optimal performance and the composite membrane is well suited for applications in direct methanol fuel cells (DMFCs). The DMFC performance of the membrane is found to be more than 60% better than the performance of a recast pure Nafion membrane.

•Ordered mesoporous MoO3 materials were synthesized via hard-template method.•High specific surface area (up to 142 m2/g) and tunable pore size (6.0–12.7 nm).•The MoO3 shows excellent catalytic activity for cyclohexene hydrogenation.•The superior activity is due to enhanced H spillover and increased H in HxMoO3.Mesoporous transition metal oxides have gained an increasing interest as alternatives to precious metal catalysts for hydrogenation of unsaturated organic molecules. However, the synthesis of a highly crystalline mesoporous transition metal oxide with a high surface area and an ordered pore structure still presents a major technical challenge. Herein, we report the synthesis of a series of well-ordered mesoporous molybdenum oxide (MoO3) complexes via a nanocasting route using cubic mesoporous silica KIT-6 as a template. The catalytic activity of these materials was probed using cyclohexene hydrogenation as a model system. The as-synthesized mesoporous MoO3 materials exhibit crystalline frameworks, high surface areas up to 142 m2/g, and uniform and tunable pore sizes in the range of 6.0–12.7 nm. The mesoporous MoO3 catalysts display excellent catalytic activity with 100% conversion in 6 h, much higher than that of bulk MoO3. The mesostructure and the high surface area enable the reaction to proceed with an enhanced hydrogen spillover rate and an increased concentration of hydrogen bronze.

Construction of effective proton transport channels in proton exchange membranes is the key to the design of high performance proton conductive materials. Enhancement of proton conductivity of polymer electrolyte membranes was achieved by broadening the proton transfer channels via attaching acid groups to both long and short side chains of polymer electrolytes simultaneously. To demonstrate the effectiveness of the uneven side chains on the conductive properties of polymer membranes, three types of polyamide based electrolyte membranes with long side chains, short side chains and long/short side chains were prepared. It was found that among the three types of membranes with the same ion exchange capacity (IEC) value, the one with uneven side chains exhibits the highest proton conductivity. An increase of the IEC value in the uneven side chain membrane leads to a significant increase of proton conductivity. The study provides useful insight into the structural design of polymer electrolyte materials with high conductivity for fuel cell applications.

We report the design and synthesis of an inherently porous single ion conducting gel electrolyte made from a pre-lithiated phloroglucinol-terephthalaldehyde 3D framework for lithium ion batteries, adopting a “bottom-up” approach. The cationic transference number of the membrane obtained by blending the complex with PVDF–HFP followed by solution casting was found to be 0.86, close to unity. The mobile lithium ions shuttle through the low resistant pathways offered by the 3D network by virtue of its high porosity. The electrolyte offers a high ionic conductivity of 6.3 × 10−4 S cm−1 at room temperature (22 °C), comparable to the values of most gel polymer electrolytes. Furthermore, the electrolyte membrane displays high thermal stability and good mechanical strength. Coin cells assembled with the membrane perform well at both room temperature and 80 °C.

Nanoparticle catalysts consist of hundreds or thousands of atoms with structures that are essentially unknown. First-principles-based quantum mechanical calculations on this scale of substance would be prohibitively expensive to perform. Consequently, it has become common to use studies of small clusters at the subnano scale to gain insight into the chemical reactivity of nanoparticle catalysts. Recent theoretical and experimental investigations, however, have found that hydrogen reactivity on small Pt clusters is sensitive to the charge states of the clusters. This finding is in contrast to expectations about the reactivity of nanoparticles and casts doubt on whether small clusters can indeed be used to model realistic catalysts. The present case study for Pt clusters provides a systematic analysis of the charge sensitivity of the key catalytic properties for hydrogenation and clarifies the conditions for which a subnanoscale model may be expected to provide meaningful insights into the behavior of nanoparticle catalysts.Keywords: catalysts; cluster charge states; hydrogenation; platinum; subnano clusters

We report a polysiloxane based single-ion conducting polymer electrolyte (SIPE) synthesized via a hydrosilylation technique. Styrenesulfonyl(phenylsulfonyl)imide groups were grafted on highly flexible polysiloxane chains followed by lithiation. The highly delocalized anionic charges in the grafted moiety give rise to weak association with lithium ions in the polymer matrix, resulting in a lithium ion transference number close to unity (0.89) and remarkably high ionic conductivity (7.2 × 10−4 S cm−1) at room temperature. The high flexibility arising from polysiloxane enables the glass transition temperature (Tg) to be below room temperature. The electrolyte membrane displays high thermal stability and a strong mechanical strength. A coin cell assembled with the membrane comprised of the electrolyte and poly(vinylidene-fluoride-co-hexafluoropropene) (PVDF-HFP) performs remarkably well over a wide range of temperatures with high charge–discharge rates.

Cationic transference number and ionic conductivity of an electrolyte are among the key parameters that regulate battery performance. In the present work, we introduce a novel concept of using porous organic frameworks as a single ion-conducting electrolyte for lithium ion batteries. The synthesized lithium functionalized melamine–terephthalaldehyde framework (MTF–Li), a three dimensional porous organo–lithium complex, in a medium of organic solvent exhibits ionic conductivity comparable to the values of typical gel polymer electrolytes, and the battery cell assembled with the membrane of the material performs at both room temperature and at 80 °C. The rigid three-dimensional framework, functioning as the anionic part of the electrolyte, reduces the anionic transference number to a minimum. As a consequence, the cationic transference number increases to 0.88, close to unity. In addition, by virtue of its synthesis procedure, the electrolyte displays excellent sustainability at high temperatures, which is important for battery safety as well as for enhancing the performance and longevity of the battery.

We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

•Construction of ion transport network with lithiated single ion conducting polymer ionomers.•Charge delocalized anion-incorporated polymer electrolyte with Mn close to 60,000.•Ionic conductivity of 0.14 mS cm−1 at room temperature with t+ = 0.92.•Discharge capacity of 165 mAh g−1 at 0.2C and 123 mAh g−1 at 0.5C at room temperature.We demonstrate a novel method to construct a lithium ion transport network in cathode materials by replacing PVDF with lithiated poly(bis(4-carbonyl benzene sulfonyl)imide-co-bis(4-amino benzene sulfonyl)imide) as the binder. The single ion conducting polymer was synthesized via polycondensation of bis(4-carbonyl benzene sulfonyl)imide and bis(4-amino benzene sulfonyl)imide followed by lithium ion exchange. By blending the ionomers with LiFePO4 and acetylene carbon, the ionic network was well constructed, resulting in a maximum use of active cathode material inside the cathode. The membrane of the polymer electrolyte exhibits an ionic conductivity of 0.14 mS cm−1 at room temperature, a high ion transference number of 0.92 and a wide electrochemical window of 4.5 V (vs. Li+/Li). A lithium ion battery assembled with the single ion conducting polymer electrolyte delivers excellent performance at room temperature with various C-rates.

We design and successfully synthesize non-fluorinated polyamides with controlled crosslinking using sulfonimide as a bi-functional linker to interconnect polymer backbones and as a bridge for proton conduction. We show that the bi-functional linkers are highly beneficial not only for mechanical enforcement of the proton exchange membranes but also for enhancement of water retention capacity. With an appropriate degree of crosslinking, higher water retention capacity than that of commercial Nafion membranes can be obtained. The maximum proton conductivity of the membranes is found to be as high as 0.139 S cm−1 at 80 °C, almost the same as that of a Nafion 117 membrane. Excellent performance with the bi-functional polymer membranes in an air-breathing direct methanol fuel cell prototype, comparable to the performance of a Nafion 117 membrane, is demonstrated.A polymer proton conductor crosslinked with bi-functional sulfonamide bridges is synthesized for PEM fuel cell applications. The architecture simultaneously enhances mechanical strength and improves water retention of the PEMs. With an appropriate degree of crosslinking, the bi-functional PEM exhibits comparable performance to that of a commercial Nafion membrane tested in a direct methanol fuel cell.

Many applications of Sn-doped indium oxide (ITO) films in organic electronics require appropriate surface modifications of ITO nanocrystals with small organic molecules, such as silanes, phosophonic acids and carboxylic acids, to improve interfacial contacts and charge transfer. Here, we propose a new surface modification strategy via adsorption of acetylene molecules on an oxygen-terminated ITO(100) surface using a slab crystalline model to represent the nanocrystal surface. The adsorption was first studied using density functional theory. It was found that the chemisorption of C2H2 on two types of surface oxygen dimers is highly exothermic with the calculated adsorption energies of 3.80 eV and 5.19 eV, respectively. Electron population analysis reveals the origin of the strong interaction between the adsorbate and the ITO(100) surface. Experimental studies on the synthesized ITO nanocrystals using X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy confirm the predicted strong adsorption of C2H2 on ITO surfaces.

Hydrogenation of unsaturated organosulfur compounds is an essential process through which these species are converted into cleaner and more useful compounds. Hydrogen bronze materials have been demonstrated to be efficient catalysts in hydrogenation of simple unsaturated compounds. Herein, we performed density functional theory calculations to investigate hydrogenation of thiophene on hydrogen tungsten bronze. Various reaction pathways were investigated and the most favourable routes were identified. Our results suggest that the reaction proceeds with moderate barriers, and formation of tetrahydrothiophene is facile both thermochemically and kinetically. The present study provides a useful insight into the design of hydrogenation thiophene and its derivatives and effective hydrodesulfurization catalysts.

•A new hydrogen carrier has been reported for the first time.•The carrier itself and its hydrogenated products are liquid at room temperatures.•Fully hydrogenation and dehydrogenation can be achieved at relatively mild conditions.•The purity of hydrogen gas released in the dehydrogenation was found to be high.Hydrogenation of N-ethylindole was investigated over a 5 wt% Ru/Al2O3 catalyst in the temperature range of 160–190 °C at 9 MPa. The process was found to undergo the sequential steps of N-ethylindole → 2H-N-ethylindole → 4H-N-ethylindole → 8H-N-ethylindole with rapid consumption of all intermediate species. The reverse process, dehydrogenation of octahydro-N-ethylindole, was subsequently conducted for tests over a 5 wt% Pd/Al2O3 catalyst in the same temperature range. Full dehydrogenation can be achieved with a moderate reaction rate. The released H2 gas was found to be of a high purity. Our results indicate that N-ethylindole is a promising new member of liquid organic hydrogen carrier family.

A two-dimensional (2D) metal–organic framework (MOF) named NUS-5 was synthesized using a bi-functional ligand 4-pyrazolecarboxylic acid (PyC) containing both carboxylate and pyrazole moieties. NUS-5 is composed of porous grids stacked together into a 2D layered structure exhibiting ultra-micropores. It displays remarkable thermostability and excellent selectivity towards sorption of CO2 over N2, making it a good material candidate for post-combustion CO2 capture.

We report synthesis of an Al-based porous gel single-ion polymer electrolyte, lithium poly (glutaric acid aluminate) (LiPGAA), using glutaric acid and lithium tetramethanolatoaluminate as the precursors. The three-dimensional network compound provides short lithium-ion transport pathways and allows organic solvents to be accommodated in the composite for rapid ion transport. The tetraalkoxyaluminate units in the material enable Li-ions to be weakly associated with the polymeric framework, leading to a high ionic conductivity of 1.47 × 10−4 S cm−1 at room temperature and a high Li-ion transference number of 0.8. A membrane of the polymer was prepared via a solution cast method with PVDF-HFP poly(vinylidene-fluoride-co-hexafluoropropene) followed by soaking in a solution of ethylene carbonate (EC) and propylene carbonate (PC) (v/v, 1:1). A Li-ion battery assembled with the composite membrane displays remarkable cyclability with nearly 100% coulombic efficiency over a wide temperature range.

We report a facile synthesis of a polymeric organo–magnesium complex (MTF–Mg) by reacting Mg-modified-melamine with terephthalaldehyde for room temperature hydrogen physisorption. The pre-modification of melamine allows incorporation of exposed magnesium sites into the complex. The synthesized MTF–Mg complex exhibits a moderate BET surface area up to 137 m2 g−1 and a Langmuir surface area up to 222 m2 g−1. In this complex, magnesium metal sites act as the active sites for molecular hydrogen adsorption via an electrostatic interaction. The material shows a high isosteric heat of adsorption up to 12 kJ mol−1 and a maximum excess hydrogen uptake up to 0.8 wt% at 298 K and 100 atm, comparable to the values of high surface area MOFs with exposed metals sites under similar conditions. The role of the exposed metal sites in enhancing hydrogen uptake capacity and isosteric heat of adsorption is demonstrated experimentally.

Coordinatively unsaturated iron metal sites were introduced in the tris(aminophenyl)bezene-terephthalaldehyde framework to facilitate Kubas type metal–hydrogen binding for ambient temperature hydrogen storage applications. The synthesized compound was characterized via elemental analysis (EA), infrared spectroscopy (IR), thermogravimetric analysis (TGA), nitrogen adsorption-desorption (BET) and X-ray photoelectron spectroscopy (XPS). This complex exhibits a remarkably high gravimetric capacity up to 1.2 wt% at 298 K under 100 atm despite the relatively low BET surface area of 54.6 m2/g. The observed significant isosteric heat of hydrogen adsorption with surface coverage arises from the Kubas type of bonding supported by the results of electron paramagnetic resonance (EPR). Excellent reversibility of hydrogen adsorption was demonstrated.An organo iron compound was synthesized, exhibiting a remarkably high gravimetric capacity up to 1.2wt% at 298 K under 100 atm and a relatively high adsorption enthalpy around 10 kJ/mol.

We present a first-principles study using periodic density functional theory on a water gas shift reaction on a Feoct2-tet1-terminated Fe3O4 (111) surface. We show that water can easily undergo dissociative adsorption to form OH and H adatom species on the surface. Three possible reaction mechanisms (i.e., redox mechanism, associative mechanism, and coupling mechanism) were systematically explored based on minimum energy path calculations. It was identified that the redox mechanism is the energetically most favorable pathway for the water gas shift reaction on the Feoct2-tet1-terminated Fe3O4 (111) surface. The COO* desorption was found to be the rate-limiting step with a barrier of 1.04 eV, and the OH dissociation has the second-highest activation barrier (0.81 eV). Our results are consistent with results of kinetic and isotope exchange experiments. Our studies suggest that it is necessary to develop a promoter to reduce the activation barriers of the COO* desorption and OH dissociation steps in order to improve the catalyst performance.

Two-dimensional (2D) materials are highly promising for flexible electronics, and graphene is the only well-studied transparent conductor. Herein, density functional theory has been used to explore a new transparent conducting material via adsorption of H on a 2D β-GaS sheet. This adsorption results in geometrical changes to the local structures around the H. The calculated electronic structures reveal metallic characteristics of the 2D β-GaS material upon H adsorption and a large optical band gap of 2.72 eV with a significant Burstein-Moss shift of 0.67 eV. The simulated electrical resistivity is as low as 10–4 O·cm, comparable to the benchmark for ITO thin films.

A novel protocol to generate and control porosity in polymeric structures is presented for fabrication of single ion polymer electrolyte (SIPE) membranes for lithium ion batteries. A series of SIPEs with varying ratios of aliphatic and aromatic segments was successfully synthesized and subsequently blended with PVDF-HFP to fabricate membranes of various sizes of pores. The membranes were characterized using techniques including SEM, solvent uptake capacity measurement and ionic conductivity. We demonstrate that appropriate membrane porosity enhances ionic conductivity, reduces interfacial resistance between electrodes and electrolyte and ultimately boosts performance of Li-ion batteries. The implication of the structure–performance relationship for battery design is discussed.Keywords: battery performance; energy storage; lithium-ion batteries; polymer electrolyte; porous architecture

A novel single ion conducting block copolymer electrolyte (SI-co-PE) for applications in lithium-ion batteries is presented. The block copolymer is made of alternative ethylene oxide (EO) and aromatic segments to tune the glass transition temperature (Tg), the mechanical strength and the porosity of the material for achieving high electrochemical performance of lithium-ion batteries. Upon blending with a PVDF-HFP binder via a solution cast method, a gel SI-co-PE membrane with high ionic conductivity, a wide electrochemical window and a high lithium transference number was obtained. Excellent electrochemical stability and battery performance at both room temperature and 80 °C with various charge–discharge rates were demonstrated. The study underscores the fundamental importance of polymer electrolyte microstructures in battery performance enhancement and suggests ways to improve the design of new electrolyte materials for development of better battery devices with a long cycle life.

•Dehydrogenation of perhydro-N-ethylcarbazole was studied over 4 metal catalysts.•The catalytic activity follows the order of Pd > Pt > Ru > Rh.•Tetrahydro-N-ethylcarbazole is kinetically stable over a Rh catalyst.•5.79 wt% hydrogen release was achieved within 250 min at 180 °C over Pd catalyst.•The rate-limiting step is conversion from 4H-N-ethylcarbazole to N-ethylcarbazole.N-ethylcarbazole is one of the most promising liquid organic hydrogen carriers (LOHCs) as it can be catalytically hydrogenated and dehydrogenated at relatively moderate temperatures. In the present work, we report a systematic study on dehydrogenation of perhydro-N-ethylcarbazole over several important supported noble metal catalysts to identify the optimal catalyst for temperature-controlled dehydrogenation. The reaction takes three consecutive stages with two intermediates of octahydro-N-ethylcarbazole and tetrahydro-N-ethylcarbazole. The initial catalytic activity of the selected noble metal catalysts for the dehydrogenation process was found to follow the order of Pd > Pt > Ru > Rh. 100% selectivity toward the final product of N-ethylcarbazole and fully dehydrogenation was achieved over the supported Pt and Pd catalysts. The kinetics of the three stage dehydrogenation processes over the catalysts was studied and the rate constants were derived. The results indicate that the dehydrogenation reaction rate decreases significantly with the reaction stage for all the selected noble catalysts and the conversion from tetrahydro-N-ethylcarbazole to N-ethylcarbazole was found to be the rate-limiting step of the entire reaction process.

We report full hydrogenation of N-propylcarbazole in molten state over a supported ruthenium catalyst at 120–150 °C. A remarkably fast reaction rate was achieved with the apparent activation energy of 18.4 kJ mol−1. Two stereoisomers of the final product were identified and the less stable one was found to dominate the product distribution at lower temperatures and/or with shorter reaction times, which is highly beneficial for hydrogen release upon dehydrogenation with better purity and for enhancement of catalyst performance. The optimum conditions for catalytic hydrogenation of N-propylcarbazole were found to be at 120 °C for 60 minutes.

•The higher the surface coverage of sulfur the better the battery performance.•800 mAh g−1 after 1000 cycles at 2 C with capacity retention over 77%.•The sealed structure with narrow and irregular interstitials can host polysulfides.We explore the influence of coverage percentage of the sulfur electrode on the cycle performance of lithium-sulfur batteries. Four sulfur electrodes covered with composite films made of carbon (BP2000), nano-Al2O3 and polytetrafluoroethylene (PTFE) with different exposure are prepared and tested in lithium-sulfur batteries. The results display that both the capacity retention and coulombic efficiency are improved with the increase of surface coverage percentage among which the cell with the completely sealed sulfur electrode exhibits the best cycle performance. The discharge capacity of the sealed sulfur electrode is ca. 800 mAh g−1 after 1000 cycles at 2 C with capacity retention over 77%. The ex-situ field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Ultraviolet–Visible spectroscopy (UV) and nitrogen sorption measurements reveal that the sealed structure with narrow and irregular interstitials effectively suppresses the diffusion of soluble polysulfides out of the embraced environment with virtually no effect on lithium ion conduction. The present study demonstrates the effectiveness of the sealed structure for achieving robust electrochemical performance of lithium-sulfur batteries.Download high-res image (317KB)Download full-size image

Hydrogenation of unsaturated organosulfur compounds is an essential process through which these species are converted into cleaner and more useful compounds. Hydrogen bronze materials have been demonstrated to be efficient catalysts in hydrogenation of simple unsaturated compounds. Herein, we performed density functional theory calculations to investigate hydrogenation of thiophene on hydrogen tungsten bronze. Various reaction pathways were investigated and the most favourable routes were identified. Our results suggest that the reaction proceeds with moderate barriers, and formation of tetrahydrothiophene is facile both thermochemically and kinetically. The present study provides a useful insight into the design of hydrogenation thiophene and its derivatives and effective hydrodesulfurization catalysts.

Many applications of Sn-doped indium oxide (ITO) films in organic electronics require appropriate surface modifications of ITO nanocrystals with small organic molecules, such as silanes, phosophonic acids and carboxylic acids, to improve interfacial contacts and charge transfer. Here, we propose a new surface modification strategy via adsorption of acetylene molecules on an oxygen-terminated ITO(100) surface using a slab crystalline model to represent the nanocrystal surface. The adsorption was first studied using density functional theory. It was found that the chemisorption of C2H2 on two types of surface oxygen dimers is highly exothermic with the calculated adsorption energies of 3.80 eV and 5.19 eV, respectively. Electron population analysis reveals the origin of the strong interaction between the adsorbate and the ITO(100) surface. Experimental studies on the synthesized ITO nanocrystals using X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy confirm the predicted strong adsorption of C2H2 on ITO surfaces.

We report a polysiloxane based single-ion conducting polymer electrolyte (SIPE) synthesized via a hydrosilylation technique. Styrenesulfonyl(phenylsulfonyl)imide groups were grafted on highly flexible polysiloxane chains followed by lithiation. The highly delocalized anionic charges in the grafted moiety give rise to weak association with lithium ions in the polymer matrix, resulting in a lithium ion transference number close to unity (0.89) and remarkably high ionic conductivity (7.2 × 10−4 S cm−1) at room temperature. The high flexibility arising from polysiloxane enables the glass transition temperature (Tg) to be below room temperature. The electrolyte membrane displays high thermal stability and a strong mechanical strength. A coin cell assembled with the membrane comprised of the electrolyte and poly(vinylidene-fluoride-co-hexafluoropropene) (PVDF-HFP) performs remarkably well over a wide range of temperatures with high charge–discharge rates.

Cationic transference number and ionic conductivity of an electrolyte are among the key parameters that regulate battery performance. In the present work, we introduce a novel concept of using porous organic frameworks as a single ion-conducting electrolyte for lithium ion batteries. The synthesized lithium functionalized melamine–terephthalaldehyde framework (MTF–Li), a three dimensional porous organo–lithium complex, in a medium of organic solvent exhibits ionic conductivity comparable to the values of typical gel polymer electrolytes, and the battery cell assembled with the membrane of the material performs at both room temperature and at 80 °C. The rigid three-dimensional framework, functioning as the anionic part of the electrolyte, reduces the anionic transference number to a minimum. As a consequence, the cationic transference number increases to 0.88, close to unity. In addition, by virtue of its synthesis procedure, the electrolyte displays excellent sustainability at high temperatures, which is important for battery safety as well as for enhancing the performance and longevity of the battery.

A hyperbranched conjugated Schiff base polymer network was synthesized by condensation between 4,4′,4′′-nitrilotribenzaldehyde and p-phenylenediamine. The material exhibits excellent rate capability and long cycle life for lithium storage. Coupled with lower electrode potential (0.7 V vs. Li+/Li), it may be well suited for fully flexible thin film polymeric batteries as the negative electrode.

We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.