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Urea electrolysis is a promising approach to produce hydrogen while simultaneously purifying urea-rich wastewater. In practice, it is highly desirable but still challenging, through the structure construction strategy, to implement a method with controllable synthesis of ultra-thin nanosheet arrays with rich interfaces, and then apply them into the catalysis operations of hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). In this work, the bifunctional electrocatalyst Ni2P/NiCoP nanosheets anchored nickel foam (NF) were prepared with ultra-thin rich interfaces by regulating the Co– and P-doping. The results showed that the elaborated Ni2P/NiCoP/NF electrode delivered the excellent electrocatalytic activities for both UOR and HER operations. Particularly for UOR, it required only a cell voltage of 1.41 V at 100 mA cm−2, which was 400 mV lower than that in the traditional overall water splitting operation.

In this work, NiFe LDH/Ti3C2Tx/Nickel foam (NF) was successfully prepared as a binder-free electrode by depositing NiFe layered double hydroxide (LDH) nanosheets on Ti3C2Tx/NF substrate through electrodeposition approach. The strong electrostatic interactions between the negatively charged surface of MXene and positively charged NF substrate enabled the direct growth of NiFe LDH nanosheets on Ti3C2Tx/NF substrate. As a result, the as-prepared NiFe LDH/Ti3C2Tx/NF electrode exhibited an excellent OER performance, fast catalytic reaction kinetics and good chemical stability. Its overpotential reached 200 mV at a current density of 10 mA cm−2, and the cycling tests suggested a good cycling stability.

An outstanding oxygen reduction reaction (ORR) electrocatalyst is firstly developed deriving from sustainable rice husk (RH) biomass. Benefiting from self-doped Si in RH, the higher proportion of pyridine N, graphite N and expecially Fe-Nx as well as thiophene S contents were produced in Si-Fe/S/N-RH3 in comparison with those of Si-free Fe/S/N-RH3. Consequently, the half-wave potential of 0.89 V and the onset potential of 0.96 V are achieved for Si-Fe/S/N-RH3, outperforming the benchmark electrocatalyst Pt/C and other Fe-based electrocatalysts reported in alkaline media. Furthermore, it is found that the exisentence of self-doped Si can improve the graphitization degree of the catalyst, leading to the long-term stability (larger than 85% retention after 40000 s) and prominent methanol tolerance for Si-Fe/S/N-RH3. In addition, Si-Fe/S/N-RH3 shows a power density of 86.2 mW cm−2 and excellent durability in Zn-air battery. The work highlights the potential to develop sustainable and cost-effective ORR electrocatalysts from waste biomass as the substitute for precious metal catalysts.

Molybdenum disulfide (MoS2), a two-dimensional (2D) material, promises better desalination efficiency, benefiting from the small diffusion length. While the monolayer nanoporous MoS2 membrane has great potential in the reverse osmosis (RO) desalination membrane, multilayer MoS2 membranes are more feasible to synthesize and economical than the monolayer MoS2 membrane. Building on the monolayer MoS2 membrane knowledge, the effects of the multilayer MoS2 membrane in water desalination were explored, and the results showed that increasing the pore size from 3 to 6 A resulted in higher permeability but with lower salt rejection. The salt rejection increases from 85% in a monolayer MoS2 membrane to about 98% in a trilayer MoS2 membrane. When averaged over all three types of membranes studied, the ions rejection follows the trend of trilayer > bilayer > monolayer. Besides, a narrow layer separation was found to play an important role in the successful rejection of salt ions in bilayer and trilayer membranes. This study aims to provide a collective understanding of this high permiselective MoS2 membrane's realization for water desalination, and the findings showed that the water permeability of the MoS2 monolayer membrane was in the order of magnitude greater than that of the conventional RO membrane and the nanoporous MoS2 membrane can have an important place in the purification of water.

The P-based electrode electrocatalysts have exhibited high activities for the hydrogen evolution reaction (HER), but their structural stabilities in the long-term operation of water electrolysis pose a technical challenge for industrial-scale applications. In this study, amorphous NiP sheet arrays with rich active sites were created on nickel foam (NF) by in situ phase reconstruction, and then NiO ultrafine particles were generated within the NiP sheets. The array electrode exhibited not only enhanced catalytic activity verified by 76 mV of HER for NiO@NiP/NF at 10 mA cm-2, but also excellent structural stability in 1 M KOH solution proved by the fact that the structure of the assembled electrode remained intact after long-term operation at 100 mA cm-2 for 120 h.

In this work, the micro-controlling of the grain boundaries in NiCo2O4/NiCo2S4 nanowire arrays was achieved by exposing them to a sulfur containing atmosphere at 300 °C with different exposure times. The results showed that the capacitance of the optimal NiCo2S4 sample reached 400 μA h cm−2 at 30 mA cm−2 with a current retention rate of 58.6%. The assembled NiCo2O4/NiCo2S4//activate carbon electrode delivered a capacitance of 299.2 μA h cm−2 and 241.7 μA h cm−2 at a current density of 3 mA cm−2 and 30 mA cm−2, respectively. The cycling tests showed a good current retention rate of 88.1% after 8000 cycles. Besides, the NiCo2O4/NiCo2S4 composite exhibited a power density of 480.1 W kg−1 at an energy density of 47.87 W h kg−1, and 4773.66 W kg−1 at 38.67 W h kg−1, which indicated its potential for practical applications.

Despite the extensive studies done on the remarkable characteristics of metal–organic frameworks (MOFs) for gas storage applications, several issues still preclude their widespread commercial lightweight applications. In most cases, MOF materials are produced in powdery form and often require shaping to attain application-specific properties. Fabrication of MOF-polymer composites is considered an attractive approach for shaping MOF powders. In most cases, the final hybrid material retains the intrinsic adsorbing properties of the pristine MOF coupled with other interesting synergistic features which are sometimes superior to their pristine counterparts. In this regard, the use of porous polymers of intrinsic microporosity (such as PIM-1) has proved to be of interest. However, most of these polymers lack some other important properties such as conductivity, which is of paramount importance in a hydrogen storage system. It is on this basis that our study aimed at direct anchoring of a PIM-1/MOF viscous solution onto a carbon foam (CF) substrate. The effects of PIM-1/UiO-66(Zr) inclusion into CF to the resulting thermal properties (thermal conductivity, thermal diffusivity and volumetric heat capacity) as well as hydrogen uptake capacity was investigated. Contrary to our expectations, the incorporation of PIM-1/UiO-66(Zr) into CF only offered better handling but did not lead to the enhancement of thermal conductivity.

In our previous research, titanium-based nitride with high conductivity and superior corrosion resistance were developed as an ideal core material for replacing noble metal to form Pt-based core-shell catalysts by pulse electrodeposition. Meanwhile, the smaller sizes of nitride cores would also be available for pulse electrodeposition by dispersing them on carbon nanotubes (CNT). To achieve a better practice on the preparation of the Pt-based core-shell catalysts, in this work, both nitrogen-doped carbon nanotubes (N-CNT) and reduced graphene oxide (N-rGO) were used to support the copper-doped titanium nitride (Ti0.9Cu0.1N) cores. In the course of pulse electrodeposition, their influences as supports on the electronic states of electrodeposited Pt as well as their catalytic activities were compared. The results showed that the Pt preferred to electrodeposit on Ti0.9Cu0.1N cores supported by N-CNT and formed a core-shell structure. While with the same electrodeposition process, the Pt was found to be electrodeposited not only on the Ti0.9Cu0.1N cores supported by N-rGO with heavy aggregations but also on the N-rGO support. Raman spectroscopy analysis indicated that the higher degree of structural defects on N-rGO, as support, might have contributed to such divergence observation.

Prussian blue (PB) and its analogues have been widely investigated as promising cathode materials for potassium ion batteries (PIBs) on account of their 3D open framework, which makes the intercala...

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The bearing capacity of embankment filled by coarse-grained saline soils will be deteriorated after freeze-thaw, especially when shallow groundwater is included. Direct shear tests were carried out on coarse saline specimens that experienced freeze-thaw cycling. The shear strength of soil specimens at three densities strongly depends upon the normal stress when freeze-thaw is not involved, manifesting as a linear increase. Strength indexes such as cohesion and internal friction angle grow at higher dry densities while little change noted in the residual. The cohesion increases with salt content but lowers with freeze-thaw, especially in initial five cycles, beyond which it stabilizes. The internal friction angle is not associated with the above two factors. The stress-strain curves after freeze-thaw are all strain softening, especially at higher densities. The shear stress exhibits larger influence on particle crushing than freeze-thaw. The modified relative breakage index was calculated based on particle grading curves, and is negatively correlated with the cohesion. An empirical equation was proposed by fitting test data incorporating both salt content and freeze-thaw cycles. Comparisons prove that the calculated cohesion agrees well with the measured data.

Thermal energy storage system is of great significance for the concentrated solar power system to keep the balance between power generation and demand. Metal hydride based thermal energy storage system is regarded as a promising method due to its good reversibility, low cost, and no by-product. Multi-phase heat exchange has much higher heat transfer coefficient than single-phase fluid heat exchange, thus facilitating the steam generation. In this study, a two-dimensional model of the metal hydride reactor using multi-phase heat exchange is proposed to estimate the performance and its feasibility of application in the concentrated solar power system. The results show that the velocity of the heat transfer fluid should match well with the thermal conductivity of the metal hydride bed to maintain the heat flux at a relatively constant value. The match of thermal conductivity of 3 or 5 W/(m·K) and fluid velocity of 0.0050 m/s results in the heat flux up to about 19 kW/m2, which is increased by 3 orders of magnitude than single-phase heat exchange. In the thermal energy storage system, the reheating cycle is recommended to improve the utilization of the thermal energy. The efficiency of the system could be improved from 18.4% to 30.8% using the reheating cycle. The increased efficiency is comparable to the previously reported efficiency of 39.2%. Besides, the operation strategy of raising the steam temperature by increasing the hydrogen pressure or the superheater temperature is suggested for the system to obtain higher efficiency.

The finite element method (FEM) models of expanded polystyrene (EPS) concrete were established to study the relationships among dynamic damage, energy absorption and efficiency of buffering materials with varied flexible aggregate contents and impact speeds based on the existing split Hopkinson pressure bar (SHPB) experiments. Applied material indexes including damage degrees, crack rates and energy absorption capacities, and the dynamic responses of EPS concrete under impact loading were investigated. The results show that the failure types of these materials evolve from quasi-brittle destruction to flow-plastic destruction, the damage degree of EPS concrete increases with the enhancement of flexible aggregate content, and the peak of crack rate exists around the extreme point of shock velocities. The energy-absorption efficiency of EPS concrete increases nonlinearly when the EPS beads increase and the shock speed enhances, respectively.

Herein, we report a simple method for the preparation of cross-linked polymer of intrinsic microporosity (PIM-1)/Materials Institute Lavoisier chromium (III) terephthalate [MIL-101(Cr)] monoliths which involves direct impregnation of PIM-1 with MIL-101(Cr) powder by physical mixing in tetrachloroethane solvent. This procedure yields monoliths with high metal–organic framework (MOF) loading weight percentages of up to 80 wt% of MIL-101 powder with little loss of composite mechanical strength. From the nitrogen adsorption isotherms, it was observed that the PIM-1/80 wt% MIL-101(Cr) had good retention of MOF filler surface area and accessibility of its micropores with nearly no pore blocking effects. The hydrogen adsorption was also not far from the estimated hydrogen uptake capacity based on the MIL-101 weight percentage estimation. As a consequence of the highly porous nature of the hybrid material, PIM-1/MIL-101(Cr) composite has been considered as a promising material for inclusion in hybrid hydrogen storage cylinders. Moreover, these composites provided better handling compared to the crystalline powder MOFs without compromising the properties of MOF.

Hybrids of graphite nanosheet-supported CoMoS4 (GN-CoMoS4) were synthesized through a hydrothermal method. The CoMoS4 nanoparticles are uniformly distributed on the graphite nanosheets, leading to large specific surface area and good electrical conductivity. The GN-CoMoS4 hybrids were systematically studied for electrode materials of supercapacitors. Due to the amorphous characteristic of CoMoS4, which can supply more transportation channels for ion diffusion, together with the large specific surface area and excellent conductivity of GN, the as-prepared hybrid electrode material exhibited a high specific capacitance of 774 F g−1 at the current density of 1 A g−1 and an excellent cyclic stability (94.49% of its initial specific capacitance retained after 6000 cycles at a current density of 8 A g−1). An all-solid-state asymmetric supercapacitor was fabricated using GN-CoMoS4 as positive electrode and porous active carbon (AC) as negative electrode, which exhibited a highest energy density of 42.85 W h kg−1 at 900 W kg−1 and excellent cycling stability (93.2% retention after 8000 cycles). The results demonstrate that the GN-CoMoS4 hybrids are promising candidate for the electrode materials in high-performance supercapacitors because of the well-designed microstructure.

Tin oxide (SnO2) is widely used in perovskite solar cells (PSCs) as an electron transport layer (ETL) material. Ethanol usually serves as a solvent of ETL but no one discussed the possible influences caused by ethanol. In this work, the effects of ethanol were investigated systematically. It is clear that ethanol treatment (EtOH-SnO2) can remove surface disorder of mesoporous SnO2 and thus enhance the conductivity as well. As a result, the champion PCE of 21.62% is obtained in PSC with EtOH-SnO2 ETL, which is higher than that of control device (20.70%) due to improved film quality. Meanwhile, compared with control PSCs, the stability of the perovskite layer deposited on EtOH-SnO2 ETL is gradually improved both for the light and thermal stability. Therefore, we make clear that the ethanol treatment can improve the quality of mesoporous SnO2 and perovskite films for optoelectronic device.

Seeking to design high-efficiency catalyst (LMO@N-rGO) for Li-O2 batteries, we suggested a one-step hydrothermal strategy to grow well-crystallized spinel LiMn2O4 (LMO) nanoparticles homogeneously on nitrogen-doped reduced graphene oxide nanosheets (N-rGO). We found that the prepared material can yield a twin-function battery, functioning as a Li-O2 (air) battery under the oxygen atmosphere and a Li-ion battery in the absence of oxygen. In the Li-O2 configuration, the material displayed a lower charge plateau voltage for 0.21 V and excellent cycling performance (120 cycles at 1000 mA h g–1 limited capacity). Furthermore, in the absence of oxygen, the material exhibited very good Li-ion battery cathode performance, achieving a capacity of up 80 mA h g–1. On the basis of our characterization results, three reasons are suggested for the twin performance of the material: the highly uniform dispersion of LMO nanoparticles, the improved Li diffusion kinetics, and the synergic effect between the spinel LMO nanop...

The wettability, or hydrophobic-hydrophilic balance, of cathode catalyst layer influences the performance of the proton exchange membrane fuel cell. In this paper, cathode catalyst layer with different polytetrafluoroethylene contents are prepared, and the effect of hydrophobic-hydrophilic balance on the performance of the membrane electrode assembly is investigated intensively. It is found that wettability, or hydrophobic-hydrophilic balance, of cathode catalyst layer can significantly affect the performance of membrane electrode assembly, and it can be effectively tuned by varying the loading of polytetrafluoroethylene. With the addition of polytetrafluoroethylene, the hydrophobicity of cathode catalyst layer, reflected by the contact angel, can be changed from 135.6° of that without addition of polytetrafluoroethylene to 146.5° with 70 wt.% polytetrafluoroethylene addition, and the optimal addition amount is 50 wt.%. For our optimal membrane electrode assembly with optimal addition of polytetrafluoroethylene in cathode, its current density are recorded as 990 mA cm–2 at 0.7 V and 1400 mA cm–2 at 0.6 V, respectively; its maximum power density is up to 856 mW cm−2. Furthermore, our polytetrafluoroethylene-incorporated membrane electrode assembly also exhibits excellent stability, and current density only drops from 1000 mA cm−2 to 900 mA cm−2 after a continuous operation of 60 h.

A high-performance Ni/Mo co-doped lithium manganate composite material, LiNi0.03Mo0.01Mn1.96O4, is prepared by a solid-state method, then a biomass-derived carbon layer with ethyl cellulose as the carbon source is applied to the surface of the composite particles. We find that carbon layer with the proper loading can significantly enhance the material’s cyclic stability and capacity at high discharge rates. At rates of 5C and 10C, our optimal sample (LNMMO-3wt%C), with 3 wt% carbon layer loading, has discharge capacities up to 114 and 98 mAh g−1, respectively, which are 10 and 8% higher than those of the uncoated co-doped material. Further, the carbon layer coating significantly improves the material’s stability at high discharge rates: the capacity retention of LNMMO-3wt%C after 400 cycles at discharge rates of 5C and 10C is high reaching 93.6 and 88.1%, respectively, compared with 91.4 and 74.3% for uncoated LNMMO. Based on our experimental results and analysis, we attribute the enhanced stability and capacity at high discharge rates to two factors: (i) enhanced conductivity and (ii) reduced Mn3+ dissolution, combined with significantly decreased resistance from Li+ ion intercalation/de-intercalation, due to the uniformity of the carbon layer coating.

In this study, two waste materials namely; coal fly ash (CFA) and waste tyres pyrolysis oil, were successfuly utilized in the synthesis of carbon nanofibers/tubes (CNF/Ts). In addition, Fe-rich CFA magnetic fraction (Mag-CFA) and ethylene gas were also used for comparison purposes. The carbons obtained from CFA were found to be anchored on the surface of the cenosphere and consisted of both CNTs and CNFs, whereas those obtained from Mag-CFA consisted of only multi-walled carbon nanotubes (MWCNTs). The study further showed that the type of carbon precursor and support material played an important role in determining the nanocarbon growth mechanism. The findings from this research have demonstrated that it is possible to utilize waste tyres pyrolysis oil vapor as a substitute for some expensive commercial carbonaceous gases.

In this study, we investigated the potential for use of waste tyre pyrolysis oil vapour as a carbon precursor in the synthesis of zeolite templated carbons (ZTC). With Zeolite 13X as the template, the ZTCs were synthesised using two methods namely: 1-step process which involved the carbonization of gaseous carbon precursor in the zeolite template (in this case, ethylene and pyrolysis oil vapour) and the 2-step synthesis method involved the impregnation of zeolite pores with furfural alcohol prior to carbonization of the gaseous carbon precursor. The replication of the zeolite 13X structural ordering was successful using both methods. The 2-step synthesized ZTCs were found to possess the highest specific surface area (3341 m2 g-1) and also had the highest H2 storage capacity (2.5 wt.%). The study therefore confirmed an additional novel strategy for value-addition of waste tyre pyrolysis by-products.

The performance evaluation on water splitting electrodes is usually conducted in laboratory at current density range of 10–100 mA cm−2, and this is far from satisfactory for the industrial practices that require the operating current density larger than 400 mA cm−2. In this work, an efficient hybrid electrode is developed by firstly electro-etching the nickel mesh (E-NM) in actual seawater and then in-situ depositing nickel nanowires (NWs) onto E-NM substrate under the externally applied magnetic field. The results show that NWs are integrated into the defective E-NM structure. The assembled NWs/E-NM hybrid electrode achieves a high current density of 800 mA cm−2 at 2.0–2.1 V, which outperforms the commercial NM electrode. Moreover, the current density does not decay after 100 h stability test at 500 mA cm−2.

The comparable catalytic activities of non-noble metal electrocatalysts are the prime to enable their breakthrough performances for oxygen reduction reaction (ORR). In this work, the nitrogen-doped carbon aerogels are strategically functionalized with Ce/Fe elements. The increased content of pyridinic nitrogen from 16.71% to 20.28% coupled with a macro-porous structure result in an enhanced ORR catalytic performance. The performance evaluation shows that the ORR onset potential of the functionalized sample shifts from 0.893 V to 0.968 V comparing to the unfunctionalized sample. The open cell voltage reaches 1.450 V when the optimal catalyst is assembled into a zinc-air cell as the cathode, and such performance is comparable to the commercial Pt/C catalyst.

Loop heat pipe has a wide application in the fields of airborne electronics cooling and thermal management. However, the pertinent temperature oscillation of the loop heat pipe could lead to adverse effects on the electronics. In the current study, an ammonia-stainless steel dual compensation chamber loop heat pipe was developed to experimentally investigate the temperature oscillation under different acceleration conditions. The impact of several control parameters such as different heat loads, loading modes, acceleration directions and magnitudes on the operational performance of the loop heat pipe was analyzed in a systematic manner. The heat load applied on the evaporator ranged from 25 W to 300 W. The acceleration magnitude varied from 1 g to 9 g and four different acceleration direction, i.e. configurations A, B, C and D, were taken into account. Two different loading modes were applied with different heat load and acceleration force. Experimental results show that (i) the loop temperature will change and oscillate as the acceleration force was applied under all test conditions. It can be easily found that the temperature oscillation occurred at both heat loads of 250 W and 300 W. (ii) for the case of the first loading mode, periodic temperature oscillation is observed on the liquid line, whereas for the second loading mode, periodic temperature oscillation can be easily appeared on the entire loop. (iii) the loop temperature under both configurations A and B with acceleration of 7 g does not oscillate at heat load of 150 W, 200 W and 250 W when the first loading mode is applied. Especially under configuration B, the acceleration could contribute to repress the temperature oscillation. Under the current heat loads for almost all cases, the temperature oscillation can be observed for configurations A, C and D with acceleration of 5 g. (iv) the amplitude of evaporator at heat load of 300 W under configuration C are 0.6 °C, 0.3 °C, 0.2 °C and 0.3 °C with acceleration of 3 g, 5 g, 7 g and 9 g. The corresponding period is 66 s, 36 s, 34 s and 36 s, respectively.

The fabrication of application-specific metal-organic framework (MOF) composites has the potential to shift more towards hydrogen storage system integration. The in-situ growth of nano particles on a graphene surface is a common technique for synthesizing graphene-inorganic nanocomposites and in this study, a graphene foam (GF) / zirconium-based MOF (UiO-66) composite was prepared using a two-step solvothermal method. Brunauer, Emmett and Teller (BET) surface area as well as hydrogen uptake capacity were measured under cryogenic conditions and compared to the values for pristine UiO-66. The GF/UiO-66 composite had a BET surface area of 1073 m2.g-1 and a hydrogen uptake capacity of 1.1 wt% at 77 K and 1.2 bar pressure, compared to 1367 m2.g-1 and 1.5 wt%, respectively for pristine UiO-66 under the same conditions. Besides the values being compromised relative to pristine UiO-66, the two-step in-situ synthesis approach yielded a composite with enhanced BET surface area and H2 uptake relative to a composite obtained from a single step synthesis approach. The composites further exhibited better thermal stability than the pristine UiO-66 and show promise for the development of powdered MOF materials towards hydrogen storage system integration.

We report a rare case whereby a metal–organic framework (MOF), namely UiO-66, is compacted at high pressure (∼700 MPa or 100 000 psi) resulting in densification and improved total volumetric hydrogen storage capacity, but crucially, without compromising the total gravimetric uptake attained in the powdered form of the MOF. The applied compaction pressure is also unprecedented for MOFs as most studies have shown the MOF structure to collapse when compacted at very high pressure. The UiO-66 prepared in this study retained ∼98% of the original surface area and microporosity after compaction at ∼700 MPa, and the densified pellets achieved a total H2 uptake of 5.1 wt% at 100 bar and 77 K compared to 5.0 wt% for the UiO-66 powder. Depending on the method used to compute the volumetric uptake, the densified UiO-66 attained unprecedented volumetric capacity at 77 K and 100 bar of up to 74 g L−1 (13 g L−1 at 298 K) compared to 29 g L−1 for the powder (6 g L−1 at 298 K) using a conventional method that takes into account the packing density of the adsorbents, or 43 g L−1 (compared to 35 g L−1 for the powder at 77 K and 100 bar) based on a method that uses both the single crystal and skeletal densities of MOFs. However, regardless of the difference in the calculated values according to the two methods, the concept of UiO-66 compaction for improving volumetric capacity without compromising gravimetric uptake is clearly proven in this study and shows promise for the achievement of hydrogen storage targets for a single material as set by the United States Department of Energy (DOE).

The cycling stability of Li–O2 batteries has been impeded by the lack of high-efficiency, and durable oxygen cathodes for the oxygen-reduction reaction (ORR) and the oxygen-evolution reaction (OER). Herein we report a novel TiN nanorod array-based cathode, which was firstly prepared by growing a TiN nanorod array on carbon paper (CP), and then followed by depositing MnO2 ultrathin sheets or Ir nanoparticles on the TiN nanorods to form well-ordered, three-dimensional (3D), and free-standing structured cathodes: TiN@MnO2/CP and TiN@Ir/CP. Both cathodes exhibited good specific capacity and excellent cycling stability. Their specific discharge capacities were up to 2637 and 2530 mA h g−1, respectively. After 200 cycles for 2000 h at a current density of 100 mA g−1, no obvious decays were observed for TiN@MnO2/CP and TiN@Ir/CP cathodes, while significant decreases were observed after the 80th and 30th cycles for the Pt/C and TiN/CP cathodes, respectively. Such high performance can be ascribed to the 3D array structure with enough microspace and high surface area, which facilitated the high dispersion of active components and prevented the formation of large/irreversible Li2O2.

The increase in waste tyres has led scientist in the quest for finding various ways for minimizing problems associated with their disposal. The sought solutions are not only meant to be environmentally friendly but also be able to boost the economy. Pyrolysis of waste tyres is one of the preferred ways of recycling waste tyres since it gives valuable products such as pyrolysis oil, gas and solid char. Solid char has low surface area and contains inorganic traces that disadvantage it from competing with commercial carbon black. The aim of this study was to apply the mechanochemical approach, which is the compaction of the solid char with an activating agent before the activation process in order to increase reactive sites. The solid char was initially treated with water, HF and HNO 3 prior to the mechanochemical approach. The obtained materials were analysed using EDS, XRD and FTIR. The textural properties were also studied using N 2 sorption isotherms. The HNO 3 washed and compactivated CB had the highest surface area of 955.20 m 2 /g and also the highest H 2 storage capacity of 1.4 wt.% at 1 bar.

High-performance ferric phosphate (FePO4), with well-defined ellipsoid morphology and uniform particle size distribution, is successfully fabricated via a green spray drying method with formic acid as additive. It is found that the added formic acid plays a crucial role for the formation of the well-distributed FePO4 particles. Benefited by the outstanding structure and properties of ferric phosphate prepared above, a high performance of lithium iron phosphate (LiFePO4) has been prepared. It exhibits high capacity, especially at high charging/discharging rate (158.4 mAh g−1 at 0.2 C and 107.3 mAh g−1 at 10 C), and excellent cycling stability (without capacity fading after cycling for 200cycles at 1 C). All these impressive electrochemical performance could be ascribed to the FePO4 precursor, and further attributed to the addition of formic acid, which may play as a template, resulting in the well-defined morphology, uniform particles size distribution, hierarchical pore structure, and high surface area of the ferric phosphate.

The performance of the proton exchange membrane fuel cell (PEMFC) is significantly improved through introducing nitrogen-doped carbon nanotubes (NCNTs) into the catalyst layer (CL) and microporous layer (MPL) of the membrane electrode assembly (MEA), it reveals by SEM images that the NCNTs are uniformly dispersed in CL and MPL, resulting in the more plenty of porosity, higher surface area, better conductivity, and better prevention of the layer cracks. The BET surface area and pore volume of MPL are increased by 88% and 77% respectively with the addition of 20 wt% of NCNTs in MPL. The membrane electrode assembly (MEA) with adding 20 wt% NCNTs both in cathode CL and in cathode GDL can yield the best cell performance. At a cell temperature of 70 °C and 30 psi back pressures, the current density is up to 1000 mA cm−2 at 0.7 V and 1600 mA cm−2 at 0.6 V, and the max power density reaches 997 mW cm−2.

A composite material consisting of Zr-based metal organic framework (Zr-MOF) and reduced graphene oxide (rGO) was successfully synthesized by an in situ method. The aim of the study was to transfer some of the graphene's attractive properties to the MOF materials. An important observation was that the incorporation of rGO did not alter or interfere with the crystallization of the MOF material. The studies showed an increase in surface area for the rGO/Zr-MOF composite (1480 m2/g) when compared to that of pristine Zr-MOF (1116 m2/g). There was also an enhancement of the hydrogen storage capacity from 1.4 wt% to 1.8 wt% for the GO/Zr-MOF composite. This enhancement could be attributed to the synergistic contribution of interactions of rGO sheets with hydrogen as well as from the possible expansion of the pore space in the Zr-MOF induced by the presence of the graphene-like material.

In this study, a novel low-Pt core-shell catalyst is successfully prepared by depositing ultrathin Pt layer on the carbon nanotubes supported titanium nitride nanoparticles (TiN@Pt/CNTs) via a facile pulse electrochemical deposition approach. The catalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), High-angle annular dark field (HAADF) and energy-dispersive spectrometer (EDS) elemental mapping, X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The results confirm the core-shell structure of the prepared TiN@Pt/CNTs catalyst. More importantly, the catalyst exhibits superb mass activity and durability for the methanol oxidation reaction (MOR) than that of the commercial JM Pt/C catalyst. Later experiments data demonstrate that the activity and stability of the catalyst can be further enhanced via copper doping, which results from the modified electronic structure of the Pt atoms and the synergistic effects of the core-shell structure.

Porous materials such as metal organic frameworks (MOFs), zeolite templated carbons (ZTC), and some porous polymers have endeared the research community for their attractiveness for hydrogen (H2) storage applications. This is due to their remarkable properties, which among others include high surface areas, high porosity, tunability, high thermal, and chemical stability. However, despite their extraordinary properties, their lack of processability due to their inherent powdery nature presents a constraining factor for their full potential for applications in hydrogen storage systems. Additionally, the poor thermal conductivity in some of these materials also contributes to the limitations for their use in this type of application. Therefore, there is a need to develop strategies for producing functional porous composites that are easy-to-handle and with enhanced heat transfer properties while still retaining their high hydrogen adsorption capacities. Herein, we present a simple shaping approach for ZTCs and their MOFs composite using a polymer of intrinsic microporosity (PIM-1). The intrinsic characteristics of the individual porous materials are transferred to the resulting composites leading to improved processability without adversely altering their porous nature. The surface area and hydrogen uptake capacity for the obtained shaped composites were found to be within the range of 1,054–2,433 m2g−1 and 1.22–1.87 H2 wt. %, respectively at 1 bar and 77 K. In summary, the synergistic performance of the obtained materials is comparative to their powder counterparts with additional complementing properties.

Pallet is a very important innovation in logistics industry. Pallets are so widely used that we can find them in nearly every logistical operation scenario. In order to manage pallets efficiently, researchers have developed several pallet management strategies (PMS). The most common and widely accepted PMS includes extensive management of pallets (EMP), transfer of pallet’s ownership (TPO), and pallet rent (PR). This paper addresses mainly on how to help pallet managers choose a certain kind of PMS from the perspective of supply chain cost. Firstly, cost models of three kinds of PMS are presented. Secondly, all parameters involved in the models are valued based on data that is collected from industry survey. The results show that the cost of PR is constantly lower than EMP, and also lower than TPO when the operation period is no more than 37 months. Finally, the effect of several important parameters on the cost is studied by sensitivity analysis. The selection strategies of PMS are proposed based on the results.

The current study explored the application of the electrospinning technique to produce multi-hierarchical composites for hydrogen storage applications. Predetermined control of fibre porosity is expected to enable production of well-defined hierarchical pore structure. The study involved encapsulation of highly porous zeolite-templated carbon (ZTC) into electrospun fibres and testing of the resulting composites for hydrogen storage. The hydrogen storage capacity of the composite fibres was 1.83%, compared with 2.39 wt% for powder ZTC material. The potential of the electrospinning technique as a shaping option for preparing composites from loose powder is demonstrated. The ZTC–polyacrylonitrile (ZTC-PAN) composite retained about 76% of the hydrogen storage capacity of the ZTC. Vacuum degassing of the ZTC–PAN electrospun composite was also found to enhance the development of porosity, aiding hydrogen penetration into zeolite pores.

Metal-organic frameworks (MOFs) have been considered with various novel applications and the development of cost-effective processes is essential for further practices. In this work, waste PET bottles were demonstrated as the source of acid linker to prepare value-added metal-organic frameworks UiO-66(Zr), and the texture properties as well as hydrogen storage capacity are comparable to those derived from commercial chemicals. This process offers an economically attractive strategy for eliminating waste PET stream while making value-added materials.

In this study, nanostructured graphite (nano-G) was added to LiBH4 and examined with respect to its effect on the hydrogen storage properties of the system. Our study found that nano-G is an effective additive for promoting the reversible dehydrogenation of the LiBH4. A series of control experiments were carried out to optimize the sample preparation method, milling time and addition amount of nano-G. In comparison with the pure LiBH4, the LiBH4/nano-G composite prepared under optimized conditions exhibits enhanced dehydrogenation kinetics and improved cyclic stability. Particularly, after addition of LiH to the LiBH4/nano-G composite, the reversibility was further improved. A combination of phase/chemical state analyses has been conducted to gain insight into the promoting effect of nano-G on the reversible dehydrogenation of the LiBH4. Our study found that nano-G exerts its promoting effect via interaction with LiBH4 and as grinding aid.

It is of great economic value to produce high-value PET-based MOF materials by the veritable elimination of waste PET, and provide sufficient MOF materials for hydrogen storage applications. Consequently, this work demonstrates the use of waste PET bottles as direct source of BDC acid linker during the synthesis of Cr-MOF. The PET-derived Cr-MOF materials showed even better textural and hydrogen storage properties than that from commercial BDC (Sigma–Aldrich).

A novel self-humidifying membrane electrode assembly (MEA) with homemade multi-functional Pt/SnO 2 –SiO 2 /C as the anode was developed to improve the performance of a proton exchange membrane fuel cell under low humidity. The MEAs' performance was evaluated at various temperatures and relative humidity levels. One MEA with a Pt/SnO 2 –SiO 2 /C anode catalyst achieved excellent low-humidity performance at a cell temperature of up to 60 °C: the current density reached 600 mA cm −2 at 0.7 V and 1050 mA cm −2 at 0.6 V with 10% RH; after 96 h of continuous operation under the same conditions, the current density decreased by only 16% (to ∼880 mA cm −2 ), whereas the current density of an MEA with JM Pt/C as the anode degraded by more than 60% within 10 h. The contact angle of the Pt/SnO 2 –SiO 2 /C anode was much lower than that of the Pt/C anode, indicating the former's excellent wettability. The high performance of the MEA with the Pt/SnO 2 –SiO 2 /C anode is attributable to the wettability of the doped binary oxide, especially of silicon oxide, and the promotion of tin oxide, which caused an interaction between the Pt and the oxide, resulting in enhanced performance under low humidification.

N-doped carbon-encapsulated transition metal selenides (TMSs) have garnered increasing attention as promising electrocatalysts for hydrogen evolution reaction (HER). Accurately regulating the electronic structure of these nanohybrids to reveal the underlying mechanism for enhanced HER performances is still challenging and thus requires deep excavation. Herein, a series of pomegranate-like Nix Sey @NC core-shell nanohybrids (including Ni0.85 Se @ NC, NiSe2 @NC, and NiSe@NC) through controllable selenization of a Ni-MOF precursor is reported. The component of the nanohybrids can be fine-tuned by tailoring the selenization temperature and feed ratio, through which the electronic structure can be synchronously regulated. Among these nanohybrids, the Ni0.85 Se @ NC exhibits the optimum pH-universal HER performance with overpotentials of 131, 135, and 183 mV in 0.5 m H2 SO4 , 1.0 m KOH, and 1.0 m PBS, respectively, at 10 mA cm-2 , which are attributed to the increased partial density of state at the Fermi level and effective van der Waals interactions between Ni0.85 Se and NC matrix explained by density functional theory calculations.

Metal–organic frameworks (MOFs) hybrid composites have recently attracted considerable attention in hydrogen storage applications. In this study a hybrid composite of zeolite templated carbon (ZTC) and Cr-based MOF (MIL-101) was synthesised by adding the templated carbon in situ during the synthesis of MIL-101(Cr). The obtained sample was fully characterized and hydrogen adsorption measurements performed at 77 K up to 1 bar. The results showed that the surface areas and the hydrogen uptake capacities of individual MIL-101 (2552 m2 g−1, 1.91 wt%) and zeolite templated carbon (2577 m2 g−1, 2.39 wt%) could be enhanced when a hybrid MIL-101(Cr)/ZTC composite (2957 m2 g−1, 2.55 wt%) was synthesized. The procedure presents a simple way for enhancement of hydrogen uptake capacity of the individual Cr-MOF and templated carbon samples.

Nanoporous carbons which possess high surface areas and narrow pore size distributions have become one of the most important classes of porous materials with potential to be utilized for hydrogen storage. In recent times, several metal–organic frameworks (MOFs) have been shown to be promising precursors for creating nanoporous carbons due to their high surface areas and tunable pore sizes. The pore structure and surface area of the resultant carbon materials can be tuned simply by changing the calcination temperature. In this work, a zinc-based MOF (MOF-5) and a chromium-based MOF (Cr-MOF) were both used as precursors for syntheses of nanoporous carbons by the direct carbonization technique at different temperatures. The resultant carbon nanostructure from MOF-5 possessed higher surface area, higher pore volume and enhanced hydrogen storage capacity as compared to pristine MOF. Meanwhile, the derived carbons from Cr-MOF displayed lower surface areas, pore volumes and hydrogen uptake than the parent MOF due to the formation of chromium oxide and carbide species in the pores of the Cr-MOF-derived carbons.

Metal–organic framework (MOF) materials are only obtained as loose powders with low packing density and thermal conductivity. To enable the developed MOF powdered materials to be utilized in a hydrogen storage system, in this study, MIL-101 nanocrystals, as an example, were prepared and immobilized on Ni foam as multi-layers. The hydrogen storage properties of individual and hybrid materials were assessed and compared. The hybrid material with 81 wt.% loading of MIL-101(Cr) nanocrystals exhibited a hydrogen adsorption capacity of 1.5 wt.% at 77 K and pressure up to 1 bar. Although the value is compromised relative to that of pure MIL-101(Cr) powder (1.9 wt.%), this approach facilitates the transition of developed MOFs powdered materials from laboratory toward system integration.

This paper presents comparative results of structural, morphological and hydrogen sorption properties between commercial and fly ash-derived zeolite X including their respective templated carbon derivatives. The surface area of commercial zeolite was found to increase by 328% from 796 m2 g−1 to 2578 m2 g−1 upon templation process whereas that of fly ash-derived zeolite increased by 275% from 404 m2 g−1 to 1112 m2 g−1 on templation. The trend in hydrogen uptake was also proportionally mirrored by the surface area. Commercial analysis estimated that the cost of synthesizing zeolite X from fly ash is one fifth that of the existing commercial zeolite production process. The use of fly ash-derived zeolites is expected to present a cost effective and competitive way of producing zeolite templated carbons. Additionally, fly ash zeolitization together with its use in the synthesis of templated carbons also present an attractive way of beneficiating coal fly ash.

In this work, we synthesized Zr-fumarate MOFs by applying water as solvent and formic acid as modulator. Highly crystalline Zr-fumarate MOF obtained from 120 °C, 24 h synthesis conditions showed high thermal and hydro stabilities. Compared to the early reported MOF materials, the lower cost, more environmentally friendly synthesis process and comparable hydrogen uptake capacity make Zr-fumarate MOFs a good candidate for hydrogen storage applications.

In this study, Zr-MOF and Cr-MOF were chosen as representatives of the developed MOFs in our laboratory and were incorporated into electrospun nanofibers. The obtained MOF nanofibers composites were evaluated as hydrogen storage media. The results showed that the incorporation of vacuum degassing was able to create visible porosity in and/or on the PAN nanofibers and the MOF nanocrystals inside the polymeric nanofibers were fully accessible by N 2 and H 2 gases. With 20 wt.% loading of MOF nanocrystals, the composites were able to achieve over 50% of the H 2 uptake capacity of individual MOF nanocrystals. In addition, the composites also showed good thermal stabilities.

In this work, the existence of structural defects in core-shell MIL-101(Cr)@UiO-66(Zr) and pure UiO-66(Zr) wereproposed. It was found that longer synthesis time leads to larger crystals, which are however not perfect as they morphologically appear to be. During the synthesis, the 1,4-benzenedicarboxylic acid (BDC) linker and modulator (HCOOH) may play competitive roles. The modulator employed does not only modulate the crystal growth, but also contributes in the formation of the MOF framework and promotes defects. Although structural defects would facilitate hydrogen storage in MOF structures, they need to be tuned to an optimum level for hydrogen adsorption purpose.