Mixed Atmosphere Research Articles

Self-powered wireless flexible sensing for food storage based on triboelectric-electromagnetic generator

In Controlled Atmosphere (CA) food storage, maintaining optimal conditions, including gas concentration, temperature, and humidity on the food surface, is crucial. This paper proposes the application of a self-powered wireless flexible sensing system based on a triboelectric-electromagnetic generator in food CA storage. To configure certain concentrations of mixed CA gases, we need to accurately control the volume of CA gas input into the mixed gas tank within a certain period, and the gas flow velocity in the pipeline will directly affect this factor. The gas flow velocity in the pipeline is detected by the CA gas flow velocity detection part (FVS) with an independent layer working mode triboelectric nanogenerator (FV-TENG) as the main component. Simultaneously, a flexible Temperature and Humidity Sensor (THS) affixed to the food surface provides real-time monitoring. EMG collects irregular wind energy in the CA warehouse to provide energy for the processing of information in the system and wireless transmission to the IoT cloud platform, realizing the system's self-power and wireless transmission. The self-powered wireless sensing system facilitates remote collection of CA gas flow velocity data, precise control of mixed atmosphere gas concentrations, and real-time monitoring of food surface temperature and humidity in the CA warehouse.

High-Performance Ni3(HHTP)2 Film-Based Flexible Field-Effect Transistor Gas Sensors.

Conductive metal-organic frameworks (MOFs) have received increasing attention in recent years and present high application potential as sensing elements in electronic sensors. In this study, flexible field-effect transistor (FET) sensors based on conductive MOF, i.e., Ni3(HHTP)2, have been constructed. This Ni3(HHTP)2 sensor has high sensitivity (detection limit of 56 ppb) as well as superior selectivity for NO2 detection at room temperature, which is demonstrated by accurate gas detection in a mixed gas atmosphere. Moreover, by employing six flexible substrates, i.e., polyimide (PI), tape (PET), facemask, paper cup, tablecloth, and take-out bag (textile), we successfully demonstrate the universality of the flexible sensor construction with conductive MOF as sensing film on various substrates. This study of conductive MOF-based flexible electronic sensors offers a new opportunity for a wide range of sensing applications with wearable and portable electronic devices.

Synergistic interactions of electronic modulation and low crystallization in Ru-RuO2/C heterostructure for highly efficient multifunctional electrocatalysis

Developing electrocatalysts with multifunctional performance is crucial for hydrogen energy storage and conversion, but still a great challenge. Herein, an efficient trifunctional electrocatalyst with heterostructure is fabricated by a sequential reduction and annealing approach. With different annealing atmospheres, Ru-RuO2/C electrocatalysts having different Ru/RuO2 atomic ratios or different crystallinities were achieved. Among these electrocatalysts, Ru-RuO2/C annealed from N2-air mixed atmosphere (Ru-RuO2/C 250NA) displays the most excellent performance, affording overpotential values of 30.63 mV for alkaline hydrogen evolution reaction (HER) and 273.42 mV for alkaline oxygen evolution reaction (OER) at 10 mA cm−2, much lower than those of state-of-the-art Pt/C (η10, HER = 46.57 mV) and RuO2 (η10, OER = 288.99 mV). Not only that, it also delivers favorable activity for alkaline hydrogen oxidation reaction (HOR), with 2.1 times of mass specific exchange current density than that of Pt/C. The experimental and theoretical investigations prove the electron rearrangement at Ru and RuO2 interface with abundant defects and amorphous/crystalline structures. The synergistic effect of dual active sites simultaneously optimizes H and OH as well as H2O adsorption energies, endowing the Ru-RuO2/C 250NA as the preferential electrocatalysts.

Harnessing intrinsic defect complexes for visible-light-driven photocatalytic activity in Delafossite CuAlO2

This study significantly enhances the photo(electro)catalytic capabilities of CuAlO2, a wide bandgap semiconductor, through targeted defect engineering. By employing a tailored solid-state reaction under a mixed oxygen-argon atmosphere, an intrinsic defect complex of [Oi+CuAl] into has been successfully integrated into CuAlO2, thereby expanding its light absorption to the visible spectrum. The optimized CuAlO2 sample, containing the [Oi+CuAl] complex, demonstrates a remarkable 2.13-fold increase in photocatalytic degradation of tetracycline hydrochloride under visible-light irradiation. The maximum incident photon-to-current conversion efficiency value is elevated from 0 to 3.27 %, and the photocatalytic water splitting hydrogen production rate is increased by 10.78-fold. Density functional theory calculations, in conjunction with experimental data, elucidate the role of the [Oi+CuAl] complex in facilitating visible-light absorption and improving the separation of photogenerated electron-hole pairs. Under simulated sunlight, the modified CuAlO2 sample exhibits a substantial 2.26-fold enhancement in photocatalytic degradation of tetracycline hydrochloride, a photocurrent density increase from 0.80 to 8.20 µA·cm−2, and a 1.13-fold increase in photocatalytic hydrogen production rate compared to defect-free CuAlO2. This research underscores the potential of strategic defect engineering to enhance visible-light-driven photo(electro)catalysis in wide bandgap semiconductors.

Bamboo-shaped N-doped carbon nanotubes encapsulated with Co nanoparticles for improved microwave absorption properties

High reflection loss and wide absorption bandwidth materials are in great demand to prevent electromagnetic pollution and military applications. The composites prepared by combining different components with good dielectric and magnetic losses are expected to achieve ideal absorbing performance. In this study, a composite of cobalt nanoparticles enveloped in nitrogen-doped bamboo-like carbon nanotubes (Co@N-CNTs) was prepared by one-step annealing the mixture of melamine and cobalt nitrate at 800 °C in a mixed atmosphere of hydrogen and argon. Co nanoparticles derived from the reaction between H2 and cobalt nitrate during the sintering process were used as catalysts to prompt the carbonization of melamine and the formation of the bamboo-shaped N-doped carbon nanotubes, thus forming the composite structure of bamboo-shaped N-doped carbon nanotubes encapsulated with Co nanoparticles. This Co@N-CNTs composite not only had an excellent dielectric loss and magnetic loss but also greatly improved its impedance matching, thus having good electromagnetic wave absorption performance. The coating made from the Co@N-CNTs composite had a maximum reflection loss (RL) of −35.89 dB at only 1.8 mm thickness at 14.1 GHz and possessed an effective absorption bandwidth of up to 4.91 GHz (12.35–17.26 GHz), suggesting it a high-performance and wide-absorption bandwidth composite material.

Effects of the Earth curvature on Mie-scattering radiances at high solar-sensor geometries based on Monte Carlo simulations.

Given the importance of vector radiative transfer models in ocean color remote sensing and a lack of suitable models capable of analyzing the Earth curvature effects on Mie-scattering radiances, this study presents an enhanced vector radiative transfer model for a spherical shell atmosphere geometry by the Monte Carlo method (MC-SRTM), considering the effects of Earth curvature, different atmospheric conditions, flat sea surface reflectance, polarization, high solar and sensor geometries, altitudes and wavelengths. A Monte Carlo photon transport model was employed to simulate the vector radiative transfer processes and their effects on the top-of-atmosphere (TOA) radiances. The accuracy of the MC-SRTM was verified by comparing its scalar model outputs from Henyey-Greenstein (HG) phase function with the Kattawar-Adams model results, and the mean relative differences were less than 2.75% and 4.33% for asymmetry factors (g-values) of 0.5 and 0.7, respectively. The vector mode results of MC-SRTM for a spherical shell geometry with the Mie-scattering phase matrix were compared with the PCOART-SA model results (from Polarized Coupled Ocean-Atmosphere Radiative Transfer model based on the pseudo-spherical assumption), and the mean relative differences were less than 2.67% when solar zenith angles (SZAs) > 70 ∘ and sensor viewing zenith angles (VZAs) < 60 ∘ for two aerosol models (coastal and tropospheric models). Based on the MC-SRTM, the effects of Earth curvature on TOA radiances at high SZAs and VZAs were analyzed. For pure aerosol atmosphere, the effects of Earth curvature on TOA radiances reached up to 5.36% for SZAs > 70 ∘ and VZAs < 60 ∘ and reduced to less than 2.60% for SZAs < 70 ∘ and VZAs > 60 ∘. The maximum Earth curvature effect of pure aerosol atmosphere was nearly same (10.06%) as that of the ideal molecule atmosphere. The results also showed no statistically significant differences for the aerosol-molecule mixed and pure aerosol atmospheres. Our study demonstrates that there is a need to consider the Earth curvature effects in the atmospheric correction of satellite ocean color data at high solar and sensor geometries.

Development of deoxidation process for off-grade titanium sponge using magnesium metal with wire mesh strainer type of crucible

In this study, the deoxidation process for off-grade titanium (Ti) sponge using magnesium (Mg) metal with a wire mesh strainer type of crucible was developed. Ti hydride (TiH2) feedstock, which was prepared by hydrogenating off-grade Ti sponge, was deoxidized using Mg in a molten magnesium chloride–potassium chloride salt at 933 K under an argon and 20% hydrogen (H2) mixed gas atmosphere. After deoxidation, the residual Mg-containing salt was separated in situ from the crucible to investigate the feasibility of minimizing salt loss during the leaching and production of pure TiH2. The results showed that the presence of residual Mg-containing salt inside the crucible strongly influenced whether a mixture of Ti and TiH2 or pure TiH2 was produced. When the salt was not sufficiently separated, a mixture of Ti and TiH2 was obtained and its oxygen (O) concentration was 0.121 mass% under certain conditions. Meanwhile, pure TiH2 was obtained by increasing the H2 gas flow rate during deoxidation. Therefore, these results demonstrate that the decrease of O concentration to below 0.180 mass% and the minimal loss of the salt are feasible.

Nickel Nanoparticles Protruding from Molybdenum Carbide Micropillars with Carbon Layer-Protected Biphasic 0D/1D Heterostructures for Efficient Water Splitting.

It remains a tremendous challenge to achieve high-efficiency bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) for hydrogen production by water splitting. Herein, a novel hybrid of 0D nickel nanoparticles dispersed on the one-dimensional (1D) molybdenum carbide micropillars embedded in the carbon layers (Ni/Mo2C@C) was successfully prepared on nickel foam by a facile pyrolysis strategy. During the synthesis process, the nickel nanoparticles and molybdenum carbide were simultaneously generated under H2 and C2H2 mixed atmospheres and conformally encapsulated in the carbon layers. Benefiting from the distinctive 0D/1D heterostructure and the synergistic effect of the biphasic Mo2C and Ni together with the protective effect of the carbon layer, the reduced activation energy barriers and fast catalytic reaction kinetics can be achieved, resulting in a small overpotential of 96 mV for the HER and 266 mV for the OER at the current density of 10 mA cm-2 together with excellent durability in 1.0 M KOH electrolyte. In addition, using the developed Ni/Mo2C@C as both the cathode and anode, the constructed electrolyzer exhibits a small voltage of 1.55 V for the overall water splitting. The novel designed Ni/Mo2C@C may give inspiration for the development of efficient bifunctional catalysts with low-cost transition metal elements for water splitting.

Interactions of graphene with oxidants in a mixed atmosphere: synergistic effects of O2/H2O and O2/CO2 on gasification reactivity and kinetics.

The gasification of carbon with O2, CO2, and H2O oxidants plays an important role in several energy-based applications. As most of the industrial gasification processes are conducted under mixed-atmosphere conditions, the oxidation of carbon in binary oxidant mixtures becomes crucially important. Using reactive force-field (ReaxFF) potentials, extensive MD simulations were carried out on the oxidation behavior of graphene in mixed O2/H2O and O2/CO2 environments for a range of gas compositions and temperatures. A graphene sheet with a line defect comprising of eight and four-membered rings was used as the starting carbon structure. In addition to enhanced carbon gasification with oxygen additions, MD simulations showed synergistic interactions between different oxidants and their net influence on the overall reactivities. The gasification levels achieved under the binary system were higher than the linear combination of contributions from individual oxidants. The addition of ∼40% O2 in the binary mix was identified as the region with the highest reactivity during the initial stages of gasification. The oxidation reactions with oxygen were found to start instantaneously in the presence of H2O or CO2 instead of the usual initial delay. A very fast reaction kinetics was also observed in the initial stages in the presence of oxygen. Our results show that the gasification reactions under H2O and CO2 started at lower temperatures than O2 thereby creating a partially oxidized structure. Due to the presence of a large number of activation sites, very high rates of gasification were achieved with oxygen. These findings could help identify optimal oxidant compositions towards maximizing carbon gasification and minimizing CO2 emissions.

Enhanced ionic conductivity of composite solid electrolyte by defective Li1.3Al0.3Ti1.7(PO4-y)3 for solid-state Li-ion batteries

Oxygen-deficient Li1.3Al0.3Ti1.7(PO4)3 (LATP) was prepared using a hydrothermal method followed by high-temperature calcination. Comprehensive analyses using X-ray powder diffraction (XRD), electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) conclusively demonstrated the successful preparation of oxygen-deficient LATPs under different calcination temperatures in an argon-hydrogen mixed atmosphere. These varying temperatures affected the concentration of oxygen defects in LATP. The hydrothermal precursor was calcined at 700 °C for 6 h to prepare an oxygen-deficient LATP, which was subsequently combined with polyacrylonitrile (PAN) to form a solid composite electrolyte. The composite exhibited a total ionic conductivity of 7.55 × 10−4 S cm−1 at 20 °C. Furthermore, when tested at 25 °C with a current density of 0.025 mA cm−2, the composite displayed good compatibility with a lithium metal anode. At a current density of 0.1 C, the initial discharge capacity was found to be 256.2 mA h g−1, which was maintained at 231.8 mA h g−1 after 100 cycles within the voltage range of 2.0–4.5 V. By judiciously modulating the oxygen defects concentration, it is possible to not only improve the ionic conductivity of the solid composite electrolyte but also to further enhance its discharge capacity.

The introduction of Mn component improves the selectivity of NO adsorption separation in simulated flue gas of Co‐MOF‐74 at ambient conditions

Synthesized of bimetallic Mn0.17Co0.83‐MOF‐74 via the solvent‐thermal method, which retained the same structure as that of monometallic MOF‐74, and the two metals were uniformly dispersed in the crystals of Mn0.17Co0.83‐MOF‐74. The introduction of Mn gave the Mn0.17Co0.83‐MOF‐74 a higher pore number than the monometallic MOF‐74, exposing more accessible metal active sites, and the in situ IR demonstrated that NO adsorption on Mn0.17Co0.83‐MOF‐74 was modelled as the linear adsorption of metal‐centred Co (II)⸱⸱⸱NO and Mn (II)⸱⸱⸱NO, with strong interactions of adsorbed NO with both metal sites, suggesting that the introduction of Mn provided new accessible metal adsorption sites for NO that increased the adsorption of NO. The NO adsorption capacity of bimetallic Mn0.17Co0.83‐MOF‐74 was significantly increased to 160.3 cc.g−1 at ambient conditions, and the adsorption selectivity of NO/CO2 achieved 397, which was 37% higher than monometallic Co‐MOF‐74, and 214% higher than Mn‐MOF‐74 at low pressure. Furthermore, when exposed to a simulated mixed atmosphere, the Mn0.17Co0.83‐MOF‐74 exhibited a NO/CO2 adsorption selectivity of 35.5 and demonstrated favourable recyclability. These findings indicated that the bimetallic Mn0.17Co0.83‐MOF‐74 outperforms traditional materials in the adsorption separation of flue gas NO, positioning it as a material of choice in this field.

A broad-spectrum gas sensor based on correlated two-dimensional electron gas

Designing a broad-spectrum gas sensor capable of identifying gas components in complex environments, such as mixed atmospheres or extreme temperatures, is a significant concern for various technologies, including energy, geological science, and planetary exploration. The main challenge lies in finding materials that exhibit high chemical stability and wide working temperature range. Materials that amplify signals through non-chemical methods could open up new sensing avenues. Here, we present the discovery of a broad-spectrum gas sensor utilizing correlated two-dimensional electron gas at a delta-doped LaAlO3/SrTiO3 interface with LaFeO3. Our study reveals that a back-gating on this two-dimensional electron gas can induce a non-volatile metal to insulator transition, which consequently can activate the two-dimensional electron gas to sensitively and quantitatively probe very broad gas species, no matter whether they are polar, non-polar, or inert gases. Different gas species cause resistance change at their sublimation or boiling temperature and a well-defined phase transition angle can quantitatively determine their partial pressures. Such unique correlated two-dimensional electron gas sensor is not affected by gas mixtures and maintains a wide operating temperature range. Furthermore, its readout is a simple measurement of electric resistance change, thus providing a very low-cost and high-efficient broad-spectrum sensing technique.

Experimental and theoretical investigations on the lattice defects and sintering atmosphere tuning the colossal permittivity of SrTiO3 ceramics

The Sr0.995La0.005TiO3 ceramics were fabricated with traditional solid-state methods under diverse sintering atmospheres. The dielectric properties have a significant correlation with the sintering atmosphere, while showing favorable temperature and frequency stability. As sintered in a mixed hydrogen-nitrogen atmosphere, Sr0.995La0.005TiO3 ceramics exhibited a colossal permittivity (ԑr ∼ 31307), low dielectric loss (tanδ ∼ 0.038) and good frequency stability synergistic temperature stability (−70 °C-180 °C, ΔC/C25°C ≤ ±15 %). The association mechanism of oxygen vacancies, lattice defects, and dielectric characteristics is evaluated in the context of experiments and first-principles. The phase structure and microstructure analysis revealed that the ceramics contained a two-phase structure with a SrTiO3 phase and a TiO2 second phase. The analysis of elemental valence and dielectric characterization demonstrated that defective dipoles, oxygen vacancies, and defect clusters resulting from non-homogeneous ion substitution are the major reasons for contributing to the colossal permittivity and low dielectric loss of the ceramics. This revealed that the electron-pinned defect dipole (EPDD) effect dominates in Sr0.995La0.005TiO3 ceramics. In addition, it can be established that the SrTiO3 phase and TiO2 phase contribute to the EPDD effect simultaneously, with SrTiO3 main phase taking the main role. According to the ELF plot analysis, when the content of oxygen vacancies is high, electrons accumulate at oxygen vacancies and defect clusters, leading to a high localization of electrons, which contributes to colossal permittivity and low dielectric loss of ceramics. The results are promising in colossal permittivity (CP) materials.

Effect of oxygen flow on electrical and optical properties of ITO films synthesized by magnetron sputtering method

The tin-doped indium oxide thin films were synthesized by DC magnetron sputtering on the surface of polished silicon samples and glass slides in a mixed argon-oxygen atmosphere. The other deposition parameters: operating pressure, magnetron power and substrate rotation speed were kept constant. Thickness and density of thin films were measured by X-ray Reflectometry. The effects of oxygen flow rate and substrate temperature on the optical and electrical properties were investigated. The electrical properties (resistivity, Hall mobility and charge concentration) of the thin films were measured by the Van der Pauw method using the Hall effect. The minimum value of resistivity 0.52 × 10-3 Ohm·cm, and maximum charge mobility 28 cm2V-1s-1 was achieved at an oxygen proportional gas mixture of 2.6% (0.71 sccm). The transmission spectra of the films were measured in the wavelength range from 300 to 1100 nm. The transmittance of all films exceeds 75% in the visible and near-infrared spectral ranges. It was found that increasing the oxygen flow rate and heating of the substrate up to optimal value 150°C led to an increase in the crystallinity of the films and, consequently, to an increase in the Hall mobility and the transmittance.

In-situ preparation of N-doped Bi0/OVs-BiVO4 photocatalysts with enhanced photocatalytic properties

Elemental doping, noble metal deposition and defect engineering have proven to be effective strategies to enhance the photogenerated charge pairs separation behavior of semiconductor materials and ameliorate their photocatalytic performance. In this study, N-doped Bi0/OVs-BiVO4 photocatalysts were constructed in-situ by calcining BiVO4 precursors under a hydrogen/nitrogen atmosphere. The experimental results demonstrate the successful reduction and loading of Bi0 onto the BiVO4 surface and the introduction of N doing and oxygen vacancies (OVs). The optical absorption range of BiVO4 is broadened by the synergistic effect of the surface plasmon resonance (SPR) effect of Bi0, N-doping and OVs, inducing enhanced separation efficiency of the photoinduced carriers. The photocatalytic degradation rate constant of Rhodamine B (RhB) on samples treated with a hydrogen/nitrogen atmosphere for 10 min under simulated sunlight irradiation is 4.8 times better than that on the blank BiVO4. The enhanced photocatalytic performance of N-doped Bi0/OVs-BiVO4 originates from the synergistic effect of SPR effect of Bi0, N-doping and OVs. This work highlights that the improvement of BiVO4 photocatalytic property can be achieved by calcining BiVO4 under a hydrogen/nitrogen mixed atmosphere.

Highly sensitive chemoresistor based on Ag/TiO2/FTO sandwich structure for evaluation of component concentration in mixed ambient

The performance of membrane electrode assemblies (MEAs) in direct methanol fuel cells (DMFCs) can be greatly affected by ethanol as an impurity in methanol fuels. It is thus necessary to explore an effective method for accurately detecting the ethanol concentration in a mixed atmosphere of methanol and ethanol. Herein, we developed a chemoresistor based on Ag/TiO2/FTO sandwich structure and achieved accurate prediction for the concentration of each component in methanol-ethanol mixed atmosphere. First principles calculations were first performed to reveal the gas adsorption characteristics of TiO2 sensitive layer in different resistive state. It was indicated that methanol and ethanol molecules could be clearly distinguished by TiO2-based device in the high resistive state. In the gas-sensing test, the response value of Ag/TiO2/FTO chemoresistor in the high resistive state to 1 ppm methanol was 2.55, 14.8, 13.19, 15.04 and 17.34 times higher than that of the same concentration of ethanol, acetone, isopropanol, acetic acid and methyl formate, respectively. Meanwhile, when the device was in direct current mode after the response, an ultra-fast recovery characteristic (0.7 s) was observed due to the resistive switching function. Finally, the prediction of the component gas concentration in the methanol-ethanol mixed atmosphere was achieved by combining the optimized neural network algorithm. The present work brings new inspiration for future research on gas sensors.

Impact of Ion-Mixing Entropy on Orientational Preferences of DNA Helices: FRET Measurements and Computer Simulations.

Biological processes require DNA and RNA helices to pack together in specific interhelical orientations. While electrostatic repulsion between backbone charges is expected to be maximized when helices are in parallel alignment, such orientations are commonplace in nature. To better understand how the repulsion is overcome, we used experimental and computational approaches to investigate how the orientational preferences of DNA helices depend on the concentration and valence of mobile cations. We used Förster resonance energy transfer (FRET) to probe the relative orientations of two 24-bp helices held together via a freely rotating PEG linker. At low cation concentrations, the helices preferred more "cross"-like orientations over those closer to parallel, and this preference was reduced with increasing salt concentrations. The results were in good quantitative agreement with Poisson-Boltzmann (PB) calculations for monovalent salt (Na+). However, PB underestimated the ability of mixtures of monovalent and divalent ions (Mg2+) to reduce the conformational preference. As a complementary approach, we performed all-atom molecular dynamics (MD) simulations and found better agreement with the experimental results. While MD and PB predict similar electrostatic forces, MD predicts a greater accumulation of Mg2+ in the ion atmosphere surrounding the DNA. Mg2+ occupancy is predicted to be greater in conformations close to the parallel orientation than in conformations close to the crossed orientation, enabling a greater release of Na+ ions and providing an entropic gain (one bound ion for two released). MD predicts an entropy gain larger than that of PB because of the increased Mg2+ occupancy. The entropy changes have a negligible effect at low Mg2+ concentrations because the free energies are dominated by electrostatic repulsion. However, as the Mg2+ concentration increases, charge screening is more effective and the mixing entropy produces readily detectable changes in packing preferences. Our results underline the importance of mixing entropy of counterions in nucleic acid interactions and provide a new understanding on the impact of a mixed ion atmosphere on the packing of DNA helices.

Production of hydrogen-rich syngas through microwave-assisted gasification of sewage sludge in steam-CO2 atmosphere

Microwave-assisted gasification (MWG) of sewage sludge (SS) was conducted, and the influence of gasification agents, i.e., steam and CO2, on the production of syngas and the generation path of H2 were systematically investigated. The results showed that the steam-CO2 mixed atmosphere was helpful to increase the yield of syngas (with the maximum yield of 45.3 wt%), and improve the quality of syngas. The maximum concentration of H2 reached 63.73 vol% (with H2 and CO total concentration of 68.93 vol%) when the steam/CO2 ratio (vol./vol.) was 36, and the maximum high heating value (HHV) of the syngas was about 10.51 MJ/Nm3 close to that of commercial syngas. H2 was mainly produced between 400 and 700 °C, and the maximum concentration could reach 76.2 vol% at 700 °C under the steam/CO2 ratio of 36. Steam and CO2 showed a good synergistic effect to jointly promote the production of H2 during MWG. The produced tar was mainly composed of hydrocarbons, oxygen-containing compounds and nitrogen-containing compounds, and steam could promote the formation of oxygen-containing compounds in tar. With the increase of steam/CO2 ratio, a large amount of fixed carbon was consumed through Boudouard reaction and steam reforming reaction. More than 50 % of P and K in SS were retained in char, which makes it a valuable product for soil amendment. Additionally, it was calculated that the MWG of 1 kg SS could be converted into 7801 kJ of electric energy through SOFCs, which could totally replace the electrical energy required for MWG of 1 kg SS, and the energy recovery efficiency (η) could be increased to 93.64 % in large-scale production.

Release characteristics of chromium and sulfur during cothermal disposal of waste tires and sludge: An experimental and DFT study

Chromium (Cr) and sulfur-containing pollutants (S) are released during thermal disposal of municipal sludge (MS) and waste tires (WTs). In this paper, the effects of the mixing ratio, temperature, atmosphere, and CaO on Cr release were determined, and the mechanism for Cr trapping during CaO sulfation was revealed with density functional theory (DFT). The MW (MS and WTs) thermal decomposition behavior, sulfur-containing pollutant release, and kinetic parameters were analyzed. The results showed that the thermal disposal of MW at 850 °C under flue gas immobilized the Cr, and the relative enrichment (RE) for Cr reached 92.66 % when the proportion of WTs was 50 %. DFT calculations revealed the effect of CaO sulfation on Cr adsorption. The energies for CrOOH adsorption on the (001) surface of CaO, and the (001) surface of CaSO4 decreased sequentially. The products of the CrOOH transformations in the flue gas, CrCl3 and CrO2Cl2, also diminished in that order for the corresponding surfaces. Typical decomposition steps were observed, including volatilization of water and small hydrocarbons, cracking of hydrocarbons, and transformations of inorganic materials at higher temperatures. H2S, SO2, CH3SH, and COS were the main sulfur-containing pollutants released during thermal disposal.

Morphological changes, He desorption behaviors, and He bubble evolution of He-charged Cu films prepared by DC magnetron sputtering during annealing

He-charged Cu films were prepared at room temperature by direct current (DC) magnetron sputtering in a He/Ar mixed atmosphere. Morphological changes, He desorption behaviors, and He bubble evolution of He-charged Cu films after the annealing treatments at different temperatures were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The results of SEM revealed that some blisters and pinholes were found at the surface and cross-section of He-charged Cu films after the annealing. The results of TDS profiles suggested that different kinds of He could be introduced into Cu films by a magnetron sputtering method. TEM analysis suggested that nano-sized He bubbles could be formed in as-deposited Cu films, and He bubble size increased with the increasing annealing temperature. The growth mechanism of helium bubbles in Cu film was suggested to originate from the migration and coalescence (MC) mechanism.