Search

High conversion rate and selectivity are challenges for CO2 utilization through catalytic reverse water gas shift (RWGS) reaction. Herein, a novel mesoporous biochar (MB) supported Cu-Mo2C nano-interface was prepared by consecutive physical activation of coconut shells followed by carbothermal hydrogen reduction of bimetal. As compared with traditional carbon materials, this MB exhibited ultra-high specific surface area (2693 m2 g–1) and mesopore volume of mesopore (0.81 cm3 g–1) with a narrow distribution (2–5 nm), responsible for the high dispersion of binary Cu-Mo2C sites, CO2 adsorption and mass transfer in the reaction system. Moderate carbothermal reduction led to the sufficient reduction of Mo ion with carbon matrix of MB and dispersive growth of nano Cu-Mo2C binary sites (~ 6.1 nm) on the surface of MB. Cu+ species were formed from Cu0 via electron transfer and showed high dispersion with simultaneous boosted bimetal loading due to the strong interaction between nano Mo2C and Cu. These were advantageous to the intrinsic activity and stability of the Cu-Mo2C binary sites and their accessibility to the reactant molecules. Under the RWGS reaction conditions of 500 °C, atmospheric pressure, and 300,000 ml/g/h gas hour space velocity, the CO2 conversion rate over Cu-Mo2C/MB reached 27.74 × 10–5 molCO2/gcat/s at very low H2 partial pressure, which was more than twice that over traditional carbon supported Cu-Mo2C catalysts. In addition, this catalyst exhibited 99.08% CO selectivity and high stability for more than 50 h without a decrease in activity and selectivity. This study offers a new development strategy and a promising candidate for industrial RWGS. Highlights: Coconut shell derived ordered mesoporous biochar with ultra-high SBET and mesopore volume was fabricated. Mesoporous biochar facilitates nano Cu-Mo2C interface formation, CO2 adsorption and mass transfer. Strong interaction between Mo2C and Cu leads to electron transfer and anchoring of Cu. CO2 conversion rate over Cu-Mo2C/MB was twice that over Cu-Mo2C/traditional carbon. The catalyst exhibited 99.1% CO selectivity and high stability for more than 50 h. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) with edge‐located metal active sites exhibit superior oxygen reduction reaction (ORR) performance due to their narrower energy gap and higher electron density. However, controllably designing such active sites to fully reveal their advantages remains challenging. Herein, rich edge‐located Fe‐N4 active sites anchored in hierarchically porous carbon nanofibers (denoted as e1‐Fe‐N‐C) are fabricated via an in situ zinc‐assisted thermal etching strategy. The e1‐Fe‐N‐C catalyst demonstrates superior alkaline ORR activity compared to counterparts with fewer edge‐located Fe‐N4 sites and commercial Pt/C. Density functional theory calculations show that the accumulation of more negative charges near the Fe‐N and the formation of partially reduced Fe state in the edge‐located Fe‐N4 sites reduce the energy barrier for the ORR process. Additionally, the unique hierarchically porous structures with mesopores and macropores facilitate full utilization of the active sites and enhance long‐range mass transfer. The zinc–air battery (ZAB) assembled with e1‐Fe‐N‐C has a peak power density of 198.9 mW cm−2, superior to commercial Pt/C (152.3 mW cm−2). The present strategy by facile controlling the amount of the zinc acetate template systematically demonstrates the superiority of edge‐located Fe‐N4 sites, providing a new design avenue for rational defect engineering to achieve high‐performance ORR. [ABSTRACT FROM AUTHOR]

The significant role of the cathodic binder in modulating mass transport within the catalyst layer (CL) of fuel cells is essential for optimizing cell performance. This investigation focuses on enhancing the membrane electrode assembly (MEA) through the utilization of a short‐side‐chain perfluoro‐sulfonic acid (SSC‐PFSA) ionomer as the cathode binder, referred to as SSC‐MEA. This study meticulously visualizes the distinctive interpenetrating networks of ionomers and catalysts, and explicitly clarifies the triple‐phase interface, unveiling the transport‐friendly microstructure and transport mechanisms inherent in SSC‐MEA. The SSC‐MEA exhibits advantageous microstructural features, including a better‐connected ionomer network and well‐organized hierarchical porous structure, culminating in superior mass transfer properties. Relative to the MEA bonded by long‐side‐chain perfluoro‐sulfonic acid (LSC‐PFSA) ionomer, noted as LSC‐MEA, SSC‐MEA exhibits a notable peak power density (1.23 W cm−2), efficient O2 transport, and remarkable proton conductivity (65% improvement) at 65 °C and 70% relativity humidity (RH). These findings establish crucial insights into the intricate morphology‐transport‐performance relationship in the CL, thereby providing strategic guidance for developing highly efficient MEA. [ABSTRACT FROM AUTHOR]

Although optimizing the design of thermal conductive frameworks to promote the collection, transportation, and storage of thermal energy in composite phase change materials (CPCMs) is widely studied, the research on oriented layered thermal conductive frameworks is still in the exploratory stage. Taking inspiration from the bidirectional ice template strategy, a new research approach is proposed on the influence of “oriented micro‐unit” in thermal conductivity frameworks on the photothermal mass transfer of CPCMs. Three aramid nanofibers graphene nanosheets aerogels with different “oriented micro‐unit” structures are prepared by the high‐energy ball milling and bidirectional freezing. The enthalpy values of the composite materials are within the range of 146–152 J g−1. Photothermal conversion experiments, hot plate mass transfer experiments, solar‐thermal‐electric energy conversion experiments and multi‐physics field simulation analysis jointly show that the CPCMs with a “back‐to‐back” radial layered structure behaves the most outstanding photothermal conversion ability and heat transfer performance, with an increase in thermal conductivity of 173.3%, a photothermal conversion efficiency of 91.9%, and the maximum solar‐thermal‐electric output voltage of 303.3 mV. The design of “oriented micro‐unit” opens up new ideas for CPCMs in the field where directional heat transfer is required. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) are crucial for the efficient utilization of hydrogen. Currently, their efficiency is mainly limited by the slow kinetics of the cathode oxygen reduction reaction (ORR) and the poisoning effect between ionomers and catalytic sites, particularly with Pt‐based catalysts. Recent works suggest that the emerging porous carbon‐supported catalysts hold promise in mitigating these challenges by ensuring fast kinetics while alleviating the poisoning. This review examines porous carbon‐supported catalysts for PEMFC cathodes, covering synthesis methods, structure and performance evaluation, and future prospects, with an emphasis on the influence of porous carbon support on PEMFC performance. On one hand, the rational design of pore structure in carbon support can help optimize the location of the active sites and enhance mass transfer. On the other hand, diverse pore structures provide a platform for gaining a deeper understanding of the mechanisms behind microscale mass transfer and reaction at the three‐phase boundaries. This review aims to inspire innovative strategies for the precise synthesis of porous carbon‐supported catalysts with various pore structures to further boost PEMFC performance. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of alkynes to alkenes using a low‐cost non‐noble metal catalyst is urgently desirable but challenging because of their over‐hydrogenation to undesired alkanes. Herein, a series of hierarchical N‐doped carbon nanosheets anchored bimetallic oxides were successfully fabricated. The resultant composite catalysts had advantages associated with not only two‐dimensionality (2D) nanosheets with highly active sites and fast mass transfer, but also bimetallic oxides that dissociate and transfer hydrogen with the assistance of the oxygen vacancies. Furthermore, the bimetallic oxides combined with the advantages of high activity of Ni and the selectivity regulation of Co. Benefiting from these advantages, the catalytic performance of CoNiO2−ZnCo2O4/NC NSs can reach nearly full conversion with 92 % selectivity at moderate reaction conditions and can keep excellent selectivity even prolonging the reaction time to 12 h, outperforming CoNiO2−ZnCo2O4/NC NPs, CoO−ZnCo2O4/NC NSs, and the commercial Lindlar catalysts, which demonstrate the huge potential for selective hydrogenation applications. [ABSTRACT FROM AUTHOR]

In the present study, the experimental intensification and modeling of the extraction process of antioxidants from rice husks using different organic solvents (ethanol, methanol, and acetone, and their mixtures with water) were analyzed and discussed. The best experimental extraction conditions to recover polyphenols from rice husks were identified, and the extraction kinetic data were modeled using the mechanistic and pseudo–second‐order models. The experimental results showed that the solvent‐based extraction of polyphenols from rice husks was endothermic where the ethanol and methanol offered the best separation performance. The polyphenol extraction process using ethanol and acetone was mainly influenced by the percentage of water contained in the solvent mixture used as separation medium, whereas the extraction temperature significantly affected the polyphenol extraction with methanol. The rice husk‐based extracts obtained with methanol and ethanol showed the highest total content of polyphenols (66.72 and 60.68 of gallic acid equivalent/g of biomass) and antioxidant capacity (71.93% and 72.02% 2,2‐diphenyl‐1‐picrylhydrazyl [DPPH] inhibition). The mechanistic model offered the best performance to describe the experimental polyphenol extraction, and its results were used to discuss and analyze the mass transfer parameters associated with the intraparticle diffusion of this extraction process. These results contribute to the valorization of rice husk residues as a potential feedstock to be incorporated in the biorefinery context for obtaining value‐added products. [ABSTRACT FROM AUTHOR]

Developing efficient oxygen electrocatalysts with low cost, high catalytic activity, and robust stability remains a formidable challenge for rechargeable zinc–air batteries (ZABs). Herein, highly dispersed ultrasmall PtPdFeCoNi high‐entropy alloy nanoparticles with a size of ≈ 2 nm and randomly distributed multimetallic single atoms spatially immobilized on the 3D hierarchically ordered porous nitrogen‐doped carbon skeleton (denoted as PtPdFeCoNi/HOPNC) are successfully synthesized via ultra‐rapid Joule heating process. The spatial immobilization on 3D HOPNC skeleton is the key to the high dispersion of multi‐active sites of oxygen electrocatalysts, and the formed hierarchical pore structure is conducive to the successful construction of the rapid mass transfer channel. As a result, the as‐prepared PtPdFeCoNi/HOPNC exhibits a positive half‐wave potential of 0.866 V versus RHE for oxygen reduction reaction (ORR), a low overpotential of 310 mV at 10 mA cm−2 for oxygen evolution reaction (OER), and low Tafel slopes for both ORR and OER. Furthermore, ZAB using PtPdFeCoNi/HOPNC as bifunctional oxygen catalysts exhibits excellent rate performances and superior cycling stability, surpassing that of a commercial Pt/C‐RuO2 mixture. The spatial immobilization strategy of HOPNC provides a new idea for the design and synthesis of efficient catalysts for various applications. [ABSTRACT FROM AUTHOR]

The electrode interface concentration polarization attributed to the contradiction between sluggish mass transfer process and rapid electrochemical reduction kinetics significantly restricts the practical application of Zn anode. Creating a moderate Zn ions transfer and reduction chemistry is essential for durable zinc‐ion batteries. In this work, this trade‐off effect is realized by selecting large‐size 4‐Aminomethyl cyclohexanecarboxylic acid (AMCA) molecule as the electrolyte additive. Intriguingly, AMCA molecules reorganize the Zn2+ solvation structure via the robust coordination with Zn2+ and reconstruct H‐bond networks, giving a pulled desolvation process. Meanwhile, AMCA enlarges the Zn2+ solvation size with a push force, confining the rapid electrochemical reduction kinetics. The balanced chemical environment is maintained via the moderate pull‐push interplay. Besides, AMCA can anchor on zinc surface to create a water‐poor microenvironment, fostering homogeneous Zn (002) deposition and effectively restricting water‐induced side‐reactions. Notably, the Zn||Zn symmetric cell with AMCA operates stably over 167 days at 20 mA cm−2. Moreover, the Zn||VOX full cell employed AMCA ensures outstanding capacity retention of 99.15% after 590 cycles at 2 A g−1, even with low N/P (4.3), lean electrolyte (50 µL mAh−1) and ultrathin Zn foil of 10 µm. This work reveals unique insights into the balanced interfacial chemistry design toward high‐performance zinc batteries. [ABSTRACT FROM AUTHOR]

ABSTRACT The chemistry of plasma–liquid interactions involves a complex interplay of physical and chemical processes at the plasma–liquid interface. These interactions give rise to the generation, transport, and transformation of various reactive species. Since the publication of the Lorenz Roadmap in 2016, significant progress has been made in understanding the interfacial transport and coupled reactions of plasma‐generated species with inorganic and organic compounds. However, critical aspects of plasma–liquid chemistry and mass transfer still require further investigation. This review summarizes recent work on processes at the plasma–liquid interface and the coupled reactions in the liquid phase. We highlight key findings related to the involvement of O atoms, H radicals, solvated electrons, photons, and nitrogen‐derived species at the interface and within the bulk liquid. [ABSTRACT FROM AUTHOR]

The sonohydrothermal (SHT) treatment is an innovative technique allowing the simultaneous coupling of low frequency ultrasound and hydrothermal conditions for the synthesis of materials. The aim of the present work was to investigate, for the first time, the synthesis of zeolite A and its formation mechanism under SHT conditions. The zeolite synthesis was carried out under sonohydrothermal conditions using a specially designed reactor that allows the application of ultrasonic irradiation at 20 kHz in an autoclave-type reactor heated up to 200 °C under autogenous pressure. The conversion kinetics of the amorphous hydrogel to zeolite A and its further conversion to sodalite were studied. Syntheses were performed in the SHT reactor at 80 and 100 °C, varying the synthesis time from 15 minutes to several hours. The required time to obtain fully crystalline zeolite A under sonohydrothermal conditions was only 25 minutes, highlighting a significantly improved crystallization rate compared to silent conditions (a 9.6-fold kinetic gain). In addition, the resulting zeolite A has smaller particles and a more homogeneous particle size distribution than the zeolite synthesized by hydrothermal treatment. These results can be explained by the sonofragmentation of the amorphous gel and the concomitant enhanced mass transfer of the building units at the interface between the crystallite surface and the solution resulting from the acoustic cavitation activity under SHT conditions. Compared to classical hydrothermal heating, a drastic kinetic increase of the transformation of zeolite A into the more stable sodalite phase was also observed under sonohydrothermal conditions. [ABSTRACT FROM AUTHOR]

The current study employs machine learning (ML) techniques to investigate the heat and mass transport of Jeffrey ternary hybrid nanofluid (THNF). Various influential factors, including magnetic field, thermal radiation, viscous dissipation, activation energy, thermophoresis, Brownian motion and surface‐catalysed chemical reactions, are considered in the analysis. The porous moving wedge supports and influences the flow pattern. For thermal enhancement, three different nanoparticles, namely, Ag (silver), CuO (copper oxide) and SWCNT (single − walled carbon nanotubes), diluted in the regular fluid (blood). Initially, the mathematically modelled partial differential equations (PDEs) are solved numerically by the help of the shooting method. The suitable nondimensional similarity transformations are implied to convert the dimensional PDEs to nondimensional ordinary differential equations (ODEs). The reduced dimensionless nonlinear coupled ODEs are solved using ode‐45 in MATLAB. The impact of φAg, φCuO, φSWCNT in Cfx, Nux, Shx, ShP and ShQ is displayed in cone plots. It is found that, on increasing φAg, φCuO, φSWCNT, the heat transfer and mass transfer rate gets enhanced in THNF than the hybrid nanofluid (HNF) and nanofluid (NF). The influence of nondimensional parameters over f″(0), θ′(0), ϕ′(0), G′(0) and H′(0) is displayed in 3D contour plots for THNF and HNF. The radiation parameter (R), Brownian motion parameter (Nb), thermophoresis parameter (Nt) and volume fraction parameters φAg, φCuO, φSWCNT boost the energy transfer rate. Finally, the obtained numerical results are split into training and validation datasets that are used in designing the adaptive neuro‐fuzzy inference system (ANFIS) ML model. Five different ANFIS models are developed with the help of nondimensional parameters affecting f″(0), θ′(0), ϕ′(0), G′(0) and H′(0) to predict the physical quantities of dragging force (Cfx), energy transfer rate (Nux), the rate of mass transport (Shx) and mass fluxes for chemical species P and Q ShP and ShQ, respectively. The training and checking errors attained the convergence less than 2 × 10−4 and 0.2, respectively, for all the five factors. The present ANFIS models have good balance between fitting the training data and generalising to new data, which can make accurate predictions irrespective of variations. The numerical and predicted ANFIS f″(0), θ′(0), ϕ′(0), G′(0) and H′(0) for training data, checking data and results are demonstrated in regression plots. From regression plots, we can observe that the Pearson correlation coefficient attains the positive correlation with R value closer to one. Hence, the developed ANFIS model shows the minimal error in predictions with high degree of accuracy of forecast in THNF flow. [ABSTRACT FROM AUTHOR]

Plaited jersey fabrics are always engineered to enhance the thermal conductivity characteristics, providing thermal equilibrium among the wearer and clothing during hot weather. These can also be architected with higher thermal resistance/heat insulation characteristics and is a crucial area of interest; however there isn't any significant literature reporting this. The study focuses on developing plaited jersey gloves using Thermolite®, acrylic, and wool yarns in alternative main and plaiting configurations for winterwear. Thermal characterizations were conducted to ascertain heat and mass transfer properties, such as fluid transmission and thermal resistance. Infrared (IR) imaging visualized heat retention in terms of temperature gradients. Mechanical characteristics, such as pilling and bursting, were assessed to determine the gloves durability to physical abrasions and stresses. Thermolite® knitted gloves possessed superior heat and mass transfer properties with improved fluid transmission and thermal resistance. Infrared imaging revealed highest body temperature rise of 34.43oC for Thermolite®, and mechanical properties were also found adequate. Fluid transfer (air permeability) was acquired highest for wool samples (1770 mm/sec); however, Thermolite® exhibited 28% lower air permeability than wool, validating its heat retention. Thermolite® knits with the lowest areal density of 226 g/m2 and the smoothest Thermolite® surface had the highest OMMC (overall moisture management capacity) index of 0.46 due to generated capillaries. The statistical analysis of the characterization data indicated the significance (p -value <0.05) of the main and plating yarns, proving the plaiting a solution to achieve desired heat and mass transfer characteristics. [ABSTRACT FROM AUTHOR]

In this paper, an exceptional nitrate reduction to ammonia catalyst is reported, enabled by BO2− anion induction effects combining heterogeneous branching architecture‐driven mass transport enhancement strategies. The implantation of the BO2− anion can inductively enhance the electron cloud density and electron transmission paths of intrinsic catalysts, makes electron more active to improve the conductivity, regulates the adsorption and desorption rates of intermediates by space barrier effect, reduces the binding energy of the electron and 3d orbital of Ni in NiFe(BO2)O(OH), thereby lowing the transform free energy of the determining *NO3 to *HNO3 step. 3D hollow sea urchin lattice heterogeneous branching structure can self‐drive generate differentiated micro convection intervals, which will be beneficial for improving mass transfer dynamics especially localized disturbance mass transfer effect of catalyst for nitrate reduction reaction (NO3RR) catalysis process. Amazingly, the as‐prepared 3D NiFe metaborate oxyhydroxide hollow bionic sea urchins lattice catalyst has a high NH3 rate 6.27mmol·h−1·cm−2 with 98.7% Faradaic efficiency at low ‐0.25V(vs RHE) NO3RR potential. Moreover, the catalytic activity of this highly stable catalyst decreases only slightly over 100 h at ultra‐high 1500mA·cm−2 current. This work breaks through the bottleneck that plagues the performance improvement of non Cu‐based high‐current NO3RR catalysts. [ABSTRACT FROM AUTHOR]

This study aims to assess the efficacy of machine learning models in predicting solute concentration (C) distribution in a membrane separation process, using the input parameters which are spatial coordinates. Computational fluid dynamics (CFD) was employed with machine learning for simulation of process. The models evaluated include Kernel Ridge Regression (KRR), Radius nearest neighbor regression (RNN), K-nearest neighbors (KNN), LASSO, and Multi-Layer Perceptron (MLP). Additionally, Harris Hawks Optimization (HHO) was utilized to fine-tune the hyperparameters of these models. Leading the way is the MLP model, which achieves a remarkable test R2 value of 0.98637 together with very low RMSE and MAE values. Strongness and generalization capacity are shown by its consistent performance on test and training datasets. To conclude, the effectiveness of using machine learning regression methods more especially, KRR, KNN, RNN, LASSO, and MLP in estimating concentration from spatial coordinates was demonstrated in this work. For separation science via membranes where predictive modeling of spatial data is essential, the results offer important new perspectives by developing hybrid model. [ABSTRACT FROM AUTHOR]

Metal halide perovskite single crystals (SCs) have emerged as promising candidates for high‐performance X‐ray detectors. However, mitigating the adverse effects of thermal and interfacial stress during SC growth remains a significant challenge. In this study, the solution growth of high‐quality perovskite SCs using silicone containers through a constant‐temperature autonomous crystallization process is presented. Unlike conventional hard glass vessels, soft silicone containers significantly reduce the negative impact of thermal and interfacial stress on SC growth. Additionally, the microporous nature of silicone containers permits solvent leakage, facilitating autonomous SC growth at constant temperatures. The hydrophilic surface of the silicone further increases the interfacial nucleation barrier and enhances mass transfer, promoting the rapid growth of larger SCs. This multifaceted approach results in MAPbBr3 SCs with an exceptionally low defect density of 2.15×108 cm−3 and an optimal full‐width‐at‐half‐maximum of X‐ray diffraction rocking curves at 19.04 arcsec, consequently leading to an ultralow X‐ray detection limit of 850 pGyair s−1 for the X‐ray detectors. The superior quality of the SCs, combined with a low‐temperature flip‐chip bonding process, enables the integration of the crystals with pixelated arrays on a printed circuit board for both single‐photon detection and low‐dose X‐ray imaging. [ABSTRACT FROM AUTHOR]

High‐efficient and durable electrocatalysts for oxygen reduction and oxygen evolution reaction (ORR/OER) are desirable to Zn‐air batteries (ZABs). However, most of catalysts in powder form with sole active sites remain challenging in achieving the satisfactory bifunctional catalysis and suffer from peeling off during the long‐term operation. Herein, hybrid CoFe active sites are constructed containing nanoalloys (≈10 nm), clusters (< 2 nm), and single atoms on aerophilic carbon fiber membranes as binder‐free air cathodes for ultra‐long‐life ZABs. In particular, the high air‐permeability of membranes (0.2 s) can prevent the active sites from blocking by O2 bubbles and promote the mass transfer. The theoretical and experimental results confirm that the hydrophilic CoFe2O4/CoFeOOH sites reconstructed on the surface of CoFe nanoalloys are mainly responsible for OER. While for single atoms and clusters on nitrogen (N)‐doped carbon matrix, they play a synergetic role in optimizing the adsorption energy to enhance ORR activity. Thus, the as‐prepared catalysts exhibit an ultra‐low ORR/OER potential gap (0.64 V). When further assembled as freestanding air‐electrodes, it exhibits an outstanding cycling lifespan of 1200 and 155 h in liquid‐ and quasi‐solid‐state ZABs respectively, which are fivefold and twofold higher than those of powder‐based cathodes (240/67 h). [ABSTRACT FROM AUTHOR]

The oxidation of ammonium sulfite must be inhibited to improve the economy and cycle performance of the ammonia flue gas desulfurization process. A stirred bubbling reactor was used to investigate the macrokinetics of oxidation inhibition of ammonium sulfite by sodium thiosulfate in wet ammonia desulfurization. The effects of initial SO32−${\rm SO}^{2-}_{3}$ concentration, Na2S2O3 concentration, pH value, gas flow rate, and temperature on the oxidation rate were discussed. The results show that the apparent activation energy of the reaction is 37.3 kJ/mol. The macrokinetics equation of sodium thiosulfate inhibiting sulfite oxidation in the ammonia desulfurization process was established. Combined with the kinetic model, it is inferred that the rate of sodium thiosulfate inhibiting ammonium sulfite oxidation is controlled by the intrinsic chemical reaction. The results can provide a reference for the regeneration of ammonium sulfite in the wet ammonia desulfurization process. [ABSTRACT FROM AUTHOR]

Given the distinct water management requirements in anion-exchange membrane fuel cells (AEMFCs) and proton-exchange membrane fuel cells (PEMFCs), the necessity for tailored flow field redesign and analysis in AEMFCs becomes paramount. In this study, a three-dimensional, two-phase, non-isothermal AEMFC model is constructed to explore the impact of the channel shape of a parallel flow field on the cell performance. The results demonstrate that the channel shape notably influences cell performance at low voltages, and the cell performance follows: inverted trapezoidal > square > triangular > rectangular > trapezoidal > semicircular. A cell with inverted trapezoidal channels achieves a 12.9% increase in peak power density and an 83.4% reduction in current density non-uniformity compared to that with semicircular channels. Analysis of the evaluation criteria indicates that excellent heat transfer performance, superior mass transfer performance, and sufficient water content in the membrane are critical for improving AEMFC performance. • Effect of six channel geometries on the AEMFC performance is investigated. • EMTC, EEC, and inhomogeneity index are used to evaluate the whole performance. • Inverted trapezoidal channels yield the best overall performance. • Triangular channels result in the lowest EEC. [ABSTRACT FROM AUTHOR]

The design of efficient electrocatalysts for ethanol oxidation is essential for commercializing direct ethanol fuel cells (DEFCs). In this strategy, a mesoporous carbon microsphere (MC) was first synthesized by inverting the micro-emulsion technique. The MC@Au/Pd catalyst with a particular core-shell structure was obtained by utilizing mesoporous carbon as a core to load the Au/Pd layer. The novelty of the MC@Au/Pd catalyst with specialized core-shell structures lies not only in the high specific surface area inherited from the carbon core but also in the strong electronic interactions caused by the lattice mismatch between the core (Au) and shell (Pd) atoms. Particularly, electrochemical measures demonstrated that the Au/Pd catalyst exhibits superior catalytic activity toward the ethanol oxidation reaction (EOR) compared with commercial Pd/C catalysts. This is mainly due to the high specific surface area and mesoporous pore size inherited from the core carbon microspheres. In addition, the mesoporous carbon core and Au/Pd shell in the well-organized core-shell catalyst (MC@Au/Pd) influence the catalytic activity for ethanol oxidation by adjusting the electronic structure of Pd. [Display omitted] • A novelty carbon core/Au–Pd shell structure catalyst was first synthesized. • The carbon core provides an abundance of mass transfer channels for EOR. • The well-organized catalyst exhibit enhanced catalytic activity for EOR. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Electrocatalysis technology can effectively promote the hydrodechlorination of chloramphenicol (CAP) to reduce the bio‐toxicity. However, there are still some challenges such as low degradation rate and poor stability. Here, we prepared porous N, O co‐doped carbon supported Pd nanoparticles composites (Pd NPs/NO‐C) for electrocatalytic degradation of CAP. The doping of N and O not only effectively enhanced the interaction between substrate and CAP, promoting the mass transfer process, but also enhanced the anchoring effect on Pd nanoparticles, avoiding the occurrence of aggregation. The prepared composites achieved removal efficiency of CAP over 99% within 1 h, and the rate constant was as high as 6.72 h–1, outperforming previous reported electrocatalysts. Additionally, Pd NPs/NO‐C composites showed a wide range of pH tolerance, excellent ion interference resistance and long‐term stability. Our work unravels the importance of mass transfer processes in solution to electrocatalytic hydrodechlorination and provides new research ideas for catalysts design. [ABSTRACT FROM AUTHOR]

Currently, NiFe-LDH exhibits an excellent oxygen evolution reaction (OER) due to the interaction of the two metal elements on the layered double hydroxide (LDH) platform. However, such interaction is still insufficient to compensate for its poor electrical conductivity, limited number of active sites and sluggish dynamics. Herein, a feasible two-step hydrothermal strategy that involves coupling low-conductivity NiFe-LDH with 3D porous graphene aerogel (GA) is proposed. The optimized NiFe-LDH/GA (1:1) produced possesses a 257 mV (10 mA cm−2) overpotential and could operate stably for 56 h in an OER. Our investigation demonstrates that the NiFe-LDH/GA has a three-dimensional mesoporous structure, and that there is synergistic interaction between LDH and GA and interfacial reconstruction of NiOOH. Such an interface synergistic coupling effect promotes fast mass transfer and facilitates OER kinetics, and this work offers new insights into designing efficient and stable GA-based electrocatalysts. [ABSTRACT FROM AUTHOR]

The study of the blood flow through arterial walls is an important subject due to different chemical reactions and magnetohydrodynamic having an impact on the arterial walls during the treatment of cancer, malignant tumors, drug targeting and endoscopy. So, this paper aims to present a comprehensive investigation of the blood bioconvective flow of Carreau–Yasuda (C–Y) nanofluids in an arterial. Variable velocity conditions near the walls are considered. The flow domain is filled by a porous medium and a time-dependent magnetic field is assumed. The impacts of an exponential chemical reaction are considered and the viscous dissipation in the case of the C–Y model is formulated and examined. The fully implicit finite difference method is applied to solve the dimensionless governing system. The case of the shear thinning (n = 0.5) and shear thickening (n = 1.5) are analyzed for the variations of the governing parameters such as Weissenberg (0.001 ≤We ≤ 0.1) and parameter of the porous medium (0 ≤ β ≤ 2). The major outcomes revealed that the friction coefficient is improved as the C–Y parameter is raised. Also, values of heat and mass transfer are higher in the case of the shear thinning compared to the shear thickening. [ABSTRACT FROM AUTHOR]

The notion of spontaneous and persistent energy generation from omnipresent atmospheric moisture presents an alluring prospect in the realm of next‐generation energy sources. Here, an ultra‐durable and all‐weather energy generator (UAEG) predicated on interface‐induced proton migration derived from enhanced proton dissociation by charge transfer and ion occupation is reported, which reduces the diffusion barrier of protons in chromatogram‐like mass transfer by avoiding the rebinding of dissociated protons with charged polyelectrolyte chains, thus leading to efficient and continuous proton migration through heterogeneously hygroscopic interface and delivering ultra‐durable direct‐current output. Deep insight into underlying mechanisms is demonstrated by theoretical calculations and in situ investigations toward molecular interactions and charge distribution. A UAEG unit with 4 cm2 in size can generate an impressive electric output (0.88 V and 37.58 µA) across extensive relative humidity (10–90%) and ambient temperature (−30–50 ˚C), capable of generating energy in all‐weather conditions (e.g., sunny, cloudy, overcast, and rainy) regardless of day and night. Importantly, it is the first time that a commercial electronic is continuously driven for over 200 days in all‐weather conditions just depending on ambient moisture. This work provides a novel perspective for the development of ultra‐durable and all‐weather moisture‐enabled energy generators. [ABSTRACT FROM AUTHOR]

One of the questions still remaining regarding emulsion polymerization is the issue of mass transfer versus reaction limitation since, by its nature, emulsion polymerization requires monomer transport across an aqueous phase. This question is brought into focus lately by the growing use of miniemulsion polymerization in which the monomer transport step is much less important. This paper will explore the possible rate of monomer transport via collision and ratio this to the maximum rate of polymerization using the Damkohler analysis formality. Results indicate that systems relying on monomer transport by collision will be almost universally monomer‐transport‐limited, thus exhibiting lower‐than‐expected rates of polymerizations. [ABSTRACT FROM AUTHOR]

In the case of CO2 thermal‐catalytic hydrogenation, highly selective olefin generation and subsequent olefin secondary reactions to fuel hydrocarbons in an ultra‐short residence time is a huge challenge, especially under industrially feasible conditions. Here, we report a pioneering synthetic process that achieves selective production of high‐volume commercial gasoline with the assistance of fast response mechanism. In situ experiments and DFT calculations demonstrate that the designed NaFeGaZr presents exceptional carbiding prowess, and swiftly forms carbides even at extremely brief gas residence times, facilitating olefin production. The created successive hollow zeolite HZSM‐5 further reinforces aromatization of olefin diffused from NaFeGaZr via optimized mass transfer in the hollow channel of zeolite. Benefiting from its rapid response mechanism within the multifunctional catalytic system, this catalyst effectively prevents the excessive hydrogenation of intermediates and controls the swift conversion of intermediates into aromatics, even in high‐throughput settings. This enables a rapid one‐step synthesis of high‐quality gasoline‐range hydrocarbons without any post‐treatment, with high commercial product compatibility and space‐time yield up to 0.9 kggasoline ⋅ kgcat−1 ⋅ h−1. These findings from the current work can provide a shed for the preparation of efficient catalysts and in‐depth understanding of C1 catalysis in industrial level. [ABSTRACT FROM AUTHOR]

Solution‐processed perovskite films generally possess small grain sizes and high density of grain boundaries, which intensify non‐radiative recombination of carriers and limit the power conversion efficiency (PCE) of solar cells. In this study, we report the room‐temperature ripening enabled by the synergy of hygroscopic salts and moisture in air for efficient hole‐conductor‐free printable mesoscopic perovskite solar cells (p‐MPSCs). Treating perovskite films with proper hygroscopic salts in damp air induces obvious secondary recrystallization, which coarsens the grains size from hundreds of nanometers to several micrometers. It's proposed that the hygroscopic salt at grain boundaries could absorb moisture and form a complex which could not only serve as mass transfer channel but also assist in the dissolution of perovskite grains. This activates mass transfer between small grains and large grains since they possess different solubilities, and thus ripens the perovskite film. Consequently, p‐MPSCs treated with the hygroscopic salt of NH4SCN show an improved power conversion efficiency of 20.13 % from 17.94 %, and maintain >98 % of the initial efficiency under maximum power point tracking at 55±5 °C for 350 hours. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction technology offers an effective way to convert CO2 into valuable chemicals and fuels, presenting a sustainable solution for carbon emissions. Current electrocatalytic CO2 reduction technologies encounter significant issues such as salt precipitation and hydrogen evolution, which prevent energy conversion efficiency, selectivity, current density, and stability from simultaneously meeting industrial standards. In recent years, researchers have discovered that increasing the CO2 pressure on the gas supply could enhance the coverage of the catalyst and activate more CO2 reduction reaction sites on the catalyst surface, which provides a practical and effective approach for optimizing the energy conversion and mass transfer. In this review, we provide a comprehensive review of the development history and current status of high-pressure CO2 electrocatalytic reduction technology, focusing on its reaction devices, catalytic performance, and reaction mechanisms. Furthermore, we summarize and offer insights into the most promising research avenues to propel the field forward. Highlights: 1. A briefly discussion on the challenges faced by CO2 electrochemical reduction. 2. The state-of-the-art progress of the high-pressure CO2 electrochemical reduction for chemical synthesis is summarized. 3. The bottlenecks of current high-pressure CO2 electrochemical reduction technology are highlighted and potential optimization strategies are proposed. [ABSTRACT FROM AUTHOR]

Poly ether ether ketone (PEEK) is a premier engineering plastic, which has gained considerable attention in recent years. Our prior research investigated crystallization template techniques and pore formation mechanisms within the PEEK/poly (ether imide) system, paving the way for the development of hierarchically porous membranes (HPMs). Compared to single‐porous membranes, HPMs demonstrate enhanced flux and high mass transfer efficiency simultaneously, effectively mitigating the trade‐off effects. In this study, we focused on fabricating PEEK HPMs through precise manipulation of a polymer ternary blend system. The meticulous tuning enables intricate control of the hierarchical pore morphology of PEEK at two distinct scales. The finite element simulations not only underscored the crucial role of hierarchical pores in bolstering separation efficiency, but also exhibited strong concordance with the experimental findings. This study provides guidance for future optimization of HPMs with superior separation performance. [ABSTRACT FROM AUTHOR]

The addition of polar functional groups to porous structures is an effective strategy for increasing the ability of metal–organic frameworks (MOFs) to capture CO2 by enhancing interactions between the dipoles of the polar functional groups and the quadrupoles of CO2. However, the potential of MOFs with polar functional groups to activate CO2 has not been investigated in the context of CO2 electrolysis. In this study, we report a mixed‐ligand strategy to incorporate various functional groups in the MOFs. We found that substituents with strong polarity led to increased catalytic performance of electrochemical CO2 reduction for these polarized MOFs. Both experimental and theoretical evidence indicates that the presence of polar functional groups induces a charge redistribution in the micropores of MOFs. We have shown that higher electron densities of sp2‐carbon atoms in benzimidazolate ligands reduces the energy barrier to generate *COOH, which is simultaneously controlled by the mass transfer of CO2. Our research offers an effective method of disrupting local electron neutrality in the pores of electrocatalysts/supports to activate CO2 under electrochemical conditions. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) occurs at the nanoscale interface of the electrode‐electrolyte. Therefore, tailoring the interfacial properties in the interface microenvironment provides a powerful strategy to optimise the activity and selectivity of electrocatalysts towards the desired products. Here, the microenvironment at the electrode‐electrolyte interface of the flow‐through Ag‐based hollow fibre gas diffusion electrode (Ag HFGDE) is modulated by introducing surfactant cetyltrimethylammonium bromide (CTAB) as the electrolyte additive. The porous hollow fibre configuration and gas penetration mode facilitate the CO2 mass transfer and the formation of the triple‐phase interface. Through the ordered arrangement of hydrophobic long‐alkyl chains, CTAB molecules at the electrode/electrolyte interface promoted CO2 penetration to active sites and repelled water to reduce the activity of competitive hydrogen evolution reaction (HER). By applying CTAB‐containing catholyte, Ag HFGDE achieved a high CO Faradaic efficiency (FE) of over 95 % in a wide potential range and double the partial current density of CO. The enhancement of CO selectivity and suppression of hydrogen was attributed to the improvement of charge transfer and the CO2/H2O ratio enhancement. These findings highlight the importance of adjusting the local microenvironment to enhance the reaction kinetics and product selectivity in the electrochemical CO2 reduction reaction CO2RR. [ABSTRACT FROM AUTHOR]

Electroreduction of oxalic acid (OX) to glyoxylic acid (GO) is an extremely important and promising application in organic electrosynthesis. Pb cathodes, which exhibits good selectivity, need to be replace due to the severe deactivation and harmful to the environment. Herein, self‐doped titanium dioxide nanotube arrays (H‐TiO2NTs‐2) are synthesized as an alternative cathode for OX electroreduction to GO. Benefiting from two‐step anodization, the synthesized nanotube arrays are highly ordered with oriented openings. The ordered structure promotes the mass transfer of both OX and GO to ensure efficiently providing OX reactants for the diffusion‐controlled OX electroreduction and removal of GO products from the electrode to prevent the over‐reduction to glycolic acid. Additionally, the electroreduction treatment introduces more Ti3+ active sites and modulates the conduction band position of H‐TiO2NTs‐2, thereby enhancing the reduction driving force. Owing to the unique structural advantages, the Faraday efficiency of generating GO from OX reaches up to 81.3 % in an oxalic acid saturated electrolyte at 20 °C with a current density of 1500 A m−2. This designed H‐TiO2NTs‐2 holds broad application prospects in OX electroreduction. [ABSTRACT FROM AUTHOR]

The paper explores the 3D stationary vortex structure of turbulent airflow near the dead-end face of a blind heading, ventilated via a forcing ventilation system. Despite its significance in blind heading ventilation, previous studies primarily focused on temporal dynamics of harmful impurities, overlooking flow structure details crucial for mass transfer processes. Our study delves into the ventilation flow structure across diverse parameters of the auxiliary ventilation system. Alongside standard flow visualization tools, we introduce three dimensionless indicators to comprehensively characterize flow structure, facilitating analysis of its variations with parameter changes and quantitative evaluation of system efficiency. Analysis revealed the formation of a single large-scale vortex within the entire range of considered ventilation system parameters in the heading. This vortex induces a significant increase in air circulation, approximately 2.5–3.5 times greater than airflow emerging from the ventilation duct's end, thus intensifying mass transfer processes within the heading. We found that ventilation efficiency of the dead-end face zone in a blind heading with a 29.2 m² cross-section decreases linearly with increasing distance between the ventilation duct's end and the dead-end face. However, compensating for this distance by increasing duct velocity is feasible, bearing significant implications for mine ventilation safety, particularly in ventilating blind headings with distant ducts from the dead-end face. [ABSTRACT FROM AUTHOR]

This study examines the stability of double-diffusive convection in a Kuvshiniski viscoelastic nanofluid, in which the fluid is affected by two fields (such as temperature and salinity) that influence its density. The classical Fick’s law, which assumes an immediate response of temperature to the heat flux gradient, is not entirely correct because it suggests an instantaneous reaction at all points, which is not entirely accurate since information propagates at a finite speed. This shortcoming of Fick’s law leads us to consider the Maxwell–Cattaneo effect (MC effect). Thus, our research focuses on Maxwell–Cattaneo double-diffusive convection in a horizontal layer of a porous medium saturated with viscoelastic nanofluid. Here, the fluid’s small dimensions result in its relaxation time being comparable to its thermal diffusion time, necessitating the use of the Maxwell–Cattaneo relationship. The behavior of viscoelastic nanofluids is described by a constitutive equation of the Kuvshiniski kind, and for the porous medium, Brinkman–Darcy model is considered. The nanofluid model includes the effects of Brownian diffusion and thermophoresis, with the assumption that the flux of the nanoparticle volume fraction is zero at the isothermal boundaries. The framework of linear and nonlinear stability theory leads the analysis. By applying linear stability theory with the help of normal mode technique, the conditions for the occurrence of both stationary and oscillatory convective motions are found in terms of a critical thermal Rayleigh number. The Kuvshiniski viscoelastic fluid exhibits Newtonian behavior in a state of stationary convection. We have discussed two cases for oscillatory convection that are when (i) Maxwell–Cattaneo coefficient for temperature (C T ) = 0 and (ii) Maxwell–Cattaneo coefficient for salinity (C C ) = 0. Convective heat and mass transfers are determined using a weakly nonlinear stability analysis. The effects of various factors on oscillatory and stationary states as well as the mass and heat transport are depicted graphically. It is found that with increase in the value of Kuvshiniski parameter F, thermal Rayleigh number Ra also increases for both cases C T = 0 and C C = 0. Ra drops with increasing values of modified diffusivity ratio N A and thermosolutal Lewis number Ls for both stationary as well as oscillatory convection. With increase in the value of Darcy number Da, an interesting pattern can be seen. For stationary convection, Ra increases with Da, but it has reverse effect on oscillatory convection (for both the cases). Streamlines, isotherms, and isohalines are also examined. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis (AWE) holds considerable promise for large-scale hydrogen production. Decreasing energy input and improving efficiency are inevitable in its further commercial development. As one of the critical factors for reducing energy consumption, flow channel design on bipolar plates cannot be ignored. This study utilizes a three-dimensional model for alkaline electrolyzer that couples electrochemical reactions with mass and heat transfer to approximate the real physical process and achieve reliable convergence. Integrating diverse turbulence units tailored to different local flow demands, an advanced Partitioned Point Flow Channel (PPFC) structure is proposed aiming at optimizing electrolyte flow distribution. Results reveal that PPFC's unique combination of turbulence units promotes lateral flow and electrolyte mass transfer rate, increasing electrolyte flow uniformity and hydrogen removal efficiency by 17.5% and 24.4%, respectively. Further comparative analysis with traditional designs shows an average diaphragm temperature drop of 4 K and a current density increase of 10.7% at a cell voltage of 2 V. These results indicate that PPFC offers significant advantages in reducing energy loss in electrolyzer. • 3-D AWE model couples electrochemical reaction with mass and heat transfer is built. • Advanced PPFC integrates different turbulence units for diverse local flow demands. • PPFC improves flow uniformity by 17.5% and hydrogen removal efficiency by 24.4%. • PPFC reduces average temperature by 4 K and increases current density by 10.7%. [ABSTRACT FROM AUTHOR]

This paper investigated the heat transfer phenomenon and enhancement mechanism in MgH 2 based hydrogen storage reactors, aiming to optimize the heat and mass transfer resistance and reaction kinetics issues encountered in practical applications of the hydrogen storage materials. The powdered MgH 2 hydrogen storage material and its compacted disks were prepared to study the thermophysical properties and hydrogen absorption/desorption characteristics. For the disk prepared by composite 5 wt% EG under a compression pressure of 100 MPa, its axial and radial thermal conductivity can be as high as 2.53 and 2.03 W/(m·K), respectively, and the average hydrogen absorption rate within 1000 s is 17.2% faster than that of the powder material when applied in reactors. To gain a better understanding of the influence of the material properties, and operating conditions on the heat transfer and reaction performance inside the reactor, mathematical models for the heat and mass transfer and reaction processes of the reactor were established. Simulation results revealed the coupling mechanism of heat transfer and reaction within the storage reactor, and showed that the increased thermal conductivity and hydrogen absorption pressure can further accelerate absorption process. When the thermal conductivity increases from 2 to 10 W/(m·K) and the absorption pressure increases from 1 to 1.8 MPa, the average hydrogen absorption rate can increase by 79.4% and 42.2%, respectively. • Ball milled magnesium hydride powder showed high reactivity. • Compacted disks showed high thermal conductivity and H 2 storage capacity. • An experimental device was built for testing H 2 ab/desorption of reactors. • Coupling mechanism between transfer and reaction inside reactors was revealed. • Higher H 2 pressure is profit to enhance heat transfer and absorption reaction. [ABSTRACT FROM AUTHOR]

The single-atom dispersed active sites and the thicker catalytic layer of metal-nitrogen-carbon (M-N-C) electrocatalysts based membrane electrode assembly (MEA) exhibit notable distinctions from Pt-based MEA, necessitating targeted optimization. This study systematically investigates the influence of compression on both structure and performance of the M-N-C electrocatalysts based MEA. Four compression ratios, ranging from 11.5% to 39.3%, were examined across diverse operational conditions. The variations in impedance across different electrochemical regions are observed, resulting from the superposition of distinct impedance components. It is found that the insufficient compression leads to higher porosity and the formation of cracks between catalytic layer and membrane, adversely impacting internal resistance and proton transport. Increasing compression first acts the catalytic layer, and then gradually acts on the interface, membrane and gas diffusion layer, thereby reducing internal resistance, charge transfer resistances, albeit at the expense of heightened mass transfer resistance. Among these factors, the influence of internal resistance affects significance to total performance. Furthermore, compression influenced mass transfer differently in various layers. For the catalyst layer, the effect was uniform and sustained, while for the gas diffusion layer, it initially remained constant and then experienced a sudden deterioration over a certain extent. Optimal MEA performance is achieved when the compression ratio attains 40 %, which 2.1 times higher than the low compression MEA. This finding emphasizes the necessity for higher compression on M-N-C electrocatalysts based MEA compared to Pt-based MEA. [Display omitted] • The optimal compression ratio of 40 % is explored for M-N-C catalyst based MEA. • Compression facilitates the cell dynamics process. • The internal resistance dominates the cell performance. • The differential effect of compression on CL and GDL is found. [ABSTRACT FROM AUTHOR]

The utilization of liquid organic hydrogen carrier (LOHC) based on acetophenone has been considered a promising approach for high energy density hydrogen storage, but its industrial application is limited by the low reaction and mass transfer rates observed in conventional reactors. Microreactors have the potential to promote hydrogen storage technology, and, in this study, we propose a tubular reactor coupled with a gas/liquid microdispersion module. Via generating microbubbles prior to the flow of gas and liquid reactants in the tubular reactor, our designed reactor facilitates enhanced gas/liquid interaction mass transfer, thereby improving hydrogenation reaction characteristics. To evaluate the performance of this intensified trickle bed reactor, we investigated the hydrogenation of acetophenone (AP) to 1-phenylethanolis. The results demonstrate that compared to traditional trickle bed reactors, the designed hydrogenation reactor exhibits superior performance under pressures below 2 MPa, with an absence of byproducts, increased conversion and selectivity of AP, and an achieved hydrogen storage rate reaching 0.095 mol H 2 / g Pd / min. [Display omitted] • An intensified hydrogenation reactor was proposed for efficient hydrogen storage. • A gas/liquid micro-dispersion system has been incorporated into a tubular reactor. • The reaction performance of reactors is evaluated using acetophenone hydrogenation. • The intensified reactor shows a nearly twofold increase in hydrogen storage rate. [ABSTRACT FROM AUTHOR]

This study investigates the impact of porosity distribution on the hydrogen storage performance of metal hydride (MH) reactors through numerical simulations. Firstly, the effects of different porosities on heat and mass transfer characteristics during hydrogen adsorption and desorption processes were analyzed. The results indicate that with increasing porosity, the hydrogen storage and release rates improved, but the hydrogen storage density decreased. To enhance reactor performance while maintaining hydrogen storage density, the bed porosity distribution was optimized. The optimization results showed that the hydrogen storage and release times of the MH reactor were reduced by 57.15% and 29.70%, respectively, at the same hydrogen storage density. Moreover, the optimized structure exhibited excellent hydrogen storage and release performance under different operating conditions, demonstrating its potential advantages in practical applications. • MH bed porosity significantly affects heat and mass transfer performance. • Bed porosity distribution is optimized by Monte Carlo algorithm. • Hydrogen storage and release times are reduced by 57.15% and 29.7%. • Optimized structure shows superior performance under various conditions. [ABSTRACT FROM AUTHOR]

In recent days, entropy generation has attracted the attention of several researchers due to its applications in manufacturing electronic devices, heat exchangers, conservation of energy, and generation of power. Further, activation energy is an essential requirement in automobile and chemical industries, nuclear reactors, and so on. This paper investigation aims to examine the entropy generation and the mass and energy transfer in the magneto-hydro dynamic movement of convective Carreau-Yasuda nano liquid past a porous stretching sheet with the consequences of activation energy, energy source, and binary chemical reaction. Also, the analysis of the impact of viscous and Joule dissipation in the presence of suction/injection into the Buongiorno model is an essential objective of this study. By introducing a similarity variable, the partial differential equations are altered into a system of ordinary differential equations. Numerical solutions to the modified equations are determined by utilizing a BVP5C MATLAB package. The findings are presented visually for several relevant flow characteristics and explained carefully. The thermophoresis parameter and activation energy parameter optimize the concentration of nanoparticles. These outcomes further indicate that as the larger Brinkmann and permeability parameters the entropy generation is broadened. It is discovered that an augmentation in thermal and solutal Grashof numbers is associated with greater velocity distribution. [ABSTRACT FROM AUTHOR]

This novel study unfolds the heat and mass transfer investigation of Williamson nanofluid (WNF) through a porous medium past a stretching plate, along with considering heat generation/absorption. Nanoparticles hold significant significance in thermal engineering, industrial operations, and biomedical advancements, contributing to enhanced heat transfer, cooling mechanisms, thermal extrusion processes, and applications in cancer treatment, particularly in addressing brain tumors. The coupled ordinary differential equations (ODEs) are gained from governing partial differential equations (PDEs) by applying sufficient transformations. Then the ODEs of a nonlinear nature, along with boundary conditions, are solved through bvp4c, a built-in MATLAB program. A good agreement has been found in comparing the present study with already published papers. Numerical values for skin friction, mass transfer, and heat transfer are shown through a table against involved physical parameters, especially for both injection (S < 0) and suction (S > 0) cases, by varying the values of unsteadiness parameter A and Weissenberg number W e . The effects of the physical parameters on velocity, temperature, and mass profile are graphically depicted and illustrated minutely. It is noted that both the magnetic and Williamson parameters cause the thickness of the boundary layer to be reduced. It can be deduced from these findings that the rate of heat transfer over the surface of the plate decreases as the unsteadiness parameter increases. Furthermore, it is observed that an increase in the parameters of thermophoresis and Brownian motion leads to a higher temperature of the nanofluid. [ABSTRACT FROM AUTHOR]

The article examines the thermohydrodynamics of rarefied Poiseuille flow in a finite length channel, emphasizing the impact of dilatation and non-isochoric effects. Variations in pressure-driven and acceleration-driven Poiseuille flows are discussed, with a focus on the saturation of mass flow rate at high Knudsen numbers in pressure-driven flow. The study highlights the significance of dilatation in explaining differences in hydrodynamic fields, rheology, and flow-induced heat transfer between the two flows, as well as the implementation of boundary conditions and averaging procedures in the DSMC method. The research suggests that further exploration is needed to understand the implications of dilatation in various flow scenarios and discusses the challenges in solving the Boltzmann equation using the DSMC method. [Extracted from the article]

An urgent challenge to the development of rechargeable Zn–air batteries (RZABs) is the highly active, durable, and low‐cost catalysts for oxygen reduction reaction and oxygen evolution reaction (ORR and OER). Herein, a carbon‐based monolithic catalyst is designed via anchoring P‐modified MnCo2O4 inverse spinel nanoparticles on biomass‐derived carbon (P‐MnCo2O4@PWC). The introduction of surface P atoms regulates the electronic structures and valences of metal atoms by adjusting the coordination fields by (P‐O)δ– and Metal‐P. The optimization of the adsorption behavior of key intermediates facilitates the activation and conversion of reaction species. The monolithic structure is beneficial to the construction of a three‐phase interface for efficient mass transfer and high electrical conductivity. The P‐MnCo2O4@PWC catalyst displays outstanding bifunctional catalytic properties with a thin ΔE (the difference between the OER potential at 10 mA cm–2 and the ORR halfwave potential) of 0.66 V. The RZAB with P‐MnCo2O4@PWC as cathode delivers an exceptional peak power density (160 mW cm–2) and remarkable cycle life (over 1200 cycles), overcoming those with noble metal counterparts. This research provides a promising general surface‐phosphorization way to the design of carbon electrocatalysts and the high‐value utilization of biomass. [ABSTRACT FROM AUTHOR]

This study investigates an oil/water two-phase system to assess the potential efficacy of a novel passive mixer in enhancing the liquid-liquid interfacial area within a micro-channel contactor. In this system, two fluids are introduced into a microchannel with a diameter of 800 μm and a length of 20 cm, which is equipped with a stainless-steel helical wire measuring 250 μm in diameter. Throughout the experiments, both fluids are supplied at equal flow rates, and the dominant forces, including attachment and detachment forces, are examined. The results reveal a critical Weber number of 3.8 × 10−³, at which the first detachment occurs. A comparison between microchannels with and without the passive micromixer demonstrates that greater slug breakup occurs in the system incorporating the helical wire micromixer. This innovative configuration results in a significant reduction in slug/droplet size compared to a microchannel without a barrier, decreasing from approximately 600 μm to 390 μm at a flow rate of 0.8 mL/min. Additionally, a flow map is presented, illustrating three distinct flow regimes: flow contains long slug, Slug-droplet flow, and droplet flow regimes, with the droplet flow regime covering the largest area. The findings indicate that the implementation of this innovative passive mixer substantially increases the interfacial area, providing significant advantages for mass transfer applications. [ABSTRACT FROM AUTHOR]

Microporous zeolite is commonly employed as the catalyst for selective catalytic reduction of NOx using NH3 as reducing agent (NH3‐SCR) because of its strong acidity and exceptional hydrothermal stability. However, the channel of microporous zeolite limits mass transfer under low temperature. Hierarchical porous molecular sieves can overcome the above imperfections. Hierarchical pore (microporous/mesoporous/macroporous) ZSM‐5 molecular sieves were prepared using polystyrene(PS) microspheres with different particle size as the hard templates and then the ion exchange method was utilized to introduce the active components Ce, Cu, and La. In addition, the effect of PS microspheres with different size and H2O+SO2 on denitrification performance was also investigated. The results exhibited that the specific surface area of the hierarchical pore ZSM‐5 was the smallest when the size of polystyrene microspheres was the largest. The NOx conversion of all supported hierarchical porous catalysts is more than that of supported microporous ZSM‐5 catalyst in the low temperature (200 °C), which was because that the presence of the mesopores favored diffusion‐control in the low temperature, expediting the reactant transport. Furthermore, the supported hierarchical pore ZSM‐5 catalyst exhibited excellent denitrification performance in a wide temperature range of 250–500 °C (the conversion of NOx exceeded 80 % and the N2 selectivity was approaching 100 %). More importantly, the supported hierarchical pore ZSM‐5 catalyst demonstrated notably superior water and SO2 resistance in comparison to the supported micropore ZSM‐5 catalyst. [ABSTRACT FROM AUTHOR]

Polymer electrolyte membrane fuel cells, which have already been put into practical use in some areas, are expected to become widespread to realize a next-generation sustainable energy society. However, it faces several challenges to its performance and durability. The challenges include Pt particle agglomeration, catalyst degradation, low Pt mass catalyst loading, support material corrosion and mass transport resistance, which lead to reduced catalytic activity, limited fuel cell efficiency and decreased durability. Researchers have investigated multiple strategies to overcome these challenges, such as catalyst alloying, support optimization, advanced synthesis techniques, surface modification, and improved water and gas management. This work focuses on the aforementioned challenges associated with Pt nanocatalysts, catalyst supports, and ionomers in polymer electrolyte fuel cells, offering a comprehensive review and discussion of these issues and the corresponding mitigation approaches. In summation, it is suggested that by addressing these challenges, we can pave the way for developing more efficient, durable, and commercially viable fuel cell systems. • Pt catalyst, low loading, and mass resistance impact the PEM fuel cell. • Pt agglomeration reduces surface area and impairs fuel cell performance. • Catalyst support corrosion is a challenge when optimizing for cell efficiency. • Scalable Pt catalyst manufacturing is crucial; explore cost-effective methods. • Excess ionomer hinders mass transfer, impacting fuel cell efficiency. [ABSTRACT FROM AUTHOR]

Current challenges in air-breathing microfluidic fuel cells (AMFCs) technology include insufficient fuel transfer and unsatisfactory power density. To address these issues, this study develops a three-dimensional computational model to optimize the performance of AMFC with a discrete-hole anode. This model reveals that the "petal-shaped" non-uniform fuel distribution is due to the shearing and dilution effects of the electrolyte. Additionally, discrete-hole structures such as size have a slight influence on fuel transport and current production, with performance deviations under 1.6%. Significant improvements are achieved by reducing the electrolyte flow rate and electrode length. Transitioning from a single cell with a long anode to a series/parallel stack of cells with short electrodes significantly boosts net power output and fuel utilization. Under optimal conditions, a maximum power density of 349.9 mW cm−3 and an output of 19.2 mW are obtained. This research provides valuable insights into fuel transport mechanisms and power enhancement strategies in the AMFCs, guiding the future design and optimization of microfluidic reactors for energy conversion. [Display omitted] • A three-dimensional computational model for air-breathing microfluidic fuel cells with discrete-hole anode is developed. • The fuel concentration exhibits a "petal-shaped" non-uniform distribution. • Discrete-hole structures slightly influence fuel transport and current production. • A maximum power density of 349.9 mW cm−3 and an output of 19.2 mW are achieved. [ABSTRACT FROM AUTHOR]

The validity of the Oberbeck–Boussinesq (OB) approximation in Rayleigh–Bénard (RB) convection is studied using the Gray & Giorgini (Intl J. Heat Mass Transfer , vol. 19, 1976, pp. 545–551) criterion that requires that the residuals, i.e. the terms that distinguish the full governing equations from their OB approximations, are kept below a certain small threshold $\hat {\sigma }$. This gives constraints on the temperature and pressure variations of the fluid properties (density, absolute viscosity, specific heat at constant pressure $c_p$ , thermal expansion coefficient and thermal conductivity) and on the magnitudes of the pressure work and viscous dissipation terms in the heat equation, which all can be formulated as bounds regarding the maximum temperature difference in the system, $\varDelta$ , and the container height, $L$. Thus for any given fluid and $\hat {\sigma }$ , one can calculate the OB-validity region (in terms of $\varDelta$ and $L$) and also the maximum achievable Rayleigh number ${{Ra}}_{max,\hat {\sigma }}$ , and we did so for fluids water, air, helium and pressurized SF $_6$ at room temperature, and cryogenic helium, for $\hat {\sigma }=5\,\%$ , $10\,\%$ and $20\,\%$. For the most popular fluids in high- ${{Ra}}$ RB measurements, which are cryogenic helium and pressurized SF $_6$ , we have identified the most critical residual, which is associated with the temperature dependence of $c_p$. Our direct numerical simulations (DNS) showed, however, that even when the values of $c_p$ can differ almost twice within the convection cell, this feature alone cannot explain a sudden and strong enhancement in the heat transport in the system, compared with its OB analogue. [ABSTRACT FROM AUTHOR]

Glass vials with silicone stoppers are commonly used for pharmaceutical freeze-drying. Vials are partially stoppered before lyophilization to prevent contamination but introduce resistance to vapor flow through a small aperture. A Computational Fluid Dynamics (CFD) analysis using Comsol Multiphysics assessed mass transport resistance with different stopper geometries. Three case studies, representing conventional batch freeze-drying, continuous freeze-drying, and low-fill-volume drug products, were simulated, comparing stopper effects on process variables. While stoppers minimally influenced conventional freeze-drying, they significantly affected low-fill volume formulations. The study emphasizes the impact of stopper positioning on batch heterogeneity, especially when monitoring vials with thermocouples to infer product resistance. Heightened attention is essential in this regard. [ABSTRACT FROM AUTHOR]

Biochar derived from biomass resources as a carrier to load SnO2 for electroreduction of CO2 not only can benefit carbon emissions, but it also can achieve waste utilization. However, the weak CO2 mass transfer and conductivity ability of SnO2/biochar limits its applications to such eCO2RR processes. This study focused on modifying SnO2/biochar with amino groups and investigated the effects of positioning of amino groups on the catalyst's physicochemical properties and electrocatalytic behaviors. Elemental analysis revealed that anchoring amino groups on biochar (SnO2/C-NHx) is advantageous for increasing amounts of amino groups attached, thereby enhancing biochar adsorption energy and subsequently increasing the loading of Sn. The CO2 adsorption curve indicated that amino groups anchored on biochar facilitate CO2 adsorption due to high specific surface area of biochar. X-ray photoelectron spectroscopy showed that amino groups anchored on SnO2 (NHx-SnO2/C) resulted in highly electron-rich centers on Sn, which promoted electron transfer between the catalyst and CO2. Electrochemical tests demonstrated the improved performance of amino-modified SnO2/biochar. SnO2/C-NHx exhibited enhanced Faraday efficiency, whereas NHx-SnO2/C showed higher current density. The disparity in electrochemical performance can be mainly attributed to the different selectivity towards rate-controlling steps of electron transfer and mass transfer induced by the various positions of amino groups anchoring. [ABSTRACT FROM AUTHOR]