Modification of MgH2 hydrogen storage performance by nickel-based composite catalyst Ni/NiO.

In this study, the Ni/NiO catalyst was demonstrated to enhance the hydrogen storage performance of MgH2. The dehydrogenation of MgH2+10 wt% Ni/NiO started at approximately 180 °C, achieving 5.83 wt% of dehydrogenation within 10 min at 300 °C. Completely dehydrogenated, MgH2 began to rehydrogenate at about 50 °C, absorbing about 4.56 wt% of hydrogen in 10 min at 150 °C. In addition, the activation energies of dehydrogenation and rehydrogenation of MgH2+10 wt% Ni/NiO were 87.21 and 34.84 kJ/mol. During the dehydrogenation/rehydrogenation cycle, Mg2Ni/Mg2NiH4 could promote hydrogen diffusion, thus enhancing the hydrogen storage performance of Mg/MgH2.

Associations between waist circumference, central obesity, and the presence of non-valvular atrial fibrillation patients with heart failure.

Background: Reportedly, there is a clear correlation between waist circumference (WC) and atrial fibrillation (AF). However, there is no specific discussion about the relationship between WC and non-valvular AF (NVAF) patients with heart failure. Our main purpose was to study the relationship between WC, central obesity (CO), and NVAF patients with heart failure. Methods: This is a retrospective cohort study. A total of 3,435 patients with NVAF in the First Affiliated Hospital of Xinjiang Medical University from January 2015 to December 2017 were enrolled. The targeted independent variable and the dependent variable were WC and CO and the presence of NVAF with heart failure, respectively. Univariate, multiple regression, and subgroup analyses were used to analyze their relationship. We used the receiver operating characteristic (ROC) curve to choose the better predictor of NVAF with heart failure between WC and CO and calculated the proposed cut-off value of WC in males and female separately. Results: The identified risk factors of NVAF with heart failure were sex, height, WC, CO, body mass index (BMI), fasting blood glucose (FBG), homocysteine (HCY), triglyceride (TG), low-density lipoprotein cholesterol (LDLC), hypertension, diabetes mellitus (DM), stroke, vascular disease, and plaque. Then, a binary logistic regression model indicated that the occurrence of NVAF patients with heart failure increased 10% with WC increasing 1 cm and had a 2.8-fold increased risk with CO compared to those without. The predictive value [area under the ROC curve (AUC)], specificity, sensitivity, and accuracy of WC for the disease risk of NVAF with heart failure were higher than those of CO. The proposed cut-off value of WC was 91.85 cm for males and 93.15 cm for females. The diagnostic value of WC for NVAF with heart failure was higher for females than it was for males. Conclusions: Our research found that WC is related to the presence of heart failure in the patients with NYAF and can predict the presence of NVAF with heart failure. Our findings may help to improve the treatment and care strategies of NVAF individuals with abdominal obesity.

Chylopericardium following esophagectomy: a case report and systematic review.

BACKGROUND: Chylopericardium is a rare condition characterized by the accumulation of chyle in the pericardial space. It is most commonly caused by thoracic duct injury. Chylopericardium following esophagectomy is extremely rare but can cause life-threatening complications. This report presents a case of chylopericardium post-esophagectomy, resulting in cardiac tamponade and cardiac arrest. A systematic literature review was also conducted to facilitate the understanding of this rare condition. CASE PRESENTATION: A 41-year-old male was admitted to our hospital with intermediate to highly differentiated squamous cell carcinoma of the mid-thoracic esophagus (clinical T4NxM0). He underwent thoracoscopic-laparoscopic esophagectomy with cervical anastomosis. On postoperative day 1, patient had a cardiac arrest secondary to cardiac tamponade, requiring emergency ultrasound-guided drainage. The drained fluid was initially serous but became chylous after the administration of enteral nutritional emulsion. As a result of significant daily pericardial drainage, patient subsequently underwent thoracic duct ligation. The amount of drainage was substantially reduced post-thoracic duct ligation. Over a period of 2 years and 7 months, patient recovered well and tolerated full oral diet. A comprehensive literature review was conducted and 4 reported cases were identified. Among these cases, three patients developed pericardial tamponade secondary to chylopericardium post-esophagectomy. CONCLUSION: Chylopericardium is a rare but serious complication post-esophagectomy. Prompt echocardiography and thorough pericardial fluid analysis are crucial for diagnosis. Thoracic duct ligation has been shown to be an effective management approach for this condition.

Dapagliflozin Alleviates Myocardial Ischaemia Reperfusion Injury by Activating Mitophagy via the AMPK-PINK1/Parkin Signalling Pathway.

INTRODUCTION: Myocardial ischaemia reperfusion injury (MIRI) determines infarct size and long-term outcomes after acute myocardial infarction (AMI). Dapagliflozin, a sodium-glucose cotransporter 2 inhibitor, alleviates MIRI in animal models. METHOD: We investigated the potential mechanisms underlying the cardioprotective effect of dapagliflozin against MIRI, focusing on mitochondrial injury and mitophagy. MIRI mouse and H9C2 cell models were established. RESULTS: 2,3,5-Triphenyltetrazolium chloride (TTC) staining showed a significant alleviation of MIRI after pre-treatment of dapagliflozin compared to the model group (14.91±1.76 vs. 40.47±3.69%). Data from the pre-treatment dapagliflozin group showed a significant decrease in left ventricular ejection fraction (LVEF) (44.8±2.7 vs. 28.5±5.3%, P<0.01), left ventricular end-diastolic volume (LVEDV) (70.6±9.5 vs. 93.5±13.8 ul, P<0.05), and left ventricular end-systolic volume (LVESV) (39.0± 8.3 vs. 67.9±13.7 ul, P<0.05) compared to the model group. Dapagliflozin also reduced the levels of reactive oxygen species (ROS) and fragmented mitochondrial DNA, reversed the decrease in mitochondrial membrane potential, and suppressed apoptosis. Further study showed that dapagliflozin could protect against mitochondrial injury by rapidly clearing damaged mitochondria via mitophagy in a phosphatase and tensin homologue (PTEN)-induced putative kinase 1 (PINK1)/parkindependent manner. Dapagliflozin regulated mitophagy in cardiomyocytes by suppressing the adenosine 5'monophosphate-activated protein kinase (AMPK)-PINK1/parkin signalling pathway, resulting in attenuated MIRI. CONCLUSION: Dapagliflozin alleviated MIRI by activating mitophagy via the AMPK-PINK1/parkin signalling pathway.

Research on CCHP Design and Optimal Scheduling Based on Concentrating Solar Power, Compressed Air Energy Storage, and Absorption Refrigeration.

In response to the country's "carbon neutrality, peak carbon dioxide emissions" task, this paper constructs an integrated energy system based on clean energy. The system consists of three subsystems: concentrating solar power (CSP), compressed air energy storage (CAES), and absorption refrigeration (AR). Among them, thermal energy storage equipment in the photothermal power generation system can alleviate the fluctuation of solar energy and provide a stable power supply for the system. The compression heat generated during the compression process of the CAES system can be recovered through heat transfer oil to provide a heat load. The compressed air in the air accumulator (ACC) expands in the air turbine to provide an electric load. The low-temperature exhaust gas discharged from the turbine can provide cool load. First, a multienergy system that includes CSP, CAES, and AR is built. Then, the system takes the lowest economic cost as the objective function and constructs the system day-ahead scheduling model. Finally, for data obtained from scene reduction, the commercial optimization software Gurobi is invoked through YALMIP to solve the model. The results show that the three subsystems achieve multienergy complementarity; system operating costs are reduced by 59.94% and fully absorb wind and solar energies by the system.

Spontaneous oesophageal perforation secondary to renal colic.

Boerhaave syndrome is a rare but potentially life-threatening condition that involves a full-thickness tear of the oesophagus. It accounts for around 15% of all cases of oesophageal perforations and is associated with up to 40% of mortality. Vomiting has been found to be associated with the development of Boerhaave syndrome. However, the aetiology of vomiting varies broadly in the available literatures from alcohol indulgence to marathon running, and from panic attack to radiotherapy for cancer. We present here an unusual case of Boerhaave syndrome where the patient developed spontaneous oesophageal perforation in the setting of renal colic.

What do we know about platelets in myocardial ischemia-reperfusion injury and why is it important?

Myocardial ischemia-reperfusion injury (MIRI), the joint result of ischemic injury and reperfusion injury, is associated with poor outcomes in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention. Accumulating evidence demonstrates that activated platelets directly contribute to the pathogenesis of MIRI through participating in the formation of microthrombi, interaction with leukocytes, secretion of active substances, constriction of microvasculature, and activation of spinal afferent nerves. The molecular mechanisms underlying the above detrimental effects of activated platelets include the homotypic and heterotypic interactions through surface receptors, transduction of intracellular signals, and secretion of active substances. Revealing the roles of platelet activation in MIRI and the associated mechanisms would provide potential targets/strategies for the clinical evaluation and treatment of MIRI. Further studies are needed to characterize the temporal (ischemia phase vs. reperfusion phase) and spatial (systemic vs. local) distributions of platelet activation in MIRI by multi-omics strategies. To improve the likelihood of translating novel cardioprotective interventions into clinical practice, basic researches maximally replicating the complexity of clinical scenarios would be necessary.

Growth history of hepatitis C virus among HIV/HCV co-infected patients in Guizhou Province.

Background: The evolutionary and epidemiological history and the regional differences of various hepatitis C virus (HCV) genotypes are complex. Our aim was to better understand the molecular epidemiology and evolutionary dynamics of HCV among HIV/HCV co-infected individuals in Guizhou Province. This information could contribute to improve HCV prevention and control strategies in Guizhou and surrounding provinces. Methods: The HCV RNA was extracted from the serum of HIV/HCV co-infected patients, and reverse transcription/nested PCR was performed to amplify nucleotide sequences of the C-E1 region. Then, the successfully amplified sequences were selected for phylogenetic analysis. The available C-E1 region reference sequences from the surrounding provinces of Guizhou (Guangxi, Yunnan, Hunan, and Sichuan) were retrieved in GenBank, and the evolutionary analysis by Bayesian Markov chain Monte Carlo (MCMC) algorithm was performed using BEAST software to reconstruct a phylogeographic tree in order to explore their migration patterns. Finally, the epidemiological history of HCV in the Guizhou region was retraced by reconstructing Bayesian skyline plots (BSPs) after excluding sequences from surrounding provinces. Results: Among 186 HIV/HCV co-infected patients, the C-E1 region sequence was successfully amplified in 177 cases. Phylogenetic analysis classified these sequences into six subtypes: 1a, 1b, 3a, 3b, 6a, and 6n. Among them, subtype 6a was the most dominant strain (n = 70), followed by 3b (n = 55), 1b (n = 31), 3a (n = 11), 1a (n = 8), and 6n (n = 2). By reconstructing the phylogeographic tree, we estimated that the 6a strain in Guizhou mainly originated from Yunnan and Guangxi, while the 3b strain emerged due to transmission from the IDU network in Yunnan. Subtypes 1b, 3a, 3b, and 6a, as the major subtypes of HCV in HIV/HCV co-infected individuals in Guizhou, emerged and later grew more rapidly than the national average. Notably, BSPs of the currently prevalent HCV predominant strain subtype 6a in Guizhou have shown a rapid population growth since 2004. Although the growth rate slowed down around 2010, this growth has continued to date. Conclusion: Overall, despite the improvement and implementation of a series of HCV prevention and control policies and measures, a delayed growth pattern may indicate a unique history of the spread of 6a in Guizhou. Its trend as the dominant strain in Guizhou in recent years may continue to increase slowly over subsequent years.

Characteristics, prognostic determinants of monocytes, macrophages and T cells in acute coronary syndrome: protocol for a multicenter, prospective cohort study.

BACKGROUND: Acute coronary syndrome(ACS) is the leading cause of mortality and disability worldwide. Immune response has been confirmed to play a vital role in the occurrence and development of ACS. The objective of this prospective, multicenter, observational study is to define immune response and their relationship to the occurrence and progressive of ACS. METHODS: This is a multicenter, prospective, observational longitudinal cohort study. The primary outcome is the incidence of major adverse cardiovascular events (MACE) including in-stent restenosis, severe ventricular arrhythmia, heart failure, recurrent angina pectoris, and sudden cardiac death, and stroke one year later after ACS. Demographic characteristics, clinical data, treatments, and outcomes are collected by local investigators. Furthermore, freshly processed samples will be stained and assessed by flow cytometry. The expression of S100A4, CD47, SIRPα and Tim-3 on monocytes, macrophages and T cells in ACS patients were collected. FOLLOW-UP: during hospitalization, 3, 6 and 12 months after discharge. DISCUSSION: It is expected that this study will reveal the possible targets to improve the prognosis or prevent from occurrence of MACE in ACS patients. Since it's a multicenter study, the enrollment rate of participants will be accelerated and it can ensure that the collected data are more symbolic and improve the richness and credibility of the test basis. ETHICS AND DISSEMINATION: This study has been registered in Chinese Clinical Trial Registry Center. Ethical approval was obtained from the Affiliated Hospital of Guizhou Medical University. The dissemination will occur through the publication of articles in international peer-reviewed journals. TRIAL REGISTRATION: Chinese Clinical Trial Registry: ChiCTR2200066382.

Hydrogen Storage Performance of Mg/MgH2 and Its Improvement Measures: Research Progress and Trends.

Due to its high hydrogen storage efficiency and safety, Mg/MgH2 stands out from many solid hydrogen storage materials and is considered as one of the most promising solid hydrogen storage materials. However, thermodynamic/kinetic deficiencies of the performance of Mg/MgH2 limit its practical applications for which a series of improvements have been carried out by scholars. This paper summarizes, analyzes and organizes the current research status of the hydrogen storage performance of Mg/MgH2 and its improvement measures, discusses in detail the hot studies on improving the hydrogen storage performance of Mg/MgH2 (improvement measures, such as alloying treatment, nano-treatment and catalyst doping), and focuses on the discussion and in-depth analysis of the catalytic effects and mechanisms of various metal-based catalysts on the kinetic and cyclic performance of Mg/MgH2. Finally, the challenges and opportunities faced by Mg/MgH2 are discussed, and strategies to improve its hydrogen storage performance are proposed to provide ideas and help for the next research in Mg/MgH2 and the whole field of hydrogen storage.

Study on the cyclic adsorption performance of biomass composite membrane for Hg(II).

Salix psammophila wood flour /polyvinyl alcohol hydrogel composite membrane (SPPM) with high adsorption capacity and good cycle adsorption performance was prepared by wet spinning technology. The SPPM was characterised by the scanning electron microscope (SEM), specific surface area test (BET), energy dispersive spectrum (EDS) thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR), and x-ray photoelectron spectroscopy (XPS). The results showed that the surface of SPPM is rough and porous, with good pore structure and thermal stability, and mercury ions (Hg(II)) have been successfully adsorbed on SPPM. At the same time, the effects of adsorption conditions (Hg(II) initial concentration, pH, adsorption time, and temperature) on the adsorption performance of SPPM were studied. Results from the adsorption experiment showed that the adsorption capacity of SPPM for Hg(II) can reach 426 mg/g. After four adsorption and desorption experiments, the adsorption capacity can reach 375 mg/g, which indicates that SPPM has good cycle adsorption performance. The adsorption kinetics was better described by the Pseudo-second-order kinetic, and their adsorption isotherms were fitted for the Langmuir model. The obtained results showed that SPPM is an available, economical adsorbent and was found suitable for removing Hg(II) from an aqueous solution.

Anti-infective bile acids bind and inactivate a Salmonella virulence regulator.

Bile acids are prominent host and microbiota metabolites that modulate host immunity and microbial pathogenesis. However, the mechanisms by which bile acids suppress microbial virulence are not clear. To identify the direct protein targets of bile acids in bacterial pathogens, we performed activity-guided chemical proteomic studies. In Salmonella enterica serovar Typhimurium, chenodeoxycholic acid (CDCA) most effectively inhibited the expression of virulence genes and invasion of epithelial cells and interacted with many proteins. Notably, we discovered that CDCA can directly bind and inhibit the function of HilD, an important transcriptional regulator of S. Typhimurium virulence and pathogenesis. Our characterization of bile acid-resistant HilD mutants in vitro and in S. Typhimurium infection models suggests that HilD is one of the key protein targets of anti-infective bile acids. This study highlights the utility of chemical proteomics to identify the direct protein targets of microbiota metabolites for mechanistic studies in bacterial pathogens.

Chemical proteomic analysis of bile acid-protein targets in Enterococcus faecium.

Bile acids are important gut microbiota metabolites that regulate both host and microbial functions. To identify the direct protein targets of bile acids in Enterococcus, we synthesized and validated the activity of a lithocholic acid (LCA) photoaffinity reporter, x-alk-LCA-3. Chemical proteomics of x-alk-LCA-3 in E. faecium Com15 reveals many candidate LCA-interacting proteins, which are involved in cell well synthesis, transcriptional regulation and metabolism. To validate the utility of bile acid photoaffinity labeling, we characterized a putative bile salt hydrolase (BSH) crosslinked by x-alk-LCA-3, and demonstrated that this BSH was effective in converting taurolithocholic acid (TLCA) to LCA in E. faecium and in vitro. Chemical proteomics should afford new opportunities to characterize bile acid-protein targets and mechanisms of action in the future.

Acquired von Willebrand Syndrome Secondary to Normally Functioning Mechanical Aortic Valve and High-Output Cardiac State.

Acquired von Willebrand syndrome (AVWS) is caused by an acquired deficiency of von Willebrand factor (VWF), a multimeric protein required for primary hemostasis. For patients with heart valve diseases, high gradient across the malfunctioning valves could cause elevated shear stress and damage the most effective large VWF, eventually resulting in AVWS. However, AVWS has not been reported in association with normally functioning mechanical valves. Herein, we reported a 74-year-old female who suffered from recurrent gastrointestinal bleeding with a history of mechanical aortic and mitral valve replacement. This patient's function/antigen ratio of VWF was decreased and gel electrophoresis revealed the loss of large VWF, which confirmed the diagnosis of AVWS. Echocardiogram showed that the function of the prostheses was normal. However, the gradient across aortic valve was increased due to a high cardiac state which is secondary to chronic anemia, resulting in the disruption of large VWF multimers and exacerbation of gastrointestinal (GI) bleeding. After managing the patient's anemia with transfusion, the gradient across the aortic valve had improved, with the resolution of GI bleeding. This is the first case report of AVWS that is associated with a normally functioning mechanical valve. AVWS should be considered one of the differential diagnoses if patients present with unexplained GI bleeding on the background of having prosthetic heart valves. The management of the underlying condition is essential.

Integrated energy system optimal scheduling considering the comprehensive and flexible operation mode of pumping storage.

The integrated energy system (IES) optimal scheduling under the comprehensive flexible operation mode of pumping storage is considered. This system is conducive to the promotion of the accommodation of wind and solar energy and can meet the water, electricity and heat needs of coastal areas far away from the energy center. In this study, the joint dispatch between double pumped storage power stations is used to accommodate wind and solar energy better and smooth their fluctuations on the grid. Through the scheduling of water between the high and low reservoirs of double pumped storage power stations and the reservoir of the seawater desalination plant, the impact of storage capacity constraints on pumped storage power plants is reduced. Moreover, the objective function to build the IES optimization scheduling model is to achieve minimum economic cost. The results reveal that the integrated energy system accommodates all wind energy and solar energy. As such, the system increases the average working time of the pumped storage unit by 1.9 hours and reduces the economic cost by 31.50%. Based on the simulation results, the model can enhance the accommodation capability of wind energy and solar energy and improve the system economy.

Identification of a Bile Acid-Binding Transcription Factor in Clostridioides difficile Using Chemical Proteomics.

Clostridioides difficile is a Gram-positive anaerobic bacterium that is the leading cause of hospital-acquired gastroenteritis in the US. In the gut milieu, C. difficile encounters microbiota-derived, growth-inhibiting bile acids that are thought to be a significant mechanism of colonization resistance. While the levels of certain bile acids in the gut correlate with susceptibility to C. difficile infection, their molecular targets in C. difficile remain unknown. In this study, we sought to use chemical proteomics to identify bile acid-interacting proteins in C. difficile. Using photoaffinity bile acid probes and chemical proteomics, we identified a previously uncharacterized MerR family protein, CD3583 (now BapR), as a putative bile acid-sensing transcription regulator. Our data indicate that BapR specifically binds to and is stabilized by lithocholic acid (LCA) in C. difficile. Although loss of BapR did not affect C. difficile's sensitivity to LCA, ΔbapR cells elongated more in the presence of LCA compared to wild-type cells. Transcriptomics revealed that BapR regulates several gene clusters, with the expression of the mdeA-cd3573 locus being specifically de-repressed in the presence of LCA in a BapR-dependent manner. Electrophoretic mobility shift assays revealed that BapR directly binds to the mdeA promoter region. Because mdeA is involved in amino acid-related sulfur metabolism and the mdeA-cd3573 locus encodes putative transporters, we propose that BapR senses a gastrointestinal tract-specific small molecule, LCA, as an environmental cue for metabolic adaptation.

An Novel Optimization Model for Ideological and Political Course in Colleges under the Environment of BD Mining Technology.

The big data (BD) era and pertinent computer science, pedagogy, and educational psychology knowledge are the foundations of this essay, based on the idea of the holistic development of human beings, the IPE (Ideological and Political Education) carrier theory, the new idea of educational development, and the strategy of strengthening the nation through education; the challenges IPECU (Ideological and political education in Colleges and Universities) faces and its path toward optimization are discussed relatively in detail in this paper, which conforms to the context of mega data thinking. The influence of IPECU's subject, object, and educational effect is discussed in this paper, along with tips for how to improve and innovate IPECU in the context of big data. In addition, it is noted that in the age of mega data, we must not only bravely take on challenges, but also actively seize opportunities if we are to realize the innovative and optimized development of IPECU. Moreover, the definitions of mega data and big data prediction function are provided in this paper. IPE can be used with the big data prediction function, which is further explored in this article. In order to realize the innovation of IPE mode in universities, this paper aims to encourage the integration and development of IPE and big data in academic settings.

Rhodotron and rotating target: A solution towards micro-spot for high energy and high dose rate bremsstrahlung sources.

High energy over MeV bremsstrahlung sources that employ normal conducting radio frequency linear accelerators have expanding applications in industrial computerized tomography (CT) for non-destructive inspection and evaluation. The X-ray spot size that mainly affects the imaging quality is yet limited by the electron beam width in the high resolution CT systems. In a short exposure time, high beam power is required to generate sufficient photons to improve the signal to noise ratio of imaging. However, with ∼kW level of average beam power these linear accelerators usually have a beam spot size over 1 mm since the temperature rising due to the beam energy deposition in the target should be far below its melting point. We propose a concept of using a Rhodotron-based accelerator to provide high power electron beams in a long duration pulse and a rotating target to mitigate the overheating issue, such that the gap between micro-spot and high dose rate can be bridged in the high energy bremsstrahlung sources. This article presents an in-depth simulation work to discuss and evaluate this scheme of X-ray source. The simulations of beam dynamics in the accelerator and bremsstrahlung process in the target predict the generated X-rays with a spot size as small as 68 µm at full-width half-maximum and a dose rate as high as 4700 cGy/min from a 9 MeV electron beam interacting with a 1 mm thickness tantalum target. Further thermal analysis in the rotating target indicates a significant improvement of beam power handling in comparison with the conventional stationary one.

Ni3Fe/BC nanocatalysts based on biomass charcoal self-reduction achieves excellent hydrogen storage performance of MgH2.

Bimetallic catalysts offer unique advantages for improving the hydrogen storage performance of MgH2. Herein, Ni3Fe/BC nanocatalysts were prepared via a simple solid phase reduction method using a low-cost biomass charcoal (BC) material as the carrier. The onset temperature of hydrogen release for the MgH2 + 10 wt% Ni3Fe/BC composite was 184.5 °C, which is 155.5 °C lower than that of pure MgH2. The dehydrogenated composite starts to absorb hydrogen at as low as 30 °C and is able to absorb 5.35 wt% of H2 within 10 min under 3 MPa hydrogen pressure at 150 °C. In comparison to pure MgH2, the apparent activation energies of dehydrogenation and rehydrogenation of MgH2 + 10 wt% Ni3Fe/BC were reduced by 52.89 kJ mol-1 and 23.28 kJ mol-1, respectively. The hydrogen storage capacity of the composite was maintained in 20 de/rehydrogenation cycles, indicating a good cycling stability. X-Ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray energy dispersive spectroscopy (EDS) characterization reveal that the in situ formation of multiphases Mg2Ni and Fe catalysts during the hydrogen uptake and release reaction and the transformation of Mg2Ni/Mg2NiH4 together contribute to the superior hydrogen adsorption and desorption performance of MgH2.

Regulation of Kinetic Properties of Chemical Hydrogen Absorption and Desorption by Cubic K2MoO4 on Magnesium Hydride.

Transition metal catalysts are particularly effective in improving the kinetics of the reversible hydrogen storage reaction for light metal hydrides. Herein, K2MoO4 microrods were prepared using a simple evaporative crystallization method, and it was confirmed that the kinetic properties of magnesium hydride could be adjusted by doping cubic K2MoO4 into MgH2. Its unique cubic structure forms new species in the process of hydrogen absorption and desorption, which shows excellent catalytic activity in the process of hydrogen storage in MgH2. The dissociation and adsorption time of hydrogen is related to the amount of K2MoO4. Generally speaking, the more K2MoO4, the faster the kinetic performance and the shorter the time used. According to the experimental results, the initial dehydrogenation temperature of MgH2 + 10 wt% K2MoO4 composite is 250 °C, which is about 110 °C lower than that of As-received MgH2. At 320 °C, almost all dehydrogenation was completed within 11 min. In the temperature rise hydrogen absorption test, the composite system can start to absorb hydrogen at about 70 °C. At 200 °C and 3 MPa hydrogen pressure, 5.5 wt% H2 can be absorbed within 20 min. In addition, the activation energy of hydrogen absorption and dehydrogenation of the composite system decreased by 14.8 kJ/mol and 26.54 kJ/mol, respectively, compared to pure MgH2. In the cycle-stability test of the composite system, the hydrogen storage capacity of MgH2 can still reach more than 92% after the end of the 10th cycle, and the hydrogen storage capacity only decreases by about 0.49 wt%. The synergistic effect among the new species MgO, MgMo2O7, and KH generated in situ during the reaction may help to enhance the absorption and dissociation of H2 on the Mg/MgH2 surface and improve the kinetics of MgH2 for absorption and dehydrogenation.