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CeOHCO3 hierarchical structures with tunable size and defects were synthesized via a simple and rapid microwave-assisted hydrothermal approach for ultra-wide band microwave absorption for the first time.

In order to solve the oxidation problem of the Ni-based solid oxide electrolysis cells (SOECs), SOECs with symmetrical electrode Sm0.5Sr0.5FeO3-δ- Gd0.1Ce0.9O2-δ (SSF-GDC) were systematically investigated, including the steam partial pressure, the working temperature, the electrolysis voltage. The reversible symmetrical cells with SSF-GDC electrode under humidified hydrogen presented good reversibility, and the maximum electrolysis current density was 1025 mA cm−2 at 800 °C with the applied voltage of 2V. In the case of direct N2 with 20% steam partial pressure as fuel, the symmetrical cells generated the maximum electrolysis current density increased from 267 to 1560 mA cm−2 at 650–800 °C. The influence of the steam partial pressure on the steam electrolysis showed that the maximum electrolysis current densities increased with the increase of the steam partial pressure from 3% to 20%, and the steam electrolysis with 3% steam partial pressure showed obvious concentration polarization due to insufficient steam partial pressure at high electrolysis current density. Finally, the short-term stability at different electrolysis voltages and long-term stability at the electrolysis voltage of 1.5V showed that there was no attenuation after 25 h operation, indicating that SSF-based symmetrical electrodes cab be an alternative to Ni-based fuel electrode materials for high-temperature steam electrolysis.

To solve the severe electromagnetic (EM) radiation from the widespread application of electronic equipment, we developed a simple template-guided oxypolymerization strategy to synthesize polypyrrole (PPy) planar helixes as an efficient EM wave (EMW) absorber, and systematically investigated the morphology-dependent chirality, conductivity, and microwave absorption properties. As HCl concentration [HCl] varied from 0 to 2.0 M, the morphology evolved from planar helix to 3D cross-linking network structures, the conductivity increased from 0.0019 to 0.0302 S/cm, and the EM parameters peaked at [HCl]=0.5 M. Compared to other absorbers, the PPy planar helix formed at [HCl]=0 M possessed wider absorption band (5.84 GHz), smaller matching thickness (1.6 mm), lower loading (25 wt.%), and intenser absorption (−48.17 dB). The reason lies in the strong attenuation capability, multiple resonances, multiple scattering, and good impedance matching generated by chiral PPy planar helixes with a distinctive helical configuration, doped heteroatoms (O,S), and a local conductive network. Our results suggest that PPy planar helixes offer great promise for fields such as chiral sensors, electronics, optics, chiral catalysis, and EMW absorption and shielding due to their distinctive morphology, tunable conductivity, and outstanding EMW absorption properties (EMWAPs).

The preferential capture of ethane (C2H6) over ethylene (C2H4) presents a very cost-effective and energy-saving means applied to adsorptive separation and purification of C2H4 with a high product purity, which is however challenged by low selectivity originating from their similar molecular sizes and physical properties. Substituent engineering has been widely employed for selectivity regulation and improvement, but its effect on C2H6/C2H4 separation has been rarely explored to date. In this work, four isoreticular coordination framework compounds based on 5-(pyridin-3-yl)isophthalate ligands bearing different substituents were rationally constructed. As revealed by isotherm measurements, thermodynamic studies, and IAST computations, they exhibited promising utility for C2H6/C2H4 separation with moderate adsorption heat and a high uptake amount at a relatively low-pressure domain. Furthermore, the C2H6/C2H4 separation potential can be finely tuned and optimized via purposeful substituent alteration. Most remarkably, functionalization with a nonpolar methyl group yielded an improved separation efficiency compared to its parent compound. This work offers a good reference value for enhancing the C2H6/C2H4 separation efficiency of MOFs by engineering the pore microenvironment and dimensions via substituent manipulation.

Sorbent morphology is significant to Hg0 removal performance due to its serious impacts on the number and availability of adsorption sites and the mass transfer of the Hg0 removal process. Given this, a novel sorbent was obtained by in-situ growth of Co3O4 nanoparticles on channel walls of wood vessel which has regular mesoporous channels. The effects of synthetic conditions of hydrothermal temperature and NH4F concentration on sorbent morphology and Hg0 removal performance are investigated. Characterization results show that Co3O4 nanoparticles integrate a monolithic shell as synthesis temperature rises, while the nanoparticles grow radially with the increase of NH4F concentration. Radial growth of nanoparticles results in a higher crystallinity. The sorbent synthesized at hydrothermal temperature of 90 °C with the NH4F concentration of 0.05 M (denoted as T90C0.05) has uniform Co3O4 nanoparticle size, homogeneous dispersion and a larger specific surface area. Furthermore, T90C0.05 has a higher chemisorbed oxygen concentration and a higher Co3+/Co2+, which is of benefit to Hg0 removal process. Therefore, T90C0.05 has an excellent Hg0 removal efficiency of 97% with a high gas hourly space velocity of 180, 000 h−1 at 200 °C and the Co3O4 loading is only wt.5%. The effects of compounded flue gas components on the Hg0 removal performance were also studied. NO can weaken the inhibition effect of NH3 through the reaction between NO and NH3 forming labile [NH2NO]. In contrast, SO2 can not weaken the inhibition effect of NH3 due to the production coming from the reaction of SO2 and NH3 is stable at Hg0 removal temperature.

Molecule-aggregation organic electrodes in principle possess the “single-molecule-energy-storage” capability for metal-ion rechargeable batteries. Besides dissolution issue, the effect of possible solvent co-intercalation in liquid electrolytes also devalues the true performance of organic electrodes due to the weak Van der Waals forces among organic molecules. Herein, a small-molecule organic cathode called [N,N’-bis(2-anthraquinone)]-perylene-3,4,9,10-tetracarboxydiimide (PTCDI-DAQ, 200 mAh g-1) can deliver the unprecedented results in sodium-ion batteries (SIBs) by carefully choosing high-concentration electrolytes, which can offer more free sodium ions and decrease the solvent co-intercalation effect. Consequently, PTCDI-DAQ can deliver an ultra-stable capacity above 173 mAh g-1 during a long-lifetime operation test in half cells (6 months at least). In full cells, the resulting PTCDI-DAQ II Na3Bi SIBs can deliver a peak discharge capacity of 206 mAh g-1cathode with an average voltage of 1.2 V, running with no capacity decay over 4 months. Meanwhile, our PTCDI-DAQ II Na3Bi SIBs can re-store a world record of 70% capacity retention (142 mAh g-1cathode) at 20 A g-1cathode (100 C). To the best of our knowledge, PTCDI-DAQ can currently represent the best organic cathode for SIBs in the world; and the integrated performance of our PTCDI-DAQ II Na3Bi SIBs can compete with the best SIBs reported to date.small-molecule organic cathodes; ultra-stability; long lifespan; high rate; Na-ion batteries

New two-layer Ruddlesden—Popper (RP) oxide La0.25Sr2.75FeNiO7−δ (LSFN) in the combination of Sr3Fe2O7−δ and La3Ni2O7−δ was successfully synthesized and studied as the potential active single-phase and composite cathode for protonic ceramics fuel cells (PCFCs). LSFN with the tetragonal symmetrical structure (I4/mmm) is confirmed, and the co-existence of Fe3+/Fe4+ and Ni3+/Ni2+ couples is demonstrated by X-ray photoelectron spectrometer (XPS) analysis. The LSFN conductivity is apparently enhanced after Ni doping in Fe-site, and nearly three times those of Sr3Fe2O7−δ, which is directly related to the carrier concentration and conductor mechanism. Importantly, anode supported PCFCs using LSFN-BaZr0.1Ce0.7Y0.2O3−δ (LSFN-BZCY) composite cathode achieved high power density (426 mW·cm−2 at 650 °C) and low electrode interface polarization resistance (0.26 Ω·cm2). Besides, distribution of relaxation time (DRT) function technology was further used to analyse the electrode polarization processes. The observed three peaks (P1, P2, and P3) separated by DRT shifted to the high frequency region with the decreasing temperature, suggesting that the charge transfer at the electrode-electrolyte interfaces becomes more difficult at reduced temperatures. Preliminary results demonstrate that new two-layer RP phase LSFN can be a promising cathode candidate for PCFCs.

Doped BaZrO3 has outstanding stability and proton conductivity, and doped-ceria La2Ce2O7(LCO) has mixed conductivities of free-electron, oxygen-ion and proton, which are both potential electrolyte materials. Herein, one-step-co-fired BaZr0.8Y0.2O3-δ(BZY)-LCO composite electrolytes are prepared and characterized to give play to their respective advantages and avoid their shortcomings for low-temperature solid oxide fuel cells (LT-SOFCs). As for different components of BZY-LCO, the sintering activity increases with the increase of LCO content, however, the corresponding open circuit voltage decreases. Interestingly, the 30 %mol BZY-70 %mol LCO (3BZY-LCO) shows the best overall performance as functions of sintering activity, total conductivity, cell performance. As for the anode supported single cells, the maximum power density of 3BZY-LCO electrolyte can reach 0.581 W cm−2 at 750 °C using humidified hydrogen (3% H2O) as fuel. Preliminary experiment results suggest that the strategy of composite electrolyte can make up for the shortcomings of doped BaZrO3 and doped-ceria to a certain extent for LT-SOFCs.

Here, we report (C4H9)4NCuCl2 single crystals with a luminous intensity that remains largely the same after soaking in water for 24 h. (CH9)4NCuCl2 has a new type zero-dimensional framework, in which the isolated [CuCl2]- anions are wrapped by organic (C4H9)4N+ cations. As expected, (C4H9)4NCuCl2 shows a broad emission band at 508 nm with a photoluminescence quantum yield of approximately 82% at room temperature, stemming from self-trapped exciton (STE) emission. Temperature-dependent photoluminescence measurement reveals that there is an energy barrier ΔE (24.0 meV) between the intrinsic state and STE state, which leads to the increase in emission intensity with an increase in temperature (98-278 K), while the emission intensity begins to decrease when the temperature is higher than 278 K due to the effects of both thermal quenching and carrier scattering. Our findings provide a new idea for the design of lead-free anti-water stability metal halide materials.

Reversible solid oxide electrochemical cell (RSOC) is a competitive option which has attracted increasing focus on alleviating some environmental problems and energy crisis with the capability of reversibly operating in solid oxide fuel cell (SOFC) mode and solid oxide electrolysis cell (SOEC) mode [1]. Solid oxide cells (SOCs) have received increasingly attention due to their high efficiency and broad applications. However, electrodes with rapid hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), oxygen evolution reaction (OER) and sufficient durability play a key role in solid oxide cells. A multifunctional perovskite oxide La0.6Ca0.4Fe0.8Ni0.2O3-δ (LCFN) has been investigated as an electrode for SSOCs in our previous work. The results confirm that LCFN shows excellent ORR, OER, CO2-RR and HOR catalytic activity [2-3]. However, the investigation of LCFN for SOCs has been hindered due to the lack of stability. Herein, a novel perovskite La0.6Ca0.4Fe0.7Sc0.1Ni0.2O3-δ (LCFSN) is investigated as an electrode of SOCs. Its structural stability has been improved under H2 atmosphere. The polarization resistance (Rp) of the electrode LCFSN is only 0.147 Ω cm2 at 800 °C under air. The single cell Ni-YSZ/YSZ/GDC/LCFSN displays a peak power density of 1.36 W/cm2 in fuel cell mode and a low Rp value of 0.131 Ω cm2. Most importantly, the cell exhibits admirable durability of 130 h without apparent degradation. All these results suggest that LCFSN is a promising candidate electrode for SOCs.

Oxygen vacancies-rich iron-based perovskite-like oxides LaxSr3-xFe2O7-δ (x = 0, 0.25, 0.5) have been studied towards application as both anode and cathode materials for symmetrical solid oxide fuel cells (SSOFCs) at intermediate temperatures utilizing their excellent thermo-chemical structural stability. The conduction mechanism of LaxSr3-xFe2O7-δ was investigated according to the effect of La content on electrical conductivity and oxygen nonstoichiometry. Consequently, LaxSr3-xFe2O7-δ was used simultaneously as reversible symmetrical electrodes for YSZ electrolyte supported SSOFCs with GDC buffer layers. The maximum power density of LaxSr3-xFe2O7-δ-GDC symmetrical electrodes increased from 350 mW cm−2 to 480 mW cm−2 at 800 °C, and the corresponding cell polarization resistance decreased from 0.18 Ω cm2 to 0.16 Ω cm2, respectively. The enhanced performance is attributed to the improved electrical conductivity and electro-catalytic activity by the partial substitution of Sr with La. These results demonstrate that new iron-based perovskite-like oxides are promising for applications in intermediate temperatures SSOFCs.

Carbon materials have attracted abundant attentions and been utilized widely as anodes in rechargeable Li+/Na+/K+ ions batteries. Regarding the various radius of alkali-metal-ions, reversible intercalation and deintercalation in interlayers of carbons requires different interplanar spacing. In this work, N-doped graphene with tunable interplanar spacing is synthesized using graphitic carbon nitride (g-C3N4) as precursor with the assistance of polyvinylpyrrolidone (PVP). The obtained tunable interplanar spacing in the range from 0.34 nm to 0.45 nm with enlarged values is mainly ascribed to the high nitrogen doping levels (9.98–33.7 at. %), especially to the pyrrolic nitrogen. Serving as the anode materials in lithium ions batteries (LIBs) and sodium ions batteries (SIBs), promising specific capacities of 1236 mAh g−1 for LIBs and 300 mAh g−1 for SIBs at current density of 0.05 A g−1 and excellent cycling stability as well as acceptable rate capability are demonstrated for the resultant N-doped graphene. The influences of interplanar spacing on the electrochemical performances of LIBs and SIBs are investigated comparatively. This work outlines a facial route to synthesize N-doped graphene with tunable interplanar spacing, meeting the various requirements unitized as anodes in rechargeable Li+/Na+/K+ ions batteries.

Zero-dimensional lead-free organic-inorganic hybrid metal halides have drawn attention as a result of their local metal ion confinement structure and photoelectric properties. Herein, a lead-free compound of (Gua)3Cu2I5 (Gua = guanidine) with a different metal ion confinement has been discovered, which possesses a unique [Cu2I5]3- face-sharing tetrahedral dimer structure. First-principles calculation demonstrates the inherent nature of a direct band gap for (Gua)3Cu2I5, and its band gap of ∼2.98 eV was determined by experiments. Worthy of note is that (Gua)3Cu2I5 exhibits a highly efficient cool-white emission peaking at 481 nm, a full-width at half-maximum of 125 nm, a large Stokes shift, and a photoluminescence quantum efficiency of 96%, originating from self-trapped exciton emission. More importantly, (Gua)3Cu2I5 single crystals have a reversible thermoinduced luminescence characteristic due to a structural transition scaled by the electron-phonon coupling coefficients, which can be converted back and forth between cool-white and yellow color emission by heating or cooling treatment within a short time. In brief, as-synthesized (Gua)3Cu2I5 shows great potential for application both in single-component white solid-state lighting and sensitive temperature scaling.

Solid polymer electrolytes can significantly improve the safety and energy density of sodium-ion batteries compared with the liquid electrolytes. However, the low ionic conductivity and poor mechanical properties inhibit the practical application. In this paper, poly(ethylene oxide) (PEO) solid polymer electrolytes with enhanced ion conductivity are demonstrated by introducing inorganic solid electrolyte (beta-alumina) filler. With the presence of conductive beta-alumina filler, the ion conductivity of the resultant PEO polymer electrolyte is enhanced from 2.5*10–4 to 3.95*10–4 S cm−1. Applied in sodium-ion batteries (SIBs), the cell delivers an initial discharge capacity of 93.1 mAh g−1 and acceptable cycling performance (77.8 mAh g−1 after 100 cycles), which are significantly superior to that of the PEO solid polymer electrolyte without beta-alumina filler modification. The presented results prove that the ion conductivity of PEO polymer electrolyte can be enhanced by adding conductive beta-alumina, promoting its practical application in Na-ion all-solid-state batteries or other electrochemical energy storage systems.

The concentration of nucleating agent (NA) and flow fields are both important factors affecting the crystalline behavior and final properties of semicrystalline polymers. In this work, the concentr...

Electrolytes, the crucial and indispensable component of a battery system, dominate the interfacial chemistry and the overall performances of the battery. In this work, a poly(vinylidene fluoride-c...

Recently, zero-dimensional (0D) metal halides have made remarkable achievements in the field of optoelectronics due to their diverse structures and optical performances. Here, we report 0D (TBA)2Cu2I4 (TBA+ = tetrabutylammonium cation) single crystals (SCs), which shows a dual-emission band at 473 and 699 nm and a bright cool-white emission with a high photoluminescence quantum yield (PLQY) of 72.5% at room temperature (RT). The temperature-dependent emission spectra and Raman spectra show that a dual self-trapped exciton (STE) is present in this compound, and the external thermal energy can effectively regulate the population of STEs in the two emitting states, and thus the emission color can be changed from blue at a low temperature (78 K) to a cool-white emission at RT. More specifically, (TBA)2Cu2I4 SCs possess high anti-water stability, and can maintain highly efficient emission even if immersed in water for 24 hours. Also noteworthily, the high thermal stability, air stability and photostability of this component have also been proved.

Polyoxometalates (POMs) as molecule-based metal oxides have exhibited significant application in catalysis and materials science, but the synthesis of pristine POM nanomaterials still remains a challenge. In this work, we find a novel strategy of concentration-induced self-assembly for gaining pristine POM nanorods AgxH3−xPMo12O40 (denoted as AgHPMo12), which are synthesized only from both POMs and silver ion Ag+ in an aqueous solution at room temperature. The controllable concentrations of the cationic and anionic components in the aqueous solution become the critical factor for the successful synthesis. In addition, the photoelectric properties of AgHPMo12 nanorods were investigated as compared to those of AgHPMo12 particles, indicating a superior photoelectric performance of AgHPMo12 nanorods to AgHPMo12 particles. Furthermore, AgHPMo12 nanorods/phthalocyanine heterojunction photocatalysts were prepared for evaluating photocatalytic degradation of tetracycline hydrochloride, showing an efficient photocatalytic performance due to the advantages of the nanorods and type II heterostructure.

An insoluble small-molecule organic compound [N,N′-bis(2-anthraquinone)]-perylene-3,4,9,10-tetracarboxydiimide (PTCDI-DAQ) can be a high-performance cathode in Li-ion batteries (LIBs). In half cells, PTCDI-DAQ delivers a peak specific capacity of 229 mA h g−1, along with the good retention of 82% over 3 months. Meanwhile, PTCDI-DAQ can still hold a capacity of 46 mA h g−1 at 25 A g−1. By using the reduced state (Li4TP) of lithium terephthalate (Li2TP) as an organic anode in the all-organic Li-ion batteries (OLIBs), our OLIBs can realize a high-energy density of 296 W h kg−1cathode in the voltage range of 0.2–3.2 V and fulfill a long lifespan over 20 000 cycles. To the best of our knowledge, the comprehensive performance of our PTCDI-DAQ II Li4TP OLIBs is currently one of the best pure-organic LIBs in the world.

The industrialization of perovskite solar cells (PSCs) is based on the development of efficiency and stability. Here, a composite film of a polyethylenimine ethoxylated (PEIE) and tellurophene-based two-dimensional metal–organic framework (2D MOF) was introduced to realize the nondestructive passivation of TiO2. This interfacial layer can not only realize the effective passivation of TiO2, but can also further improve the morphology of the perovskite film. After the modification of the PEIE-2D MOF composite film, the morphology and crystallinity of the perovskite film are greatly optimized, the trap states in the TiO2 layer are reduced, and the electron transport in the device is enhanced, thus finally achieving highly efficient and stable FA0.25MA0.75PbI3 PSCs with a maximum efficiency of 22.22%. It was demonstrated that the reduced trap states and the smooth surface of the TiO2 electron transport layer are the reasons for the high performance of modified PSCs. This method provides a new way for improving the interface state to achieve highly efficient and stable PSCs.

Low-dimensional organic–inorganic hybrid metal halides have drawn intense attention due to their flexible structures and outstanding optical properties. However, the toxicity of lead halides hinders their future application in optoelectronic devices. Herein, we report a zero-dimensional (0D) lead-free compound of (TPA)2SbCl5 (TTA+ = tetrapropylammonium cation) single crystals (SCs), which crystallizes in a triclinic system with P symmetry. Interestingly, (TPA)2SbCl5 exhibits a single broad orange emission band at 610 nm under low-energy excitation (e.g., 375 nm) with a high photoluminescence quantum yield (PLQY) of 95.3%, while it shows a dual-band emission profile with an additional narrow emission band at 466 nm at high-energy excitation (e.g., 300 nm), which is formed by the transformation of the doublet of spin–orbit interactions into two individual STEs. The Raman spectra supplied clear evidence for the self-trapped exciton (STE) with clear multiphonon modes in (TPA)2SbCl5, which reflects its strong nonlinear electron–phonon coupling. The emission mechanism for the temperature-dependent dual emission can be attributed to the radiative transitions of singlet STEs and triplet STEs in [SbCl5]2− clusters. Moreover, a white-light-emitting diode (WLED) was also fabricated by mixing (TPA)2SbCl5 with green (Ba2SiO4:Eu2+) and blue (BaMgAl10O17:Eu2+) phosphors, which exhibited CIE coordinates of (3.48, 3.50), a correlated color temperature (CCT) of 4900 K, and a color rendering index (CRI) of 93.2. Our achievements illustrate that the lead-free compound of (TPA)2SbCl5 has great potential in solid-state lighting.

The interface issue between Na and the NASICON solid electrolyte is recognized as the dominant reason for the growth of Na metal dendrites. In this work, aSnS2 ultra-thin layer is fabricated on the surface of the Na3Zr2Si2PO12 electrolyte by a fast (1 min) and convenient (air atmosphere) pyrolysis method. A mixed-ion-electron conductor layer consisting of Na–Sn alloy and Na2S constructed in situ through the reaction between the Na metal anode and SnS2 can not only build a continuous and tight bonding interface between Na3Zr2Si2PO12 and Na, but also realize the uniform and rapid transfer of charge and Na+ flux at the interface, resulting in a stable interface during the Na deposition/stripping process. The Na symmetric cell with a maximum current density of 0.9 mA cm−2 can be stably operated at 0.1–0.4 mA cm−2 with low overpotential for a long time at room temperature. The Na3V2(PO4)3|Na3Zr2Si2PO12–SnS2|Na solid-state battery delivers excellent capacity retention ratios and rate performance, profiting from the constructed stable interface. This work proposes a facial strategy for the improvement of interface design, driving the application of inorganic solid electrolyte in solid-state batteries.

In this paper, we performed electric field measurements in a nanosecond DBD breakdown in ambient air using the electric field induced second harmonic generation technique, with a temporal resolution of approximate 5 ns. The measurements are in a diffuse plasma, and the emission intensity of the plasma is captured using an ICCD camera. Results including the non-zero electric field offset before the breakdown and the electric field during the breakdown, are obtained. The influence of the voltage amplitude is also investigated.

An energy-efficient method for further enhancing the shock wave generated by underwater electrical wire-array explosion at a fixed energy was developed. Based on the configuration of a cylindrical wire-array, the method was to replace one wire of 0.2-mm diameter with $N$ thinner wires, while the total mass of these $N$ wires was kept equal to the mass of that 0.2-mm wire. As the number of wires increased, the maximum wave pressure at the axis of the wire-array increased from 28 MPa for 1 wire of 0.2-mm diameter to about 90 MPa for 16 wires of 0.05-mm diameter. The shock wave generated by one single wire was proportional to ${1/}({N})^{1/2} $ rather than $1/N$ , which should be the reason for the enhancement. The interaction of shock waves from each single wire was discussed. It might be roughly divided into two kinds, “non-overlapping” and “overlapping.” The “non-overlapping” occurred only in the wire-array with not more than four wires. While propagating toward the axis of the wire-array, the shock waves from the wires did not overlap even when they were close to the axis. The shock wave at the axis is simply the summation of the shock waves from all wires. In contrast, the “overlapping” occurred in the wire-array with not less than seven wires. The shock waves from the wires overlapped even when they were far from the axis. Due to the converging effect of shock waves, the shock wave at the axis is considerably lower than the summation of shock waves from all wires, especially when the number of wires is larger.

Fine control of nitrogen-doping in carbon materials is an urgent issue with great challenges for the applications in energy storage devices. In this work, nitrogen-doped hollow carbon spheres (NHCS) with tunable nitrogen-doping properties are synthesized by using graphitic carbon nitride (g-C3N4) nanosheets as precursor and Zinc powder as the template. A series of characterization techniques were performed to evidence the successful transformation of NHCS from g-C3N4. The nitrogen-doping level from 12.76 at.% to 27.82 at.% and the relative doping fractions of pyridinic-N, pyrrolic-N and graphitic-N for the g–C3N4–derived carbon materials can be easily tuned by controlling the synthetic temperatures. Serving as Li-ions battery anodes, the resultant NHCS delivers an acceptable initial discharge capacity of 1012.4 mAh g−1 under a current density of 0.1 A g−1 and a promising cycling stability (1064.5 mAh g−1 after 400 cycles) as well as an excellent rate performance (360 mAh g−1 at 10 A g−1). This work provides a facile gateway to synthesize high nitrogen-doped carbon materials applying to energy storage devices, from nitrogen-rich g-C3N4 precursor.

In this work, sodium beta-alumina solid electrolytes with high β″-Al2O3 content and high density are synthesized through solid-state reaction method employing boehmite as alumina sources. The influences of sodium oxide dosage on the phase component, texture structure, and ionic conductivity as well as the application performances in sodium ions battery for the synthesized beta-alumina electrolytes are investigated in detail. High β″-Al2O3 content of 94.6% and density of 97.8% are obtained for the electrolyte sinters through adding suitable excess of Na2O content, owing to the compensation of Na loss and the formation of molten state during the high-temperature sintering process. High ion conductivity of 1.16 × 10−2 S/cm at 350 °C is recorded for the beta-alumina electrolyte sinters, resulting from its high β″-Al2O3 content and density. The resultant beta-alumina electrolyte applied in Na3V2(PO4)3/Na battery delivers an initial discharge capacity of 80.5 mAh g−1 at 0.5 C and a high capacity retention of 79.25% after 100 cycles.

A numerical model is developed to evaluate ethanol-fueled solid oxide fuel cells (E-SOFCs) with a Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3–δ (Ni-BZCYYb) external reformer owing to its high hydrophilia, carbon deposition resistance, and catalytic properties. This model is validated by the ethanol conversion and product selectivity with the introduction of the steam for adjusting the water-carbon ratio. The simulated E-SOFCs provide a suitable porosity and thickness for the Ni-BZCYYb external reformer, and the optimal control conditions are that the porosity is around 0.4, and the thickness is more than 4 mm for the best reforming effect, which can decrease the concentration polarization loss and improve cell performance. The carbon deposition boundaries and the equilibrium composition can be predicted by the thermodynamic equilibria calculation for E-SOFCs. The proposed model can give the optimization of the geometry design and operating conditions to avoid carbon deposition and improve the electrochemical performance of E-SOFCs.

Recently, low-dimensional organic-inorganic lead halide perovskites have attracted a great deal of attention due to their outstanding tunable broadband emission, while the toxicity of lead hinders their further application in the photoelectric field. Here, we report a novel lead-free Cu(I)-based organic-inorganic perovskite-related material of a (MA)4Cu2Br6 single crystal with zero-dimensional clusters, which is a unique Cu2Br64- corner-sharing tetrahedron dimer structure consisting of two connected tetrahedra. The single crystal displays a bright broadband green emission with a high photoluminescence with a quantum yield of ≤93%, a large Stokes shift, and a very long (microsecond) photoluminescence (PL) lifetime, resulting from self-trapped exciton emission. The direct band gap characteristic of (MA)4Cu2Br6 was proven by density functional theory calculation, and its band gap was determined by experiments to be ∼3.87 eV. In the temperature range of 98-258 K, the PL intensity increases gradually with an increase in temperature due to the deep trapping out of strong electro-phonon coupling, while the PL decreases when the temperature increases over 258 K due to phonon scattering. It is worth mentioning that this new material has high chemical and light stability, in contrast to the lead perovskite.

In this work, stable superparamagnetic core-shell Fe₂B@SiO₂ nanoparticles were prepared by "one pot" chemical reduction of ferric ion salts with NaBH₄ and silica shell coating in the presence of citric acid stabilizer. The X-ray (XRD) and selection of electron diffraction (SAED) revealed that Fe₂B@SiO₂ nanoparticles were chiefly composed of silica shell and Fe₂B with a small amount of α-Fe. Then, graphene oxide (GO) was assembled onto core-shell Fe₂B@SiO₂ nanoparticles for Epirubicin (EPI) loading and releasing, and the adsorption isotherm of EPI on Fe₂B@SiO₂@GO was analyzed. The results showed, the adsorption process includes two steps, due to the π-π stacking effect of EPI on the Fe₂B@SiO₂@GO. The EPI loading efficiency of the magnetic nanoparticles was as high as 90%, while the EPI-loaded core-shell Fe₂B@SiO₂ nanoparticles showed an obvious pH controlled drug release behavior, and showed lower cumulative release rate when pH is 7.4 than that when pH is 5.7. The prepared nanoparticles demonstrated potential application in killing tumor cells while minimizing the toxicity to normal tissues.

Polarization-sensitive photodetectors are highly desirable for high-performance optical signal capture and stray light shielding in order to enhance the capability for detection and identification of targets in dark, haze, and other complex environments. Usually, filters and polarizers are utilized for conventional devices to achieve polarization-sensitive detection. Herein, to simplify the optical system, a two-dimensional self-powered polarization-sensitive photodetector is fabricated based on a stacked GeSe/MoS2 van der Waals (vdW) heterojunction which facilitates efficient separation and transportation of the photogenerated carriers because of type-II band alignment. Accordingly, a high-performance self-powered photodetector is achieved with merits of a very large on-off ratio photocurrent at zero bias of currently 104 and a high responsivity (Rλ) of 105 mA/W with an external quantum efficiency of 24.2%. Furthermore, a broad spectral photoresponse is extended from 380 to 1064 nm owing to the high absorption coefficient in a wide spectral region. One of the key benefits from these highly anisotropic orthorhombic structures of layered GeSe is self-powered polarization-sensitive detection with a peak/valley ratio of up to 2.95. This is realized irradiating with a 532 nm wavelength laser with which a maximum photoresponsivity of up to 590 mA/W is reached when the input polarization is parallel to the armchair direction. This work provides a facile route to fabricate self-powered polarization-sensitive photodetectors from GeSe/MoS2 vdW heterojunctions for integrated optoelectronic devices.

In this work, the one- (OPA) and two-photon absorption (TPA) and transition characteristics of the porphyrin and fullerene donor–acceptor systems linked by thiophene oligomers are investigated theoretically. In the study of the transition characteristics of OPA and TPA, a combination of 2D and 3D visualization methods is used. During the OPA and TPA transitions of this D–A system, there is both superexchange charge transfer without thiophene oligomers and sequential charge transfer through thiophene oligomers. On this basis, there exist also charge recombination TPA excitations of the previous two kinds of charge transfer into an intrinsic process. The degree of polymerization of the thiophene oligomer significantly affects the efficiency of superexchange charge transfer and participates in excitation in units of quarter-thiophene. Finally, a method to enhance the charge transfer efficiency during TPA excitation is proposed, which is local excitation enhanced charge transfer excitation.

Titanium-substituted polyoxometalates related with the semiconductor TiO2 have potential applications in photocatalytic, photovoltaic and semiconducting materials. In this work, we synthesize two water-soluble titanium-containing polyoxomolybdates (NH4)8[(CH3)4N]2[Ti2(SbMo7O27)2]·15H2O (1) and (NH4)10[Ti2(AsMo7O27)2]·16H2O (2) by a conventional aqueous solution method. Ammonia water as a starting material could play dual roles of a pH adjustor and a hydrogen bond assistant, resulting in the formation of many strong hydrogen bonds in their crystal structures. The electrochemical properties of compounds 1 and 2 were investigated by cyclic voltammogram measurements, and the diffuse reflectance UV-vis spectra of 1 and 2 were recorded to calculate their semiconductor band gap (Eg) values. Furthermore, using the two compounds as semiconducting materials, we carried out the photoelectrochemical sensing of bisphenol A in aqueous solution, indicating that bisphenol A in aqueous solution could be detected by means of photocurrent change.

When the membrane material in the air field vibrates, it will drive the movement of the surrounding air. The aerodynamic force generated by the moving air will act on the membrane material in turn, resulting in the change of dynamic characteristics such as membrane vibration frequency. In this paper, the additional air mass produced by membrane vibration in air is studied. Firstly, under the assumption that the incoming flow is uniform and incompressible ideal potential flow, the additional air mass acting on the surface is derived by using the thin airfoil theory and potential flow theory respectively. Then, according to the first law of thermodynamics and the principle of aeroelasticity, the analytical expression of the additional air mass is derived. Finally, through a specific example, the variation of the additional air mass with the membrane material parameters and pretension, as well as the influence of the aerodynamic force on the vibration frequency and amplitude of the membrane is obtained.

Early stage of underwater electrical wire explosion was observed by shadowgraph. By decreasing initial energy, the early stage of wire explosion was slowed down and possible to capture shadow photos during phase transitions. The vaporization process of wire is usually axially non-uniform due to random local micro explosions along the wire. The degree of non-uniform will be significantly decreased when increasing the initial energy. During explosion of the wire, more than one shock waves were generated not only from phase transition, but also from different pulses of deposition power. A modified piston model was introduced to explain the phenomenon.

This paper thoroughly investigates the decomposition pathways of SF6 in the presence of organic insulator vapors by means of high level quantum chemistry calculations with density functional theory. Optimized molecular structures and vibrational frequencies of intermediate products (IM) and transition states (TS) are first reported in this work. Potential energy surface is then investigated with a more sophisticated CCSD method including zero-point energy corrections and the rate constants are calculated with transition state theory. The overall chemical decomposition pathways of SF6 + PTFE vapor are obtained which are consisted of 17 reactions with TS1–TS17. By analyzing the rate constants, reactions SF + C → S = CF → TS2 → F + SC, SF3 + C → TS7 → SF2CF → TS8 → SFCF2, SF4 + C → IM3 → TS11 → IM4 → SF3 + CF and SF5 + C → IM5 → TS15 → SF4 + CF are selected as main reactions in SF6 decomposition. The results are prerequisite to study the non-equilibrium compositions of SF6 + organic insulator vapor mixtures.

Highly active triple-conducting (proton-, oxygen-ion-, and electron-conducting) perovskite oxide BaCo0.4Fe0.4Zr0.1Y0.1O3-δ need to further optimize the electrochemical performance and chemical stability in carbon dioxide and water containing atmospheres, greatly limiting its widespread use in protonic ceramics fuel cells (PCFCs). Here, Ba-site deficient Ba0.9Co0.4Fe0.4Zr0.1Y0.1O3-δ (B9CFZY) was synthesized and investigated as a promising candidate concerning the chemical and structural stability, electrical conductivity and electrochemical performance. Anode-supported button cells with the prevalent BaZr0.1Ce0.7Y0.2O3-δ (BZCY) as electrolyte using B9CFZY and B9CFZY-BZCY cathodes, respectively, were fabricated and then measured at 700-550 °C. The maximum power density of the cells with B9CFZY-based cathodes increase from 452 mW cm−2 to 537 mW cm−2 at 700 °C, however, the corresponding polarization loss decreases from 0.30 to 0.15 Ω cm2 by adding proton-conducting BZCY. Importantly, to better explore the reasons for the improved electrochemical performance, the distribution function of relaxation time (DRT) is used to distinguish different electrode polarization processes of both cells. The results indicate the polarization peaks (P3) of cells with composite cathode resulting from oxygen gas adsorption and dissociation can be greatly accelerated as well as the polarization peaks (P2) resulting from oxygen species diffusion to three phase boundaries or active sites in the cathode. The dramatic improvements demonstrate Ba deficient B9CFZY-BZCY material can be a very competitive cathode material for PCFCs.

The relative vibration between the micro-milling cutter and workpiece influences the processing quality and tool life. To solve the difficult problem of measurement of vibration displacement between cutting tool and workpiece during micro-milling process, we designed a laser displacement sensor holder, which realizes the adjustment on multi degrees of freedom. A set of vibration displacement measurement system is developed, which utilizes laser displacement sensor to collect vibration signal during micro-milling process. The frequency of micro-milling force is obtained by using varying cutting parameters method. The relationship between cutting force amplitude, frequency and vibration displacement is ascertained by using neural network method to realize vibration displacement prediction under given cutting parameters. The research lays the foundation for vibration suppression of micro-milling, which can help improve surface quality and extend tool life.

Background There has been a surge of interest on velocity-based training (VBT) in recent years. However, it remains unclear whether VBT is more effective in improving strength, jump, linear sprint and change of direction speed (CODs) than the traditional 1RM percentage-based training (PBT). Objectives To compare the training effects in VBT vs. PBT upon strength, jump, linear sprint and CODs performance. Data sources Web of science, PubMed and China National Knowledge Infrastructure (CNKI). Study eligibility criteria The qualified studies for inclusion in the meta-analysis must have included a resistance training intervention that compared the effects of VBT and PBT on at least one measure of strength, jump, linear sprint and CODs with participants aged ≥16 yrs. and be written in English or Chinese. Methods The modified Pedro Scale was used to assess the risk of bias. Random-effects model was used to calculate the effects via the mean change and pre-SD (standard deviation). Mean difference (MD) or Standardized mean difference (SMD) was presented correspondently with 95% confidence interval (CI). Results Six studies met the inclusion criteria including a total of 124 participants aged 16 to 30 yrs. The differences of training effects between VBT and PBT were not significant in back squat 1RM (MD = 3.03kg; 95%CI: -3.55, 9.61; I2 = 0%) and load velocity 60%1RM (MD = 0.02m/s; 95%CI: -0.01,0.06; I2 = 0%), jump (SMD = 0.27; 95%CI: -0.15,0.7; I2 = 0%), linear sprint (MD = 0.01s; 95%CI: -0.06, 0.07; I2 = 0%), and CODs (SMD = 0.49; 95%CI: -0.14, 1.07; I2 = 0%). Conclusion Both VBT and PBT can enhance strength, jump, linear sprint and CODs performance effectively without significant group difference.

The development of the resistive switching cross-point array as the next-generation platform for high-density storage, in-memory computing and neuromorphic computing heavily relies on the improvement of the two component devices, volatile selector and nonvolatile memory, which have distinct operating current requirements. The perennial current-volatility dilemma that has been widely faced in various device implementations remains a major bottleneck. Here, we show that the device based on electrochemically active, low-thermal conductivity and low-melting temperature semiconducting tellurium filament can solve this dilemma, being able to function as either selector or memory in respective desired current ranges. Furthermore, we demonstrate one-selector-one-resistor behavior in a tandem of two identical Te-based devices, indicating the potential of Te-based device as a universal array building block. These nonconventional phenomena can be understood from a combination of unique electrical-thermal properties in Te. Preliminary device optimization efforts also indicate large and unique design space for Te-based resistive switching devices., Resistive switching devices have great promise for a wide variety of technological applications. Here, Yang et al demonstrate that electrochemically induced tellurium filament can give rise to resistive switching, and show that devices based on this can provide a number of advantages compared to metallic filament-based devices.

In this work, we characterize the formation and transition behaviors of a microplasma around a microstructured surface at different gas pressures via two-dimensional particle-in-cell/Monte Carlo collision simulations. It is found that the microdischarge occurs outside the cathode microcavities at the lowest pressure and starts penetrating the microcavities with a curved sheath edge as the pressure increases. At higher pressure, coupled periodic microhollow cathode discharges (MHCDs) are formed inside the microcavities. Further increasing the gas pressure results in the disappearance of the MHCDs, and the dominant discharge shifts outside of the microcavity, locating above the protrusion tips. The effect of the space charge shielding on the discharge and the conditions for MHCD formation are discussed. The macroscopic discharge parameters versus the gas pressure and the electron energy distributions are examined. The results are helpful for better understanding the microplasma formation around nonplanar electrode surface in microgaps, which inform the scaling, design, and optimization of microplasma array devices across a wide range of gas pressure regimes.

Underwater electrical wire array explosion is a promising approach to generating an extreme high pressure condition which plays a vital role in the investigation of high energy density physics 1 . For electrical explosion of a wire array, the simultaneity of phase transition will affect the pressure peak of converging shock wave in the vicinity of implosion axis 2 , thus, the current from pulsed power supply should be evenly distributed to each exploding wire. Two exploding wires in parallel were set in our experiments to study the distribution of current in the wire array, and the current flowing through each wire was obtained using a coaxial shunt resistor. It is found that the current in the two exploding wires will show a significant difference near the melting point, and then the current distributions tend to be uniform because of the negative temperature coefficient of electrical conductivity. After the formation of high-conductivity plasma, the uneven current distribution will reappear, and this non-uniformity behaves differently in different discharge modes, which may be related to ionization mechanisms. In addition, the sensitivity of the current uniformity to the geometric parameter errors of exploding wires is analyzed based on the magneto-hydrodynamic simulation, and the effect of nonuniform current distribution on the converging shock wave is also considered using hydrodynamic calculations.