Oxygen Storage Research Articles

Study on energy storage configurations and energy management strategy of an underwater hydrogen hybrid system

Enhancing the durability of unmanned underwater vehicles (UUVs) would facilitate maritime research, and hydrogen fuel cells are considered a feasible solution. In this paper, based on an underwater hydrogen hybrid system mainly driven by a hydrogen-air fuel cell stack and a battery, the energy management strategy and energy storage are investigated to enhance the endurance of UUV. The results exhibit that the proposed energy management strategy integrating equivalent hydrogen consumption minimization strategy with rule-based strategy (ECMS-RB strategy), effectively reduces fuel cell power fluctuations. It is noted that, this strategy increases the state of charge (SOC) of the battery by approximately 0.2 and prevents battery over-discharge, compared to the conventional state machine strategy under identical boundary conditions. Additionally, this paper compares the performance of energy storage systems and their coupling design with UUV. The results suggest that liquid hydrogen-liquid oxygen and metal hydride energy storage systems are preferable for UVVs to achieve neutral buoyancy. Under low-speed navigation conditions, increasing the UUV length from 1.5 m to 5.5 m enhances its endurance capability by a factor of 1.78, and raising the outer diameter from 0.1 m to 0.4 m increases the endurance capability by a factor of 5.44.

Cost-Benefit Analysis of Apple Scab Sanitation Practices for ULO-Stored Apple Fruit in Integrated and Organic Production Systems

ABSTRACT The economic viability of orchard sanitation practices, is crucial for sustainable apple production. However, our knowledge in this area is limited, particularly after the fruit is stored in the high-energy-consuming ultra-low oxygen (ULO) storage system. The objective of this 3-year study was to investigate the cost-benefit ratios of five sanitation treatments (lime sulfur-Lime-S, leaf collection-Collect-L, mulching-Mulch-C, lime sulfur + leaf collection, leaf collection + mulching) in integrated and organic apple orchards, considering the sale of apples after 6-month ULO storage. Cost-benefit analyses determined cost, total revenue, revenue for class 1 fruit (fruits without scab infection) and income surplus. Costs of ULO storage were twice higher in the integrated orchard (mean 3,064 EUR ha−1) than in the organic one (mean 1,512 EUR ha−1). Direct costs of the two combined sanitation treatments were significantly higher than the Lime-S and Collect-L treatments across all years and orchard systems. Analysis of variance for total revenue, revenue for class 1 fruit and income surplus revealed significant differences among years, sanitation treatments, and orchard systems. The total revenue and revenue for class 1 fruit were significantly higher in the integrated orchard (10,787 and 10,557 EUR ha−1, respectively) than in the organic one (8,713 and 7,742 EUR ha−1, respectively). The lowest total revenue and revenue for class 1 fruit were obtained in the non-sanitized control, while highest were recorded in the Collect-L or Collect-L + Mulch-C treatments. Collect-L and Collect-L + Mulch-C treatments provided the highest income surplus in all years and orchard systems. Kernel density estimations and frequency distributions indicated the widest variability for total revenue and revenue for class 1 fruit in the integrated orchard system. Correlation and linear regression analyses revealed significant relationship between total revenue and revenue for class 1 fruit in both orchard systems. In conclusion, our study demonstrates that Collect-L and Collect-L + Mulch-C treatments offer the greatest economic benefit after 6-month ULO storage regardless of the orchard system employed.

High response H2S chemiresistive gas sensor based on multidimensional CuO/CeO2: The application for real-time portable alarm device

Real-time monitoring of toxic and harmful hydrogen sulfide (H2S) is crucial in the extraction process of fossil fuels. However, in the process of detecting H2S, there will be difficulties in desorption, low response, poor anti-interference ability, and poor long-term stability. The multidimensional copper oxide (CuO) composite cerium oxide (CeO2) was synthesized by hydrothermal method and calcination techniques, and a gas sensor with easy desorption, high response, strong anti-interference ability, and excellent long-term stability for monitoring H2S was effectively prepared. Through various characterization tests such as X-ray diffraction (XRD) and scanning electron microscope (SEM), it was found that the composite material has multidimensional characteristics. When detecting 100 parts per million (ppm) of H2S at the optimal operating temperature of 180℃, the CuO/CeO2 gas sensor with the optimal ratio (nCu: nCe=1:1) showed an extremely high response (2010). At the same time, the gas sensor has extremely strong anti-interference ability and excellent long-term stability. In addition, these excellent H2S sensing properties are attributed to the excellent oxygen storage characteristics of CeO2 and the synergistic effect of CuO and CeO2. This provides more active sites for the absorption of H2S. Finally, to achieve real-time monitoring and alarm of H2S, a portable real-time monitoring and alarm device was made. When detecting different concentrations of H2S, it will flash corresponding color lights and give an alarm to achieve the monitoring function and ensure the safety and health of workers. The multi-dimensional CuO/CeO2 prepared has excellent gas sensing performance, providing a new method for H2S detection.

Boosting the active sites of Cu/Ce0.8Zr0.2O2 catalysts through tailored precipitation method

A reverse co-precipitation method was employed to increase the surface area of Ce0.8Zr0.2O2, resulting in boosting the active sites of Cu catalysts in the water–gas shift reaction (WGS). Active Cu sites and oxygen vacancy have been systematically controlled through the modification of physical properties and geometric configuration via a reverse co-precipitation of Ce0.8Zr0.2O2 support. The catalytic activity in WGS is primarily dependent on the number of active Cu species and is partially on the oxygen storage capacity. The kinetic results with Cu loadings revealed that the efficiency of active metal utilization was effectively enhanced by a reverse co-precipitation method, compared to the normal precipitation method, owing to the moderate metal–support interactions. The turnover frequency values were independent of Cu dispersion, highlighting the structure-insensitivity of Cu/Ce0.8Zr0.2O2 catalysts. This work suggests the possibility of controlling metal–support interactions through support synthesis methods.

Deciphering the Ce3+to Ce4+Evolution: Insight from X-ray Raman Scattering Spectroscopy at Ce N4,5Edges.

Cerium oxide, or ceria, (CeO2) is one of the most studied materials for its wide range of applications in heterogeneous catalysis and energy conversion technologies. The key feature of ceria is the remarkable oxygen storage capacity linked to the switch between Ce4+ and Ce3+ states, in turn creating oxygen vacancies. Changes in the electronic structure occur with oxygen removal from the lattice. Accordingly, the two valence electrons can be accommodated by the reduction of support cations where the electrons can be localized in empty f states of Ce4+ ions nearby.Quantifying the different oxidation states in situ is crucial to understand and model the reaction mechanism. Beside the different techniques to quantify Ce3+ and Ce4+ states, we discuss the use of X-ray Raman Scattering (XRS) spectroscopy as an alternative method. In particular, we show that XRS can observe the oxidation state changes of cerium directly in the bulk of the materials under realistic environmental conditions. The Hilbert++ code is used to simulate the XRS spectra and quantify accurately the Ce3+ and Ce4+ content. These results are compared to those obtained from in situ X-ray Diffraction (XRD) collected in parallel and the differences arising from the two different probes are discussed.

Impacts of MTBE in gasoline on the tailpipe ammonia emissions from China-6 certified passenger vehicles

Postcatalyst ammonia emissions from gasoline vehicles recently received attentions because of their contribution to the formation of urban secondary aerosols. To better understand whether fuel formulation would curb ammonia, the influence of methyl tertiary-butyl ether (MTBE) additive in gasoline on the tailpipe ammonia emissions from six China-6 compliant vehicles was investigated over the World Harmonized Light-duty Test Cycle (WLTC) at −7 °C and 23 °C. Ammonia emissions were measured with MTBE-free and 10 % MTBE-containing China-6 compliant gasoline fuels on the test vehicles. At – 7 °C, the ammonia emissions with and without MTBE addition ranged from 0.15 – 17.07 mg/km and 0.81 − 25.13 mg/km, respectively. At 23 °C, ammonia emissions were 0 − 7.4 mg/km for MTBE-containing fuel and 0 − 8.76 mg/km for MTBE-free fuel. More ammonia emissions were often observed as a result of maneuvering of enriched air-fuel mixtures to improve the combustion stability after cold-start and for de-NOx purpose. Due to the oxygen-containing nature of MTBE, its addition favors ammonia reduction in cold-start tests at – 7 and 23 °C. It is noted that “λ sweep”, an engine control strategy injecting extra fuel to deplete stored oxygen in the catalyst and suppress transient NOx formation during reacceleration after prolonged deceleration, may contribute to ammonia emissions due to the use of enriched air-fuel mixtures.

Boosting oxygen storage capacity of Fe-Cu bimetallic catalysts through sulfide modification for efficient and selective molecular oxygen activation

Molecular oxygen (O2), a reactive oxygen species precursor, has great potential for water purification, but its spin-forbidden resistance hinders its direct involvement in the redox reactions of organic compounds under mild ambient conditions. In this study, a facile strategy was employed to synthesize sulfide-modified Fe-Cu bimetallic catalysts (FeCu-S) to enhance the activation efficiency of O2. The results showed that the FeCu-S material exhibited a tenfold increase in O2 activation compared to that of the control group, primarily attributed to the increased specific surface area of the catalysts with an optimized Fe/Cu site distribution and promoted generation of Cu-containing crystalline phases (e. g., CuFeS2 and CuO) to significantly enhanced the oxygen storage capacity. Moreover, such Cu-containing crystalline phases strengthened surface electron transfer, thus remarkably promoting the selective generation of singlet oxygen (1O2) for sulfamethoxazole (SMX) degradation. The FeCu-S/O2 system maintained high activity after the fifth recycle with stable reaction pH and negligible leaching of Cu and Fe ions, also exhibited great performance in the advanced treatment of the real biological effluent and ultrafiltration effluent from landfill leachate, confirming its great potential for practical water purification applications.

Physiological Challenges and Adaptations in Competitive Freediving

Competitive freediving is associated with extreme physiologic challenges due to the effects of apnea, submersion in water, and increased ambient pressure. There has nevertheless been a continued progression of world records across freediving disciplines in recent years, with breath-hold times exceeding 10 minutes, and reaching diving depths beyond 200 meters of seawater. The main physiological determinants of breath-hold endurance are the available oxygen stores, i.e., intrapulmonary gas volume, inspired gas concentration, and rate of oxygen consumption. Other factors such as psychological and inherent factors contribute to the individual tolerance to an increasing respiratory stimulus with prolonged breath-hold duration. A freediving athlete must be able to tolerate apnea to stay underwater long enough to reach great distance or depth and resurface safely. Elite freedivers exhibit somewhat remarkable physiological adaptations such as a more pronounced diving-response and hypercapnia tolerance compared to non-divers, as well as metabolic and cerebrovascular adaptations. To reach great depths, elite freedivers employ a breathing technique called glossophyryngeal insufflation (GI) that is enlarging the ratio of total lung capacity to residual volume, thus, mitigating risk of lung squeeze and increasing intrapulmonary gas volume, and thereby enhancing available oxygen stores. Pulmonary anatomy and physiology could not be accounted to restrict the breath-hold diving depths achieved by competitive athletes. However, the acutely increased intrapulmonary pressure during GI is transmitted to the pulmonary vasculature, thereby eliciting a right ventricular pressure overload, and left ventricular dysfunction that may augment hypotension and syncope during glossopharyngeal insufflation. Due to extreme diffusion gradients between alveolar pN2 and N2 pressures in the body tissues at great depth, N2 will be forced into blood and body tissues during descent, elevating risk of N2 narcosis and decompression illness during deep dives. Breath-hold training and preparation have been shown to enhance breath-hold performance. This review highlights recent data on the profound cardiovascular, respiratory, and gas exchange effects that are observed in competitive freedivers, and discusses possible adaptations and risks for humans.

Oxygen and Electron Storage Effects in W-Modified Ceria Catalysts for Ammonia Conversion.

Tungsten-modified CeO2 is an excellent catalyst for the catalytic conversion of ammonia. However, the geometric and electronic properties of this catalyst and the detailed reaction mechanisms are not well understood. In this work, the potential configurations of various monomer tungsten oxides supported on the CeO2(111) surface (WOX(x=0-4)/CeO2(111)) are systematically studied and their relative stabilities are evaluated by using on-site Coulomb interaction corrected density functional theory calculations. Their performances are also investigated in enhancing the catalytic efficiency of NH3 adsorption and activation. It is found that the WOx clusters can always form tetrahedron-like structures on the CeO2(111) surface, and the CeO2(111) can exhibit both oxygen- and electron-storage roles to help the WOX maintain such tetrahedron-like WO4 structures and keep the W species at the highest 6+ state. Moreover, the flexibility of the tetrahedral WO4 structure leads to the preferential heterolytic NH3 dissociation at the WO sites, forming stable WNH2 and OH species. This study deepens the understanding of the unique oxygen- and electron-storage effects of the CeO2 support, it also provides valuable insights into the extraordinary catalytic properties of the W-modified CeO2 in NH3 conversion, paving the way for the rational design of more efficient CeO2-based NH3 treatment catalysts.

Diving into the influence of phosphorus on ceria-supported copper manganese bimetallic oxides for catalytic removal of carbon monoxide

The application of ceria-supported catalysts as promising catalysts for air pollutant abatement via heterogeneous catalytic processes is still a challenge. Phosphorus (P) is a potential threat to catalyst deactivation but has not been sufficiently explored. Herein, a systematic study reveals the poisoning behaviors of P on Cu-Mn bimetallic oxides supported by ceria (Cu-Mn/CeO2) as a typical case in CO oxidation and provides new insights into the deactivation mechanism. The P impregnation decreases the surface area of Cu-Mn/CeO2 and leads to the emergence of a new sheet morphology. The interactions between P and catalyst components (support and active species) result in the generation of dominant P species of PO43− and PO3−. The P addition also weakens the oxygen storage capacity of ceria and decreases the proportions of low-valent Cu and Mn, hindering electron transfers among metals. Furthermore, the reducibility and the adsorption and activation of O2 are limited in P-loaded Cu-Mn/CeO2 catalysts as found in H2-TPR and O2-TPD when increasing the P concentration. In situ DRIFTS experiments demonstrate that the inhibition of the formation and transformation of active intermediates, namely carbonyls and carbonates, is responsible for the poisoning behaviors of P in the pathway of CO oxidation over Cu-Mn/CeO2 catalyst.

Strain Effects on the Adsorption of Water on Cerium Dioxide Surfaces and Nanoparticles: A Modeling Outlook.

Nanocrystalline ceria exhibits significant redox activity and oxygen storage capacity. Any factor affecting its morphology can tune such activities. Strain is a promising method for controlling particle morphology, whether as core@shell structures, supported nanoparticles, or nanograins in nanocrystalline ceria. A key challenge is to define routes of controlling strain to enhance the expression of more active morphologies and to maintain their shape during the lifespan of the particle. Here, we demonstrate a computational route to gain insights into the strain effects on particle morphology. We use density functional theory to predict surface composition and particle morphology of strained ceria surfaces, as a function of environmental conditions of temperature and partial pressure of water. We find that adsorbed molecular water is not sufficient to shift stability and as such under all compressive and tensile strains studied, the most stable particle is of octahedral shape, similarly to the unstrained case. When dissociative water is involved at the surfaces of the particle, then the most stable particle morphology changes under high water coverage and tensile strain to cuboidal or truncated cuboidal shapes. This shift in shape is due to strain effects that affect the strength of water adsorption.

Deciphering the structural origin for the remarkable CO oxidation activities of the CuO-based catalysts with diverse morphological CeO2 supports

In this work, octahedral, cubic, particle-like, spherical and rod-shaped nano-CeO2 supports were synthesized by hydrothermal method. CuO/CeO2 catalysts were then prepared via an ultrasonic-assisted impregnation method, employing these differently shaped CeO2 supports. The resulting catalysts were tested for their performance in CO oxidation. The findings revealed that the CuO active sites significantly influenced the oxygen storage and release capacity of CeO2, thereby improving its catalytic activity for low-temperature CO oxidation. The key factors affecting the CO oxidation performance of CuO/CeO2 catalysts with different CeO2 morphologies were investigated through various characterizations. It was found that the specific surface area was not the primary factor in determining catalytic activity. Instead, the exposed crystal planes played a crucial role. By adjusting the crystal plane exposure of CeO2, the supported 1CuO/CeO2 catalysts exhibited different crystal surface configurations. Notably, the 1CuO/CeO2-S catalyst, with exposed (100) and (110) crystal planes, and the 1CuO/CeO2-P catalyst, with exposed (111), (100), and (110) planes, exhibited higher surface defect concentrations. This increased defect concentration facilitated the formation of Cu+ species, enhancing the redox properties and further improving the overall catalytic performance of CO oxidation.

Phase transition behaviors of Sr0.72Ca0.28Fe1-xNixO3-δ perovskite oxygen sorbents in a fixed bed reactor

Perovskite oxides have emerged as promising materials for oxygen storage applications, with their phase transitions being a key area of research. This study reports on the unique oxygen absorption and desorption breakthrough curves observed in the Sr0.72Ca0.28Fe1-xNixO3-δ series (x = 0.05) during fixed-bed experiments, featuring a distinct plateau. Through in situ X-ray diffraction (XRD) analysis, we demonstrated the reversible phase transition between the perovskite and brownmillerite (BM) structures. High Resolution Transmission electron microscopy (HR-TEM) further revealed the coexistence of these two phases within a granule. Focusing on the Sr0.72Ca0.28Fe0.95Ni0.05O3-δ sample at 550 °C, we conducted a detailed analysis of the oxygen absorption curve. Our findings indicate that the plateau arises from the oxygen-deficient BM phase absorbs oxygen to form the oxygen-saturated BM phase, followed by further oxygen absorption, leading to the formation of the perovskite phase. The inflection point in the oxygen absorption curve marks a critical oxygen concentration, signifying the threshold for effective oxygen absorption. This critical concentration is influenced by both material composition and operation temperature. Based on our observations, a phase diagram for x = 0.05 was drawn, encompassing both oxygen concentration and temperature. This diagram allows for the rational selection of operation temperatures and oxygen concentration swing ranges to enhance the performance of the oxygen sorbent. Our study highlights the crucial role of phase transition in oxygen storage, offering insights into the design and development of high-performance perovskite-based materials for various applications.

Best clinical practice experience at University of Gondar Comprehensive specialized Hospital Emergency and critical care Medicine department, A Case Study Under a resource limited set up

Abstract Background The emergency department (ED) is unique unstable environment where someone faces unscheduled and undifferentiated diseased patients, stressed families, unsettled staffs and unequitable resources.UoGCSH is the oldest in the Ethiopia and the only referral hospital for more than 13 million people from the five-zone north-west Ethiopia with 950 beds capacity. During the 2020 G.C a proposal paper was submitted to the administration bodies of the college and the hospital. The proposal was suggesting short term, mid-term and long-term quality improvement segments implemented in institutionally convenient manner. Objective To describe the transformation of emergency and critical care medical services at University of Gondar Comprehensive specialized hospital from scratch to the current status. Method A descriptive case study design was applied to narrate critical care service transformation at UoG Comprehensive Specialized Hospital. Since this case study is a data review from gathered secondary data, desk reviews of the emergency department, quality directorate data review, and the annual audit report review, there was no need for IRB approval. Result and recommendation After a year of renovation, we were able to organize a newly refurbished emergency room having a triage area with adequate reception space, Red resuscitation area with 10 beds (considering patient overflow), Orange with 18 beds, Yellow with 10 beds and floater area, isolation room, decontamination room, ED laboratory, main store, disaster store and piped oxygen system to all beds. we have gone a long journey in bringing those promised practices into demonstrable practice and finally replicable prototypic best practice. Even though we paced extra miles in achieving this status. Standard emergency room work flow implementation enable us to control the day-to-day patient and attendant crowding that impedes the anticipated medical treatment outcome and result in a significant dissatisfaction.Despite this achievement the trauma center establishment and high-quality patient care is recommended.

Effect of SiCN thin film interlayer for ZnO-based RRAM.

This study investigates the effect of silicon carbon nitride (SiCN) as an interlayer for ZnO-based resistive random access memory (RRAM). SiCN was deposited using plasma-enhanced chemical vapor deposition (PECVD) with controlled carbon content, achieved by varying the partial pressure of tetramethylsilane (4MS). Our results indicate that increasing the carbon concentration enhances the endurance of RRAM devices but reduces the on/off ratio. Devices with SiCN exhibited lower operating voltages and more uniform resistive switching behavior. Oxygen migration from ZnO to SiCN is examined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses, promoting the formation of conductive filaments (CFs) and lowering set voltages. Additionally, we examined the impact of top electrode oxidation on RRAM performance. The oxidation of the Ti top electrode was found to reduce endurance and increase low resistive state (LRS) resistance, potentially leading to device failure through the formation of an insulating layer between the electrode and resistive switching material. The oxygen storage capability of SiCN was further confirmed through high-temperature stress tests, demonstrating its potential as an oxygen reservoir. Devices with a 20 nm SiCN interlayer showed significantly improved endurance, with over 500 switching cycles, compared to 62 cycles in those with a 5 nm SiCN layer. However, the thicker SiCN layer resulted in a notably lower on/off ratio due to reduced capacitance. These findings suggest that SiCN interlayers can effectively enhance the performance and endurance of ZnO-based RRAM devices by acting as an oxygen reservoir and mitigating the top electrode oxidation effect.

The impact of support selection and Co loading amount on the catalytic performance for methane combustion

Methane (CH4) is a key component of natural gas and is essential for energy production and utilization. However, due to its strong greenhouse effect, efficient catalytic combustion methods are needed to convert it into CO2 and H2O. This study systematically evaluates the catalytic performance of Co, CoO, and Co3O4 in methane catalytic combustion, particularly highlighting the superior activity of Co3O4. To improve catalytic efficiency, this paper examines the effects of SiO2, Al2O3, and CeO2 as support materials using co-precipitation and impregnation methods. The results show a significant improvement in the catalytic activity of Co3O4 supported on CeO2, attributed to CeO2's unique redox properties and high oxygen storage capacity. Additionally, the study explores the impact of different loading amounts (5%, 10%, 15%, 20%) of Co3O4(x)-CeO2 catalysts on their performance. The optimal 10%wt Co3O4–CeO2 catalyst achieves methane conversion rates of 10%, 50%, and 90% at temperatures of 376 °C, 473 °C, and 578 °C, respectively, demonstrating exceptional stability during a 20-h stability test and the ability to adapt to fluctuations in CH4 concentrations in low-oxygen environments, while also exhibiting significant catalytic activity across a range of methane concentrations from 0.5% to 2.5%. These findings provide important theoretical and experimental guidance for the application of cobalt-based catalysts in CH4 combustion, paving the way for future catalyst design and optimization.

Myoglobin inhibits breast cancer cell fatty acid oxidation and migration via heme-dependent oxidant production and not fatty acid binding

The monomeric heme protein myoglobin (Mb) is aberrantly expressed in approximately 40 % of breast tumors. Mb expression is associated with better patient prognosis, yet the molecular mechanisms underlying this effect are unclear. In muscle, Mb's heme moiety confers oxygen storage and delivery. However, prior studies demonstrate that low levels of Mb in cancer cells preclude this function. Several studies propose a fatty acid binding function for Mb via lysine residue K46. Because cancer cells can upregulate fatty acid oxidation (FAO) to fuel cell migration, we tested whether Mb-mediated fatty acid binding modulates FAO and migration. We demonstrate that stable expression of human Mb in MDA-MB-231 breast cancer cells decreases cell migration and FAO. Site-directed mutagenesis of Mb K46 disrupted fatty acid binding but did not improve FAO or migration. Conversely, cells expressing Apo-Mb (with disrupted heme binding) did not show impaired FAO or migration rates, suggesting Mb attenuates FAO and migration via a heme-dependent mechanism rather than through fatty acid binding. Mb's heme-dependent oxidant generation dysregulates migratory gene expression, which is reversed by catalase treatment. Collectively, these data demonstrate that Mb's heme-dependent oxidant production decreases breast cancer cell migration, prompting therapeutic strategies to modulate oxidant production and Mb in tumors.

Nickel doped enhanced LaFeO3 catalytic cracking of tar for hydrogen production

The transformation of biomass into green energy was pivotal for sustainable development, yet the efficient conversion of biomass-derived tar into hydrogen-rich syngas remained a significant challenge. This study addressed the catalytic demand for hydrogen production from tar, focusing on the development of LaNixFe1-xO3 perovskites as catalysts. A series of LaNixFe1-xO3 perovskites with varying nickel doping levels (x=0, 0.25, 0.5, 0.75, 1) were synthesized to evaluate their catalytic performance in converting toluene, a representative tar component, into hydrogen. The LaNi0.5Fe0.5O3 catalyst demonstrated the highest hydrogen yield (14.5L/6h) and volume percentage (82.9V/V%), highlighting the optimal nickel doping level for enhancing hydrogen production. The hydrogen production performance of LaNixFe1-xO3 was significantly affected by nickel doping. In particular, a small amount of nickel doping can significantly enhance the hydrogen production capacity of LaFeO3 and maintain good reaction stability. The enhanced performance was attributed to the high oxygen storage capacity of perovskite, which facilitated the removal of surface carbon and promotes the methanation reaction. Notably, the total content of defect oxygen and surface adsorbed oxygen/hydroxyl groups significantly impacted the hydrogen production efficiency. These findings indicated that LaNi0.5Fe0.5O3 was an effective catalyst for converting biomass-derived tar into hydrogen-rich syngas, offering a promising solution to the catalytic demand in the hydrogen production system.

A detailed characterization study of Ni/CeO2 catalysts identifies Ni availability as the primary factor affecting CO2 methanation performance

The structure of a catalyst has a strong impact on its performance. Here we investigate the physicochemical properties of Ni/CeO2 in an attempt to draw structure–activity relationships for CO2 methanation. A combination of characterisation methods (X-ray diffraction (XRD), 4D Scanning Transmission Electron Microscopy (4D-STEM), CO chemisorption and oxygen storage capacity study etc.) clearly demonstrates the effect of Ni crystallite size, Ni availability (i.e. catalytically accessible Ni) and oxygen vacancies at the Ni-CeO2 interface in Ni/CeO2 during CO2 methanation. Among them, the role of exposed Ni active sites is highlighted, and two possible optimisation schemes i.e. changing the support calcination temperature and the final calcination atmosphere are proposed to obtain a better dispersal of Ni NPs (nanoparticles) on CeO2. Both modification methods do not affect the reaction route, and the activity differences of Ni/CeO2 can be explained by the various hydrogenation rate of formate species, as confirmed by in situ diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS) measurements.

Enhancing Ce-Co interfacial effects via special petal-pollen morphology construction to achieve efficient toluene removal

Interfacial effects provide an effective means to construct multi-metal interactions and design efficient catalysts for VOCs purification, while morphology construction remains a common tactic to optimize the efficiency of these catalysts. In the present work, the Co-Ce bimetal interface was effectively constructed by morphological regulation, and the coupling of the interfacial effect modulation and the special morphological structure was realized, resulting in superior catalyst performance. Among the series catalysts, CeCoOx-H demonstrated the optimized activity with 90 % toluene conversion at 250 °C while maintaining good results in a 50 h stability test. And the systematic characterization revealed that the structural changes and interfacial effects induced by morphological modulation would increase the structural defects, improving surface reactive oxygen and oxygen vacancy content, oxygen storage capacity, oxygen motivity and low-temperature reductivity, which account for promising catalytic performance of CeCoOx-H. Furthermore, in-situ DRIFTS revealed the following decomposition routes for toluene on the CeCoOx-H catalyst surface: toluene → benzyl alcohol → benzaldehyde → benzoate → phenol → maleate → acetate → formate → carbon dioxide. In particular, the decomposition of benzaldehyde and benzoate may be the key steps in toluene catalytic oxidation. Also, the characterization unveiled that the rich adsorption sites brought by the interfacial construction are not negligible in boosting the catalytic performance.