Fuel Oxidation Reaction Research Articles

Development of Anode Catalysts for Anion Exchange Membrane Fuel Cells Operating with Both H2 and Liquid Fuels

In 2016, for the first time a polymer electrolyte fuel cell with no Pt based electrocatalysts delivered more than 0.5 W cm-2 of peak power density from H2 and air (CO2 free).[1,2] This was achieved with an Ag oxygen reduction (ORR) cathode and a Pd-CeO2 hydrogen oxidation reaction (HOR) anodic electrocatalyst. The hydrogen oxidation (HOR) reaction under alkaline conditions is a kinetically slow process even with Pt group metals. In this presentation, we discuss our strategies to improve the alkaline HOR activity of transition metal nanoparticles. For example, through engineering strong interactions with transition-metal oxides such as CeO2 incorporated in the carbon based catalyst supports.[3] Another strategy involves utilizing novel carbon based supports such as onion like carbon (OLC). The combination of CeO2 and OLC in Pd–CeO2/OLC induces around 7% defects and modifies the electronic structure of the Pd-OLC interface, significantly improving the electrical conductivity due to enhanced charge redistribution, corroborated by density functional theory (DFT) calculations.[4] Alloying of Pd with oxophilic elements like Au and Cu also enhances fuel oxidation reactions by facilitating adsorption of OH- on the catalyst surface. Peak power densities of up to 2 W cm-2 are obtained when Pd-CeO2 is incorporated in AEMFC testing.[5] Regarding liquid fuels, we are currently developing a 100 W fuel cell system using anion exchange membranes and Pd alloy nanoparticle catalysts. The fuel cell stack will be fed with aqueous solutions of potassium formate produced from combining renewable energy and waste industrial CO2. This work is funded by EU Horizon Europe (Project FRESH - GA 101069605) [6].

Facile synthesis of green graphite-based (Ni/Cu/N) MOF composite for a methanol oxidation reaction

Recently, direct methanol fuel cells (DMFCs) have been regarded as the greatest energy-producing owing to their low operating temperature, high production rate of methanol, and low greenhouse gas emission. However, the energy conversion efficiency of the DMFCs is still unsatisfactory due to the slow kinetics of the fuel oxidation reaction. So, an economic electrocatalyst with high efficiency and good stability is still needed. Herein, low-cost nanocomposites of (Ni/Cu/N) MOF and palm pollen-derived G-graphite were prepared with different ratios namely, (1:1), (1:2), and (2:1) through a solvothermal reaction. The nanocomposites were characterized via X-ray diffraction (XRD), Scanning electron Microscopy (SEM), Fourier transform infrared (FTIR), Thermal gravimetric analysis (TGA), and, (Brunauer–Emmett–Teller) technique (BET). Electrodes have been tested as electro-catalysts for methanol-oxidation reaction (MOR) in a basic medium. As revealed from the cyclic voltammetry measurements, all electrodes exhibit a good response to MOR, being the nanocomposite with the ratio between (Ni/Cu/N) MOF and G-graphite (2:1) is the best with an oxidation peak current density of 55 mA/cm2 at a scan rate of 50 mV/s, with an onset potential of 0.35 V, and stability reaches 96 %. The electrochemical impedance spectroscopy (EIS) test showed that the ratio (2:1) has the lowest charge transfer resistance, RCT, of 5.21 Ω which confirms its higher electrochemical activity. This superior performance of the (Ni/Cu/N) MOF and G-graphite (2:1) over other reported MOF-based electrocatalysts is attributed to the synergistic effect of the (Ni/Cu/N) MOF electrocatalyst, wherein Ni and Cu provide redox electrocatalytic active sites for MOR while the G-graphite contributes towards the chemical stability and electrical conductivity of the electrode, respectively. The good activity and stability of the prepared electrodes suggest the potential use of these electrodes as electrocatalysts for MOR in direct methanol fuel cells (DMFCs).This study opens the venue for valorizing the natural wastes derived graphitic material as stable supporting material in Mof based composites electrodes for MOR.

A Comprehensive Review on Electrocatalytic Applications of 2D Metallenes.

This review introduces metallenes, a cutting-edge form of atomically thin two-dimensional (2D) metals, gaining attention in energy and catalysis. Their unique physicochemical and electronic properties make them promising for applications like catalysis. Metallenes stand out due to their abundance of under-coordinated metal atoms, enhancing the catalytic potential by improving atomic utilization and intrinsic activity. This review explores the utility of 2D metals as electrocatalysts in sustainable energy conversion, focusing on the Oxygen Evolution Reaction, Oxygen Reduction Reaction, Fuel Oxidation Reaction, and Carbon Dioxide Reduction Reaction. Aimed at researchers in nanomaterials and energy, the review is a comprehensive resource for unlocking the potential of 2D metals in creating a sustainable energy landscape.

Experimental study on microwave-induced puffing, micro-explosion, and combustion characteristics of ammonium dinitramide-based liquid propellant droplets

Microwave ignition technology has the advantages of high ignition energy, stable ignition, and spatial multi-point ignition. These advantages make this technology promising for future application in green single-component propellants. In this paper, the ignition characteristics of ammonium dinitramide (ADN)-based liquid propellant droplets under the influence of microwaves at room temperature are investigated using experimental methods. The effects of microwave power on puffing, micro-explosion, and combustion behavior of ADN-based liquid propellant droplets were studied. The droplet and flame diameters were statistically related to time, and the microwave-assisted droplet ignition mechanism was analyzed. A new rectangular waveguide resonant cavity was designed in which the droplet is placed at the maximum electric field strength of the device. The droplet morphology and flame profile inside the resonant cavity were photographed with a high-speed camera. The experimental results showed that the microwave positively influenced the puffing, micro-explosion, and combustion behavior of droplets. When the microwave power was increased from 200 to 280 W, the total droplet evaporation time and ignition delay time were reduced by 56.5% and 35.2%, respectively. The positive effects of microwaves on combustion have been summarized as the thermal effect of microwaves on polar molecules and the promotion of fuel oxidation reactions by microwave-induced plasma. The plasma was found to control the development of the initial flame propagation front and to influence the temperature during the combustion reaction process. In this paper, we propose the mode of droplet combustion under microwave induction as a plasma discharge and several stages of the droplet combustion process. This research provides novel insight into the study of the microwave ignition mechanism of liquid fuels.

Nanoarchitectonics of Metallene Materials for Electrocatalysis.

Controlling the synthesis of metal nanostructures is one approach for catalyst engineering and performance optimization in electrocatalysis. As an emerging class of unconventional electrocatalysts, two-dimensional (2D) metallene electrocatalysts with ultrathin sheet-like morphology have gained ever-growing attention and exhibited superior performance in electrocatalysis owing to their distinctive properties originating from structural anisotropy, rich surface chemistry, and efficient mass diffusion capability. Many significant advances in synthetic methods and electrocatalytic applications for 2D metallenes have been obtained in recent years. Therefore, an in-depth review summarizing the progress in developing 2D metallenes for electrochemical applications is highly needed. Unlike most reported reviews on the 2D metallenes, this review starts by introducing the preparation of 2D metallenes based on the classification of the metals (e.g., noble metals, and non-noble metals) instead of synthetic methods. Some typical strategies for preparing each kind of metal are enumerated in detail. Then, the utilization of 2D metallenes in electrocatalytic applications, especially in the electrocatalytic conversion reactions, including the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, fuel oxidation reaction, CO2 reduction reaction, and N2 reduction reaction, are comprehensively discussed. Finally, current challenges and opportunities for future research on metallenes in electrochemical energy conversion are proposed.

Electronic Activation during Nanoparticle Exsolution for Enhanced Activity at Elevated Temperature.

Nanoparticle (NP) exsolution from perovskite-based oxides matrix upon reduction has emerged as an ideal platform for designing highly active catalysts for energy and environmental applications. However, the mechanism of how the material characteristics impacts the activity is still ambiguous. In this work, taking Pr0.4Sr0.6Co0.2Fe0.7Nb0.1O3 thin film as the model system, we demonstrate the critical impact of the exsolution process on the local surface electronic structure. Combining advanced microscopic and spectroscopic techniques, particularly scanning tunneling microscopy/spectroscopy and synchrotron-based near ambient X-ray photoelectron spectroscopy, we find that the band gaps of both the oxide matrix and exsolved NP decrease during exsolution. Such changes are attributed to the defect state within the forbidden band introduced by oxygen vacancies and the charge transfer across the NP/matrix interface. Both the electronic activations of oxide matrix and the exsolved NP phase lead to good electrocatalytic activity toward the fuel oxidation reaction at elevated temperature.

A systematic analysis of chemical mechanisms for ethylene oxidation and PAH formation

Accurate prediction of soot formation and evolution remains a formidable challenge due to the complex interaction between gas-phase composition and solid-phase particles. Recent studies have shown that the choice of gas-phase mechanisms is of primary importance in affecting predictability. In this work, a systematic analysis of ethylene (C2H4) combustion mechanisms denoted as KAUST, Stanford, Aachen, Polimi, ABF, DLR/UT, Naples, Caltech, and SJTU, which have been widely used in the soot community, is performed to investigate their differences in fundamental chemistry, polycyclic aromatic hydrocarbon (PAH) chemistry, and soot prediction. It is found that the nine mechanisms exhibit large differences even in predicting canonical combustion properties (e.g., ignition delay time, laminar flame speed, and extinction strain rate), indicating significant variations in the fundamental chemistry. This is due to the fact that although most mechanisms share very similar dominant fuel-oxidation reactions, there are notable differences in the rate coefficients of sensitive reactions used in these mechanisms. Owing to the uncertainties in the fundamental chemistry, the predictions of C2H2 from the nine mechanisms show significant differences, which contributes to the differences in soot precursor prediction, in conjunction with the difference in benzene (A1) formation pathways demonstrated by the element flux analysis of the C atom. Furthermore, it is found that PAHs containing two rings play a dominant role in soot formation for most mechanisms. Moreover, it is observed that while Caltech and SJTU significantly under estimate soot formation, they reasonably reproduce its sensitivity to strain rate. These results indicate that despite substantial advances in the development of C2H4 oxidation and PAH formation chemistry, the various existing mechanisms lead to significant differences in predicting soot concentrations which can be traced back to considerable differences in both fundamental chemistry and PAH chemistry. This suggests that the fundamental chemistry should be calibrated or improved before further development of PAH chemistry and soot models.

Діоксид цирконію, стабілізований оксидами ітрію та церію (8Ce2YSZ), для анодів керамічних паливних комірок та електролізерів

Solid oxide fuel cells (SOFC) are among the most promising technologies for the electricity generation due to their high efficiency, reliability, flexibility in fuel selection, absence of valuable platinum group metal catalysts, safety and environmental friendliness.Typically, the SOFC is built on the basis of its anode, which is actually also its carrier. This is due to the researchers wish to minimize the ohmic resistance of the electrolyte layer via its thinning that is extremely critical for reducing SOFC operating temperature. In this regard, the anode must be strong enough both to make it easier to handle when making the whole cell and to ensure its stable operation. In addition to the carrier function, the anode shall provide sites for reacting gaseous fuel with oxygen ions, which are delivered through the electrolyte, and supplying the fuel gas components to the reaction sites and removing the fuel oxidation reaction products to the outside.The work deals with the comparative study of ceramic materials based on ZrO2, co-stabilized with CeO2 and Y2O3, and stabilized with Y2O3to be used in producing the SOFC anode, and for further structural optimization for future SOFCs.8Ce2YSZ ceramic samples made by hydrothermal synthesis (with two different modes of drying precipitation) have tetragonal phase and 6—8% residual porosity. The 8Ce2YSZ samples, showed the biaxial bending strength — 542 MPa and 486 MPa, respectively. The 8YSZ and 3YSZ samples have cubic phase with a strength of 181 MPa and tetragonal phase with a strength of 577 MPa, respectively at 1% porosity.The specific electrical conductivity of 8Ce2YSZ and 8YSZ is 1,1•10-3, 4•10-3 S/cm, 1,2•10-2 S/cm and 5,2•10-3, 2,7•10-2 S/cm, 9,3•10-2 S/cm at 600, 700, 800 °C, respectively. Keywords: solid oxide fuel cell, electrolyte, anode, zirconium dioxide, mechanical strength, ionic conductivity.

In situ growth of copper-iron bimetallic nanoparticles in A-site deficient Sr2Fe1.5Mo0.5O6-δ as an active anode material for solid oxide fuel cells

The design of active anode materials with abundant active sites for fuel oxidation reaction is highly desirable. In-situ exsolution of nanoparticles from perovskite oxides is an effective approach to maintain its nanoscale dimensions and provide efficient active sites. Herein, a promising anode material decorated with copper-iron bimetallic nanoparticles is prepared by in-situ exsolution from A-site deficient Sr1.9Fe1.5Mo0.5−xCuxO6-δ double perovskite. With the doping of Cu, the agglomeration of iron nanoparticles is highly inhibited under reducing environment and copper-iron bimetallic nanoparticles can be uniformly formed. Through high temperature reduction, Sr1.9Fe1.5Mo0.5O6-δ substrate is transferred to heterostructure consisting of a Ruddlesden-Popper phase (Sr3FeMoO6.5) and a perovskite phase. The in-situ exsolved copper-iron bimetallic nanoparticles on the heterostructure can provide abundant active sites for fuel oxidation and lead to an improvement of polarization resistance from 0.41 Ω·cm2 to 0.22 Ω·cm2 at 800 °C under H2. In addition, the maximum power density is increased to 574 mW cm−2, which is about 37% higher than that of Sr1.9Fe1.5Mo0.5O6-δ. The present study provides a potential strategy for developing efficient anode materials for solid oxide fuel cells.

A numerical investigation on the laminar flame speed of methane/air and iso-octane/air mixtures with ozone addition

A numerical study has been carried out to evaluate the influence of ozone addition on the laminar flame speed for both methane/air and isooctane/air mixtures under thermodynamic conditions typical of internal combustion engines. Ozone is a highly oxidising chemical species and modifies the fuel oxidation reaction pathways, mainly in the initial stages of combustion. In the case of alkanes, such as methane and isooctane, ozone enhances the laminar flame speed. This study aims to analyse similarities and differences of the flame structure of methane and isooctane for different values of ozone concentration and equivalence ratio and for a wide range of pressure and temperature conditions. A 1-D numerical model, validated against several experimental data taken from the scientific literature, has been employed and simulations have been carried out by using a chemical kinetic reaction mechanism for methane and three different mechanisms for isooctane. The results show that the laminar flame speed increases with ozone concentration in the range 0–7000 ppm. At 1 bar, the percentage enhancement in terms of LFS with the addition of 7000 ppm of ozone, compared to the case without ozone, is about 4% for both fuels, under stoichiometric conditions, as long as temperature is lower than about 540 K. On the other hand, at higher temperatures ozone addition enables the formation of a cool flame for isooctane/air mixtures, and the reactions follow a different path compared to the case with methane. This leads to a greater influence of ozone on the isooctane laminar flame speed. Besides, for isooctane/air stoichiometric mixtures, at 560 K with 7000 ppm ozone, LFS shows a non-monotonic behaviour with pressure, being higher at 20 bar than at 15 bar, which is somehow unexpected. If the reactants temperature increases, the non-monotonic trend appears at lower pressures and lower ozone concentrations and is due to the fast ozone decomposition, promoted by the pressure increase. Such a decomposition enables fuel oxidation reactions by OH radicals in the cool flame region. This phenomenon does not occur for the methane case.

Robust in situ exsolved nanocatalysts on perovskite oxide as an efficient anode for hydrocarbon fueled solid oxide fuel cells

An in situ exsolved (Pr,Ba)Ox nanoparticle structure layered perovskite oxide anode can effectively promote the fuel oxidation reaction, enabling the significantly enhanced electrochemical performance and considerable stability.

Ultrathin PtRu Nanowires as Efficient and Stable Electrocatalyst for Liquid Fuel Oxidation Reactions

Direct liquid fuel cells (DLFCs) are promising clean energy conversion devices for their high energy density, low environmental pollution, and convenient transportation and storage. However, the commercialization of DLFCs is still limited by the lack of highly active and stable catalysts for the anodic oxidation of liquid fuels. Herein, a new class of ultrathin PtRu nanowires (NWs) with a diameter of 1.1 nm was synthesized via a colloidal chemistry strategy. The as-made ultrathin PtRu NWs can not only expose large active sites but also enhance the kinetics of methanol oxidation reaction, which was confirmed by the in situ Fourier transform infrared (FTIR) spectroscopy. Consequently, ultrathin PtRu NWs exhibit greatly boosted activity and stability for methanol and ethanol oxidation reactions in an alkaline medium.

Investigation of Ni2+-doped ceria nanorods as the anode catalysts for reduced-temperature solid oxide fuel cells

Tailoring the surface chemistry of oxides has been widely used to adjust their catalytic behavior in the energy conversion and storage devices. Herein, nanorods of Ni2+-doped ceria (Ce1-xNixO2-δ, x = 0, 0.05, 0.1, 0.15) are synthesized via a modified hydrothermal method, and evaluated as the anode catalysts for reduced-temperature solid oxide fuel cells (SOFCs). X-Ray diffraction patterns of as-synthesized powders in air imply successful incorporation of Ni2+ into the fluorite lattice of ceria for x = 0.05 and 0.1, with a secondary phase of NiO observed for x = 0.15. Transmission electron microscopy (TEM) examination confirms a rod-like morphology with a diameter of 10–13 nm and a length of 55–105 nm. Exposure of these powders in H2 at 600°C results in exsolution of some spherical Ni particles of 11 nm in diameter. Electrochemical measurements on both symmetrical anode fuel cells and functioning cathode-supported fuel cells show an order of the catalytic activity toward hydrogen oxidation - CeO2-δ < Ce0·95Ni0·05O2-δ < Ce0·9Ni0·1O2-δ. The anode polarization resistances in 97% H2 – 3% H2O are 0.24, 0.31 and 0.37 Ω⋅cm2 for Ce0·9Ni0·1O2-δ, Ce0·95Ni0·05O2-δ and CeO2-δ at 600°C, respectively. Thin (La0·9Sr0.1) (Ga0.8Mg0.2)O3-δ-electrolyte fuel cells with nanostructured SmBa0.5Sr0·5Co2O5+δ cathodes and Ce0·9Ni0·1O2-δ anodes yield the highest power densities among the investigated series of anodes, e.g., 820 mW⋅cm−2 in 97% H2 – 3% H2O and 598 mW⋅cm−2 in 68% CH3OH - 32% N2. XPS analyses of reduced nanorods indicate that the highest catalytic activities of Ce0·9Ni0·1O2-δ toward fuel oxidation reactions should be correlated to the presence of highly active Ni nanoparticles and increased surface active oxygen, as confirmed by substantially facilitated extraction of the lattice oxygen on the surface by H2 in temperature-programmed reduction (TPR) measurements.

Understanding the oxygen-vacancy-related catalytic cycle for H2 oxidation on ceria-based SOFC anode and the promotion effect of lanthanide doping from theoretical perspectives

Lanthanide-doped ceria is known to be a promising solid-oxide-fuel-cell (SOFC) anode material. Understanding the catalytic cycle of fuel oxidation reaction on lanthanide-doped ceria is of great significance for the design of CeO2-based anode materials and catalytic processes with improved activity. Herein, we performed density functional theory (DFT) calculations on pure and Pr-, Nd-, Sm-, Gd-doped CeO2(111) to investigate the catalytic cycle of oxygen vacancy (Ov) generation and recovery in H2 oxidation process. Lanthanide doping promotes H2 dissociation, H2O formation, H2O desorption, and bulk O2− diffusion steps in the catalytic cycle. On the basis of thermodynamic and kinetic analysis, we propose that under anodic SOFC conditions, there is not a single stable Ov on pure, Pr-, Nd-, and Sm-doped surfaces because the first nearest-neighbor Ov is filled immediately upon formation, followed by the next catalytic cycle, while one Ov exists stably on Gd-doped surface, and subsequent catalytic cycle proceeds on the second nearest-neighbor vacancy site. The presence of a single Ov reduces the catalytic activity for H2 oxidation reactions on Gd-doped surface. Sm-doped ceria showed the best promotion effect for the whole Ov-related catalytic cycle, in agreement with the experimental observations.

Application of High-Temperature Raman Spectroscopy (RS) for Studies of Electrochemical Processes in Solid Oxide Fuel Cells (SOFCs) and Functional Properties of their Components

SOFC efficiency is directly determined by the electrodes, optimization of which is related to the study of the mechanisms of electrochemical current-generating reactions taking place. Such studies are tricky due to the high operating temperature of SOFCs, high current loads, and corrosive gas media. A promising research method is Raman spectroscopy (RS) under operating conditions of SOFC. At ISSP RAS, a combined experimental technique and setup have been created that combines the capabilities of traditional electrochemical methods, as well as high-temperature Raman spectroscopy [1]. In order to study the processes in the electrochemically active zone, a special geometry of samples was developed on basis of optically transparent single crystal membranes of an anionic conductor with a counter-electrode of a toroidal shape. With the use of this combined technique and special geometry of samples in previous works, studies of the kinetics of reduction and morphological changes of nickel in composite SOFC anodes were carried out. It was shown that the first reduction cycle differs significantly from the subsequent ones both in the initial delay and in the total time of the process. SEM studies have shown that these changes are associated with a morphological rearrangement that occurs during the first reduction cycle: the grain size of NiO is significantly reduced compared to the initial one. For model SOFCs investigated in the OCV mode [2] after the initial microstructural rearrangement in the redox cycle, the behavior of standard cermet anodes in a H2–N2 flowing atmosphere can be described using Avrami model. The influence of the composition of fuel on Raman spectra obtained from the internal interface in the current load mode was also investigated [3], and the correlations of obtained data with the cell voltage were studied. It was shown that the corresponding mechanisms that determine the reaction kinetics can be associated with the transfer of ions through the GDC|YSZ. Subsequent rate limiting steps such as electrochemical oxidation of hydrogen in the Ni-GDC layer are undetectable for the geometry under test due to the limited penetration depth of the laser beam. Comparative studies of model SOFCs with a supporting anode substrate (ASC) and a supporting solid electrolyte (ESC) were carried out using the in-situ RS technique [4]. It was shown that the addition of the GDC indicator layer makes it possible to carry out an in-situ study of the chemical potential of oxygen at the internal interface of the anode|electrolyte depending on current load or fuel mixture, but the GDC/YSZ two-layer thin-film electrolyte exhibits electronic or gas leakage due to poor stability in a reducing atmosphere. Despite the significantly lower internal resistance compared to the ESC, the quality of the ASC thin film membrane severely limits research depending on the operating temperature, current load and fuel composition. In this case, the use of thin-film membranes significantly reduces the effect of 8YSZ on the Raman spectra of the internal interface. After post-processing and normalization, the obtained Raman spectra show a similar effect of the current load or the hydrogen content in the fuel gas mixture on the GDC peak area (460 cm-1). The linear dependence of the OCV on the peak area of ~460 cm-1 makes it possible to assess the relationship between changes in the peak area and the evolution of the chemical potential of oxygen at the anode under a current load. Comparative analysis of the anodic impedance for different fuel mixtures suggests that spectroscopic measurements of the internal interfaces provide direct information on the contribution of the fuel oxidation reaction to the total losses in SOFC. In addition to studies of complete fuel cells, high-temperature Raman spectroscopy is used to study the structure of single-crystal samples of anionic conductors [5], including at the operating temperature of SOFCs. High-temperature RS allows one to obtain additional information on the microstructure of samples both at room temperature and at working temperature, where most other research methods do not allow research. New combined technique was used to study other components of high-temperature electrochemical devices: sealing glasses [6] for SOFCs and optical glasses [7]. This work was supported by Russian Scientific Foundation, grant no. 17-79-30071.[1] D.A.Agarkov et al. ECS Trans., vol.68, iss.1, pp.2093-2103 (2015).[2] D.A.Agarkov et al. Solid State Ionics, vol.302, pp.133-137 (2017).[3] D.A.Agarkov et al. Solid State Ionics, vol.319C, pp.125-129 (2018).[4] D.A.Agarkov et al. Solid State Ionics, vol.344, p.115091 (2020).[5] D.A.Agarkov et al. Solid State Ionics, vol.346, p.115218 (2020).[6] A.Allu et al. ACS Omega, vol.2, pp.6233-6243 (2017).[7] M.K.Kokila et al. Solid State Sciences, vol.107, p.106360 (2020). Figure 1

A microchannel reactor-integrated ceramic fuel cell with dual-coupling effect for efficient power and syngas co-generation from methane

Co-generation of electricity and syngas from methane via solid oxide fuel cells (SOFCs) to achieve zero emission is highly attractive for enhancing the energy efficiency of methane utilization. However, it remains a great challenge to simultaneously achieve high power output and syngas formation rate, and sufficient operational stability in existing SOFCs. In this work, we successfully demonstrate the efficient co-generation by the innovative integration of a catalytic microchannel reactor within anodes. The integrated anode has unique dendritic channels loaded with highly efficient nanofibrous Ni-based composite that functions as an internal catalyst bed reformer. The resulting SOFC demonstrates both thermal coupling and materials coupling effects between exothermal fuel oxidation reactions and endothermal reforming reactions and thus improves peak power density by 25 %, syngas yield by more than 2 times and improved operational stability compared to the SOFC without the microchannel reactor. The new SOFC design holds great potential for practical applications.

Recent Progress of Ultrathin 2D Pd-Based Nanomaterials for Fuel Cell Electrocatalysis.

Pd- and Pd-based catalysts have emerged as potential alternatives to Pt- and Pt-based catalysts for numerous electrocatalytic reactions, particularly fuel cell-related reactions, including the anodic fuel oxidation reaction (FOR) and cathodic oxygen reduction reaction (ORR). The creation of Pd- and Pd-based architectures with large surface areas, numerous low-coordinated atoms, and high density of defects and edges is the most promising strategy for improving the electrocatalytic performance of fuel cells. Recently, 2D Pd-based nanomaterials with single or few atom thickness have attracted increasing interest as potential candidates for both the ORR and FOR, owing to their remarkable advantages, including high intrinsic activity, high electron mobility, and straightforward surface functionalization. In this review, the recent advances in 2D Pd-based nanomaterials for the FOR and ORR are summarized. A fundamental understanding of the FOR and ORR is elaborated. Subsequently, the advantages and latest advances in 2D Pd-based nanomaterials for the FOR and ORR are scientifically and systematically summarized. A systematic discussion of the synthesis methods is also included which should guide researchers toward more efficient 2D Pd-based electrocatalysts. Lastly, the future outlook and trends in the development of 2D Pd-based nanomaterials toward fuel cell development are also presented.

Control-oriented modeling of diesel oxidation catalyst

Diesel oxidation catalyst outlet temperature control is crucial for heat management to realize diesel particulate filter active regenerative control. In order to control the temperature of the active regeneration process in the filter, the temperature response process of the semi-physical oxidation catalyst model structure is proposed as a multi-stage inertia plus delay, and the equivalent inlet temperature step of the fuel oxidation reaction of the exhaust pipe. Combined with the test test, the control oriented oxidation catalyst model is established.A control-oriented oxidation catalyst model was constructed. By analysed the oxidation catalyst working process, the main chemical reactions, heat and mass transfer processes occurring inside the carrier were analyzed. Three-dimensional CFD model and one-dimensional chemical reaction kinetics model were established respectively. The radial and axial temperature distribution of the carrier was analyzed by model simulation. Based on the analysis of the system characteristics, the multi-step inertia plus delay semi-physical model structure was proposed. Combined with the test, the control oriented oxidation catalyst model is established. Select the appropriate working conditions to identify and verify the model parameters. The results show that the third order model can well indicate the temperature response characteristics of the oxidation catalyst outlet temperature. Considering the complexity of the system, the first-order and third-order model are selected as the basis of the control system design.

Application of ion beam technology in (photo)electrocatalytic materials for renewable energy

The development of environmentally friendly, efficient, and universal access renewable energy technology is the key to achieve the goal of sustainable development. (Photo)electrochemical energy storage and conversion technology is an important part. Therefore, to realize the practical application of (photo)electrochemical energy technology, nanostructured catalytic materials need to be reasonably designed, synthesized, and modified. Ion beam technology is a powerful and versatile physical modification method. Modification of various catalytic materials from the surface to interface and thin films can be realized by controlling the species, energy, and fluence of implanted ions. Ion beam technology has its unique advantages, including its compulsivity of element doping and its high controllability, accuracy, and repeatability. It can realize arbitrary element doping and defect control of almost any material and finely control its concentration. This makes it possible for the ion beam technology to adapt to the modification requirements of catalytic materials to tailor the electronic structure, interface structure, and morphology of the materials more finely. Besides, a variety of strategies for material design can be realized using ion beams, including element doping, defect control, heterostructure construction, and micro/nanostructure formation, which may bring novel changes in catalytic materials. In this Review, we briefly introduce the principle of ion beam technology and introduce various ion beam technologies that can be applied to different catalytic material modification applications. We systematically review the research progress on the application of ion beam technology in photocatalytic, photoelectrocatalytic, and electrocatalytic materials for water splitting including bandgap engineering, defect engineering, heterostructure formation through ion doping, ion irradiation, ion sputtering, and their combined effects. The applications of ion beam technology on modification of fuel oxidation reaction and oxygen reduction reaction electrocatalysts for fuel cells are also introduced. The advantages of ion beam technology in the modification of catalytic materials are summarized. Several promising topics are proposed to look forward to the future development of ion beam technology in the field of catalytic materials.

Air‐Assisted Transient Synthesis of Metastable Nickel Oxide Boosting Alkaline Fuel Oxidation Reaction

AbstractConstruction of active and durable non‐noble‐metals based electrocatalysts is one of important requirements for the practical application and development of fuel cells, which are presently inhibited by relative sluggish charge transport and reaction kinetics. Herein, highly dispersed ultrathin carbon‐coated nickel oxide nanoparticles settled on carbon cloth (NiO@C/CC) as efficient catalysts for alkaline fuels oxidation are synthesized via an air‐assisted transient thermal shock strategy. This NiO@C/CC catalyst induces an outstanding catalytic activity (up to 119.1 mA cm−2) and durability (a little current decay during tests) in electrooxidation for ethanol, even for methanol and ethylene glycol, which outperforms most of the reported non‐noble metal catalysts. The excellent catalytic performance of NiO@C/CC is essentially attributed to the oxygen vacancies, high concentration, high‐valence‐state Ni, and carbon layers of NiO@C NPs, which contribute to regulate the surface properties and electronic structure, enhance charge transfer, and provide abundant active sites, promoting adsorption capacity of reactant molecules on its surface. The facile and promising air‐assisted transient thermal shock strategy can be extended to guide rational design and rapid synthesis of transition metal compounds as advanced catalysts for alkaline direct alcohol fuel cells.