Atomic Ratio Research Articles

Desulfurization of simulated and commercial liquid fuel on nano-ZnO fabricated walnut shells.

The current investigation involved the development of activated carbon, juglans regia activated carbon (JRACs), from walnut shells, scientifically known as Juglans regia. The ZnO nanorods were loaded on the activated carbon and referred to as ZnO@JRACs. Desulfurization efficiency was assessed through batch adsorption and compared to commercial activated carbon known as DARCO. The materials were characterized using PXRD (powder X-ray diffraction), FTIR (Fourier-transform infrared spectroscopy), ICP-AES (inductively coupled plasma atomic emission spectroscopy), BET (Brunauer-Emmett-Teller) surface area analysis, TEM (transmission electron microscopy) imaging, and TGA (thermal gravimetric analysis). The findings indicated that the materials have oxygen functionalities, a porous morphology, and a substantial specific surface area (BET) of 1269.92 m2/g for ZnO@JRACs. Zn atom concentration in the ZnO@JRACs surface was determined to be 1.16 atomic percent using ICP-AES. Desulfurization experiments were conducted on three liquid fuels, namely a single component model fuel, MSF (multicomponent simulated fuel), and commercial fuel (kerosene), under optimized conditions (8g/L adsorbent dosage in 10mL of fuel, 15min of contact time at room temperature). The conditions effectively removed ~ 98.9% of dibenzothiophene (DBT) from the single component model fuel. The observed order for adsorption capacity is as follows: ZnO@JRACs (63.6mgg-1) > JRACs (46.3mgg-1) > DARCO (26.1mgg-1). The analysis of multicomponent simulated fuel (MSF) using gas chromatography-flame photometric detector (GC-FPD) revealed significant removal percentages for different types of thiophenic sulfur. Specifically, the removal percentages were ~ 46.2%, 97.6%, and 99.4% for benzothiophene, dibenzothiophene, and 4, 6-dimethyldibenzothiophene, respectively. Kinetic studies have shown that the adsorption process is governed by a pseudo second-order reaction. Additional thermodynamic studies were conducted to further investigate the mechanism of adsorption. The spent synthesized composite ZnO@JRACs were thermally regenerated and can be reused for up to four cycles.

Unraveling the formation of Tb/Pd films by coupled reduction as targets for heavy ion-beam irradiation

This study provides insights into the formation of Tb/Pd films produced by electroplating in combination with the so-called coupled reduction technique. The use of 149Tb as an α-emitting radionuclide enabled for the first time the study of the distribution of Tb across the surface and along the thickness of the Pd bulk by means of radiography and α-spectroscopy combined with Monte Carlo simulations of the energy loss of emitted α-particles, respectively. Additionally, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were employed for surface analysis, whereas X-ray diffraction provided conclusive evidence of the formed crystalline phases. The obtained results indicate the formation of either the intermetallic phase TbPd3 or a Tb/Pd solid solution, depending on the heating time and temperature as well as the local Tb/Pd atomic ratio. These insights pave the way to the production of stable targets for heavy ion-beam irradiations as well as other applications.

Enhancing damping properties of Mg–Sn–Y alloys: The role of metastable clustering

The damping properties of Mg–Sn–Y alloys with varied Sn/Y atomic ratios and heat-treatment processes have been studied. In the as-cast state, the alloy with a Sn/Y ratio of 3:1 exhibits the highest damping property in the low strain region due to the low Y solid solution and small lattice distortion. After heat treatment with 480 °C and 24 h, the lattice distortion of the alloy with a Sn/Y atomic ratio of 1:1 is significantly reduced compared to the cast alloy, resulting in an ultra-high damping property in the low strain region (ε = 10−4, Q−1 = 0.023). This change in damping property is attributed to the presence of metastable clusters, which consume energy through atomic rearrangement, separation, and redissolution, thereby enhancing the damping property. However, excessively long heat treatment times or high temperatures are detrimental to the formation of these metastable clusters, leading to a decreased damping property.

In-situ carbon integration on atomically dispersed platinum metal oxide nanocomposites for hydrogen evolution reaction

In this study, a novel in-situ carbon growth technique by a modified sol gel synthesis method is presented. The carbon support developed on a transition metal oxide composite transforms the electronic conductivity and is engineered for hydrogen evolution reaction by a dispersion of unit atomic concentration of platinum. Through two different synthesis techniques, platinum dispersion is implemented on the metal oxide-carbon system, one by direct sol-gel technique and another by chemical reduction technique, whereby a homogeneous dispersion of the noble metal on the composite is achieved. Carbon-based cerium oxide and titanium oxide composites are used as the base material, and one atomic percentage of platinum metal is ensured while synthesizing each of the carbon composites. The functionality of these catalysts towards hydrogen evolution reaction in a 0.5 M H2SO4 acidic media revealed the synthesis technique's uniqueness and the effect of metal support interaction that plays a vital role in the electrocatalytic activity. The intrinsic activity of the titania system, along with enhanced metal support interaction due to highly enriched platinum availability on the surface of the substrate, provides for strong electrochemical activity. The titanium oxide carbon composite with platinum dispersed by hydrazine reduction exhibited the finest activity with an overpotential of just 44 mV at j = 10 mA/cm2 and a tafel slope of 118 mV/dec. The gas chromatographic analysis on platinum supported titania catalyst showcased better performance by a margin of four times than the commercial three weight percentage platinum supported carbon.

Influence of punch coating surface properties on sticking during the tableting process

Introduction The present study evaluates the sticking propensity of Uncoated steel, and chromium nitride (CrN), zirconium nitride (ZrN), titanium nitride (TiN) and Ultracoat punch coatings during the tableting process of microcrystalline cellulose (MCC) conducted on a Manesty® F3 single station tableting press. Methods Surface properties including surface roughness, surface free energy (SFE) and its components, the atomic percentage of surface polar functional groups and oxides measured with X-ray photoelectron spectroscopy were used to characterize the surface propensity to sticking. Results After five hours of tablet pressing, MCC powder particles were found to adhere to the TiN coated and the uncoated steel punches. Surface analysis show that surface roughness of all the tested punches was similar. The Lewis base SFE component (LB-comp) was found to govern the acid-base interactions of the tested surfaces, and its value was higher for punch surfaces affected by sticking. The surfaces exhibiting higher LB-comp are more prone to strong acid-base interactions with water molecules that evaporate from the powder bed during compression. Therefore, these surfaces adsorbed water and allow sticking through capillary adhesion force. Conclusion The total atomic percentage of the surface polar functional groups (PFG) and oxides was also high for the surfaces that stick to MCC during tableting, suggesting that hydrophilic molecules on the punch surface favor sticking.

Sink strength of grain boundaries for point defects in irradiated ferritic/martensitic steel

Dislocation-free ferritic/martensitic steel: F82H was prepared by heat-treatment in the appropriate condition in order to investigate the sink strength of grain boundaries for point defects. The size and the areal density of irradiation-induced secondary defects, such as dislocation loops and voids, were investigated in electron-irradiated F82H. The in-situ irradiation experiment resulted in the formation of a defect free zone and the gradient distribution of loop and cavity as a function of distance from boundaries, especially around prior austenite grain boundaries. The atomic density ratio of grain boundary planes is a key parameter in determining the width of defect free zone; a grain boundary with a higher atomic density ratio typically exhibits a wider defect free zone compared to one with a lower ratio. These results clearly indicate that the distribution of irradiation-induced secondary defects in ferritic/martensitic steels is not uniform and is likely controlled by the sink strength, as characterized by the atomic density ratio of grain boundary planes.

Correlation of microstructure and magnetic softness of Si-microalloying FeNiBCuSi nanocrystalline alloy revealed by nanoindentation

Abstract Compared to the commercial soft-magnetic alloys, the high saturation magnetic flux density (B s) and low coercivity (H c) of post-developed novel nanocrystalline alloys tend to realize the miniaturization and lightweight of electronic products, thus attracting great attention. In this work, we designed a new FeNiBCuSi formulation with a novel atomic ratio, and the microstructure evolution and magnetic softness were investigated. Microstructure analysis revealed that the amount of Si prompted the differential chemical fluctuations of Cu element, favoring the different nucleation and growth processes of α-Fe nanocrystals. Furthermore, microstructural defects associated with chemical heterogeneities were unveiled using the Maxwell–Voigt model with two Kelvin units and one Maxwell unit based on creeping analysis by nanoindentation. The defect, with a long relaxation time in relaxation spectra, was more likely to induce the formation of crystal nuclei that ultimately evolved into the α-Fe nanocrystals. As a result, Fe84Ni2B12.5Cu1Si0.5 alloy with refined uniform nanocrystalline microstructure exhibited excellent magnetic softness, including a high B s of 1.79 T and very low H c of 2.8 A/m. Our finding offers new insight into the influence of activated defects associated with chemical heterogeneities on the microstructures of nanocrystalline alloy with excellent magnetic softness.

Inherent carbon burial potential of lakes across China

Eutrophication is one of the most important factors for the increasing production of organic carbon in inland waters. Variations in primary productivity across lakes due to eutrophication complicate predictions regarding future carbon burial and management of carbon sequestration in lakes. Phosphorus, an essential nutrient for plants and notorious for eutrophication, often limits primary productivity in lakes. It is crucial to normalize organic carbon burial to the content of total phosphorus (TP) in the water column to compare the inherent carbon burial capacity across lakes. However, the absence of long-term observational data of TP in lake water columns has hindered the ability to do so. In this study, we first verified that TP in sediments of Chinese lakes could substitute for that in the water column to reflect the annual primary productivity of lakes. Then we defined the inherent carbon burial potential of lakes as the total organic carbon to TP atomic ratio (TOC/TP) in the sediments. We quantified the inherent carbon burial potential of 90 lakes across China, exploring its spatial distribution, temporal trends, and potential controlling factors. The inherent carbon burial potential, based on surface sediments, decreased from western to eastern China, ranging from 466.1 to 24.3 with a mean of 137.0 ± 87.4. Mean annual precipitation was negatively related, while mean lake depth was positively related to the inherent carbon burial potential of the lakes across China. Analysis of sediment cores revealed that the mean inherent carbon burial potential of the lakes across China increased from 75.1 to 122.9 since the 1950s. Inherent carbon burial potential of the lakes in southwestern and eastern China, however, decreased since the 1990s. Changes in the extent of cultivated land in the watersheds were positively related to variations in the inherent carbon burial potential of Chinese lakes in the past few decades.

Enhanced degradation of venlafaxine induced by Fe2O3/CeO2 heterostructures through the thermal transformation from type I to direct Z-scheme in heterogeneous photo-Fenton

Heterostructures based on Fe2O3/CeO2 were synthesized by coprecipitating iron and cerium salts, with 70 % and 50 % atomic percentage of iron, and heat treatment at 600 and 800 °C (Fe70Ce600, Fe50Ce600, Fe70Ce800, Fe50Ce800). The catalytic activity in the Fenton and photo-Fenton process was evaluated in the degradation of venlafaxine (VEN) using UV/Vis LEDs. Treatment at 800 °C promoted greater crystallinity, increased crystallite size, decreased specific area, and high absorption between 200 and 600 nm, and bandgap energy (Eg) between 1.6 and 3.0 eV were observed. The heat treatment promoted different mechanisms in heterostructure materials with type I (straddling) schemes for Fe70Ce600 and Fe50Ce600, type II for Fe50Ce800, and direct Z for Fe70Ce800 responsible for generating a higher concentration of HO• radicals, high oxidation-reduction power (Fe2+/Fe3+) and (Ce4+/Ce3+), greater effective separation of charge carriers, providing improved catalytic activity due to the synergy between heterogeneous photocatalysis and photo-Fenton processes. LC-MS/MS analysis identified 12 transformation products (TPs), involving hydroxylation reactions, demethylation, and loss of cyclohexanol. The transformation products TP2 and TP9 were exclusive to Fe70Ce800, confirming different mechanisms among the heterostructures.

Enhanced oxidation resistance in nano-lamellar CoCrFeNiNbx (0.45 ≤ x ≤ 0.55) eutectic high entropy alloy during cyclic oxidation at 700–1100 °C

We report the superior oxidation resistance of nano-lamellar CoCrFeNiNbx (x = 0.45, 0.50, 0.55 atom ratio) eutectic high entropy alloy (EHEA) at 700–1100 °C. The as-cast microstructure comprises of nano-lamellar eutectic FCC+Laves phases. The oxidation kinetics followed the parabolic rate in between 700–800 °C, whereas, near-parabolic kinetics is followed at 900 °C. The addition of Nb improves the oxidation and spallation resistance of the EHEAs. A protective outer-oxide layer containing Cr2O3, FeCr2O4-type spinels, whereas, an inner-oxide layer containing Nb2O5, CrNbO4 were formed during oxidation. The mechanism of protection and the superiority of EHEAs as high temperature alloy are explored.

Pt–Ni–Co trimetallic nanoparticles anchored on graphene oxide: An effective catalyst for ammonia-borane hydrolysis and direct electrooxidation of ammonia-borane in alkaline solution

In this study, graphene oxide supported platin, nickel and cobalt trimetallic nanoparticles (PtNiCo@GO) were prepared by the impregnation/reduction method. The catalytic performances of PtNiCo@GO catalysts prepared with different atomic ratios were investigated for hydrogen production and electro-oxidation of ammonia-borane (AB). For hydrolysis of ammonia-borane, Pt0.8Ni0.1Co0.1@GO catalyst exhibited higher catalytic activity than Pt0.6Ni0.2Co0.2@GO, Pt0.4Ni0.3Co0.3@GO, and Pt0.2Ni0.4Co0.4@GO. The hydrogen generation rate and turnover frequency values were found to be 540 mL min−1g−1 and 42.8 min−1, respectively, in the experiment conducted at 35 °C, 0.5 mmol AB, and 50 mg Pt0.8Ni0.1Co0.1@GO catalyst. The activation parameters (Ea, ΔH#, and ΔS#) in the catalytic hydrolysis of AB were obtained at 42.22 kJ/mol, 31.95 kJ/mol and −114.82 J/(mol × K), respectively. The effects of the PtNiCo@GO catalyst on AB electro-oxidation were made at a scanning rate of 100 mV/s in the potential range of - 1V/+1V against Ag/AgCl, and chronoamperometry measurements were made at constant potentials of - 0.2V, 0.1V and 0.4V. For cyclic voltammetry and chronoamperometry measurements, 5 mM [Fe(CN)6]3/4 (1 M KCl) redox probe and 1 M NaOH + 50 mM AB solution were used.

Highly efficient photocatalysis-Fenton degradation of antibiotics and phenol over sulfidated FeOCl under natural sunlight illumination

Sulfidated FeOCl is prepared as a heterogeneous photo-Fenton catalyst. And the surface sulfidation of FeOCl can remarkably accelerate the photoinduced charge separation and transfer, while also increase Fe2+/Fe3+ atomic ratio, leading to the boosted photo-Fenton activity in the presence of H2O2. Under irradiation of natural sunlight (light intensity: ∼80 mW·cm−2), over 10 mg sulfidated FeOCl catalyst with using 20 μL 15 % H2O2, 91.2 % of ofloxacin solution (50 mg·L−1) and 97.5 % of sulfisoxazole solution (60 mg·L−1) can be degraded in 80 min, and 99.6 % of phenol solution (625 mg·L−1) is decomposed in 4 h. Under irradiation of a white Light-Emitting Diode (LED) lamp (light intensity: 5 mW·cm−2), 99.8 % of ofloxacin solution is decomposed after treatment for 4 h. Moreover, this photo-Fenton degradation system displays a stable activity in a wide range of pH (1−10), diverse water bodies, and various coexisting ions with concertation from 1 mM to 500 mM. Moreover, sulfidated FeOCl catalyst coated on a frosted glass sheet exhibits excellent stability for degrading ofloxacin even in seven continuous cycles. Particularly, the non-toxicity of the treated ofloxacin, sulfisoxazole, and phenol solution, have been proven by testing their toxic effects on cabbage seed, bacteria, and human embryonic kidney cell, respectively.

Microstructures and properties of a novel cemented carbide prepared using a Co–Ni–Cu multiprincipal element alloy as the binder

A Co–Ni–Cu multiprincipal element alloy (MPEA) powder was successfully synthesized through coprecipitation. Results of energy dispersive spectroscopy (EDS) and X-ray fluorescence spectroscopy (XRF) revealed nearly equal atomic ratios for Co, Ni, and Cu in the Co–Ni–Cu MPEA powder. Moreover, X-ray diffraction (XRD) confirmed a single-phase face-centered cubic (fcc) structure in the Co–Ni–Cu MPEA powder. To explore the differences in microstructure and mechanical properties, we compared a novel WC–2Co–2Ni–2Cu cemented carbide, utilizing the Co–Ni–Cu MPEA as a binder, with conventional WC–6Co and WC–3Co–3Ni cemented carbides prepared via liquid phase sintering. This comparison was conducted using scanning electron microscopy, XRD, and mechanical properties testing. Observations revealed that the surfaces of WC grains in WC–2Co–2Ni–2Cu and WC–6Co appeared smooth and flat, while those in WC–3Co–3Ni exhibited roughness with numerous terraces. In addition, the average grain size was 0.96, 1.14, and 1.22 μm in WC–2Co–2Ni–2Cu, WC–6Co, and WC–3Co–3Ni, respectively. Notably, the Co–Ni–Cu MPEA inhibited WC grain growth. WC–2Co–2Ni–2Cu (1388 HV30) exhibited hardness similar to that of WC–6Co (1406 HV30) but the highest fracture toughness (9.04 MPa∙m1/2), while WC–3Co–3Ni (1332 HV30) presented the lowest hardness. Bending strength values were recorded at 2406 MPa for WC–2Co–2Ni–2Cu, 2816 MPa for WC–6Co, and 2645 MPa for WC–3Co–3Ni, with WC–6Co exhibiting the highest bending strength. Considering their microstructures, physical properties, and mechanical properties comprehensively, the novel cemented carbides exhibited only slightly reduced bending strength compared to conventional counterparts. Thus, the Co–Ni–Cu MPEA binder demonstrates promising potential as a replacement for the conventional Co metal binder.

Titanium Dioxide-Decorated and Silanized Electrospun Recycled Polyethylene Terephthalate (PET) Fibers for Filtration

Abstract Electrospinning methods have produced polymer-based non-woven fibers that have excellent filtration for use as air filter media, however most work have been focused on producing thinner fibers by reducing polymer loading. In this work, polyethylene terephthalate (PET) plastic from used soda plastic bottles was electrospun and decorated with nano-TiO2 to produce nonwoven media with antimicrobial properties. Electrospinning parameters were optimized to maintain higher loading percentage of PET to as much as 30% (w/v) with resulting fibers having an average diameter of 1.8 μm. Electrospun fiber mats were then treated with a silane-based binder for surface-decoration with nano-TiO2 coating to impart antimicrobial properties to these fibers. XRF mapping showed uniform coating of the nanoparticles. Atomic ratios from XRF of Ti to Si did not significantly change before and after ultrasonication washing signifying the covalent coating of the nanoparticles onto the fiber matrix.

Heterointerface of nickel-ferric hydroxide / cobalt-phosphide-boride boosting hydrazine-assisted water electrolysis

Sustainable H2 production based on hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) has attracted wide attention due to minimal energy consumption compared to overall water electrolysis. The present study focuses on the design and construction of heterostructured CoPB@NiFe–OH applied as efficient bifunctional catalysts to sustainable produce hydrogen and remove hydrazine in alkaline media. Impressively, CoPB@NiFe–OH heterointerface exhibits an HzOR potential of −135 mV at the current density of 10 mA cm−2 when the P to B atom ratio was 0.2, simultaneously an HER potential of −32 mV toward HER when the atom ratio of P and B was 0.5. Thus, hydrogen production without an outer voltage accompanied by a small current density output of 25 mA cm−2 is achieved, surpassing most reported catalysts. In addition, DFT calculations demonstrate the Co sites in CoPB upgrades H∗ adsorption, while the Ni sites in NiFe–OH optimizes the adsorption energy of N2H4∗ due to electron transfer from CoPB to NiFe–OH at the heterointerface, ultimately leading to exceptional wonderful performance in hydrazine-assistant water electrolysis via HER coupled with HzOR.

Hydrothermal carbonization of woody waste: Changes in the physicochemical properties and the structural evolution mechanisms of hydrochar during this process

The Chinese medicine residue (CMR) is composed of wet woody waste, including licorice and ephedra, so using hydrothermal carbonization (HTC) to recover renewable energy from the CMR is a suitable treatment method. An in-depth analysis of the physicochemical properties and structural evolution mechanism of hydrochars is helpful in fundamentally promoting the energy utilization of traditional Chinese medicine waste residue. Therefore, this study analyzed the physicochemical properties and morphological structure of hydrochar produced under varying HTC conditions using multiple testing methods. The evolution of the hydrochar's structural characteristics can be categorized into three stages: component decomposition, structural rearrangement, and carbonization. During the component decomposition and carbonization stages, numerous nanoscale micropores form within the hydrochar. These micropores' specific surface area and pore volume can reach up to 113.420 m2/g and 0.01913 cm3/g, respectively. The highest fractal dimension values for D1 and D2 are 2.6354 and 2.5565, while the maximum values for the microcrystalline stacking height (Lc) and the average number of crystalline layers (Nave) are 0.3354 and 1.9968, respectively. Consequently, the hydrochar produced during these stages exhibits a rougher pore surface and a more complex structure, making it more suitable for adsorbing heavy metals from soil and sequestering CO2. During the structural rearrangement stage, the hydrochar exhibits higher contents of fixed carbon (FC), MgO, P2O5, and a higher C/N atomic ratio, with maximum values of 38.51%, 0.99%, 1.12%, and 28.49, respectively. Thus, the hydrochar produced during this stage is more suitable for soil remediation and nutrient recovery.

Optimization of process parameters for preparing AlN nanopowders by combining carbon-containing droplet combustion and carbothermal reduction methods

In this research, AlN nano-powders were prepared by combining carbon-containing droplet combustion (CCDC) and carbothermal reduction (CR) methods. Firstly, Al2O3+C mixed precursor was synthesized by the CCDC method, and then AlN nano-powder was obtained by the carbothermal reduction of this CCDC precursor. The effects of urea and glucose contents, ignition temperature, and combustion atmosphere on precursors and AlN powders were studied in detail. The results showed that with the molar ratio of urea to aluminum nitrate (U/A) of 3, the atomic ratio of carbon to aluminum (C/Al) of 6, and the ignition temperature at 800 °C under air atmosphere, the prepared precursor was composed of hollow and spherical structure particles exhibiting rough and porous surface morphology with high specific surface area (SSA) (41.4 m2/g). AlN nano-powders obtained by the carbothermal reduction of this precursor were found to be consisted of fine particles with the size of 20–30 nm with high SSA of 39.9 m2/g.

Diamagnetic to Ferromagnetic Like Transition of Non-Stoichiometry Barium Titanate (BaTiO3-x) Prepared by Sol-gel Method

The oxygen vacancy properties are significant, creating ferromagnetic properties of material in metal oxide systems like dilute magnetic semiconductors. An aqueous sol-gel method has been used in the present study to synthesize non-stoichiometry BaTiO3-x polycrystalline. In an attempt of examining the oxygen deficiency consequences on the magnetic properties, the gel samples were sintered (1000◦C) at various times (6, 12, 18, and 24 hours) under a vacuum environment. This study employs an X-ray diffraction apparatus in terms of characterizing segments and structures of the samples. It also investigates morphology and element distribution on the surface of the samples exploiting an Electron microscope where Energy dispersive spectroscopy is supplied. For the purpose of characterizing the magnetic properties of the samples, it applies vibrating sample magnetometers. The chemical state of the element and its corresponding bond to other elements was identified using X-ray photoelectron spectroscopy. Single-phase compounds were observed. The crystal system is tetragonal, but the crystal parameters are different. Increase sintering time leads to increase crystallite size and decrease in micro strain. Moreover, sintering in a vacuum environment results in oxygen deficiency and leads to the atomic ratio of Ba/Ti change as the sintering time increases. The Ba/Ti ratio change affects the transformation from diamagnetic to ferromagnetic-like. The elements (Ba, Ti and O) chemical state is shown and its bonding to the corresponding element along with the X-ray photoelectron spectroscopy pattern of the BTX2 sample. The element of oxygen binds to Ti and Ba while Ba element exists in two chemical states.

Advanced multi-component FeCoCuAlMo intermetallic electrocatalysts for efficient and sustainable hydrogen evolution in alkaline freshwater and seawater

Electrolyzing seawater to produce hydrogen is a promising sustainable energy production technology. The current non-precious metal-based hydrogen evolution reaction (HER) electrocatalysts demonstrate inadequate catalytic activity and poor stability in seawater electrolyte. Therefore, developing stable and efficient non-precious metal-based HER electrocatalysts is a major challenge for achieving sustainable green energy development. This work reports a multi-component intermetallic catalyst FeCoCuAlMo prepared by arc melting and chemical dealloying methods. The electrocatalytic hydrogen evolution performance of catalysts with varying atomic ratios (FeCoCu)20(Al70Mo30)80, (FeCoCu)30(Al70Mo30)70, (FeCoCu)40(Al70Mo30)60, and (FeCoCu)50(Al70Mo30)50 in alkaline seawater and alkaline electrolyte was studied. The findings indicate that these catalysts primarily consist of AlMo3 and (Cu0.35Fe0.35Co0.3)Al, among which the dealloyed (FeCoCu)30(Al70Mo30)70 exhibits excellent catalytic activity with overpotentials of 137.54 and 116.91 mV at a current density of 100 mA/cm2 in alkaline seawater and alkaline electrolyte, respectively, outperforming most catalysts. Additionally, it demonstrated long-term stability in alkaline seawater and alkaline electrolyte for 250 and 400 h without significant decay at overpotentials of 236 mV and 276 mV, respectively. This improved performance can be attributed to the unique structure of the multi-component intermetallic compound, which provides good thermodynamic stability and synergistic effects among its constituents, thereby enhancing HER performance. Within this multi-component intermetallic compound, AlMo3 particles serve as the primary conductive medium to accelerate electron transfer, while (Cu0.35Fe0.35Co0.3)Al serves as the main active site, resulting in a stable structure that provides the catalyst with high catalytic activity and good stability. Thus, the (FeCoCu)30(Al70Mo30)70 electrocatalyst is a promising candidate for seawater electrolysis aimed at hydrogen production.

Development, process optimization and assessment of sustainable mobile biochar kiln for agricultural use

A novel and energy-efficient biochar kiln that can be operated in the field with few requirements has been developed. The generated syngas are recirculated into the combustion chamber to heat biomass. This study optimized the feedstock parameters, biochar yield, and economics of producing biochar from soybean straw using the Response Surface Methodology (RSM) based on Central Composite Design (CCD). The biochar kilns had an energy conversion efficiency of 47.02% and an overall kiln efficiency of 41.03% at steady-state operation over 500 °C. It produced an average of 29.43 ± 1.42% biochar with a minimal fuel-to-biochar ratio of 0.19 ± 0.02 and a payback period of 4.02 months. The statistical analysis confirmed that the characteristics of the feedstock affect the biochar output and economic aspects of the biochar production process. Based on the optimization studies, it was concluded that the feedstock's moisture content should be 8% and particle size should be 15 mm for higher biochar yield with maximum energy efficiency and benefit-cost ratio. Biochar produced at optimal conditions obtained from the optimization process was also characterized. Physical-chemical analysis reveals that biochar has a higher carbon content (79.38 ± 1.04 %) and a lower atomic ratio of H/C (0.696), O/C (0.14), and (N + O)/C (0.08), indicating higher carbon stability and aromaticity. The TGA analysis demonstrated the high thermal stability of biochar by showing a lower (2.15%) mass loss between the 343.8 and 407.1 °C temperature range. The SEM and TEM micrographs showed the microporous structure of the soybean straw biochar with a worm-like pattern and a cylindrical shape.