Modulating Porous Carbon Electrocatalyst for Efficient Water Splitting

The increasing public issues about the energy crisis urge the development of sustainable energy as alternatives to replace the fossil fuels. Considering the energy regeneration and environment friendly, hydrogen possesses the potential to meet the criterion of renewable and clean energies. H2 can be produced in an electrochemical water electrolyser by cathodic hydrogen evolution reaction (HER), coupled with anodic oxygen evolution reaction (OER). The kinetic barrier of both reactions require efficient electrocatalysts. However, the benchmarking electrocatalysts for HER or OER are based on precious metals, such as Pt or Ir, their high cost greatly hinders the practical H2 production from water electrolyser in an economic manner. Thus, the search of in-expensive but efficient HER and OER electrocatalysts is imminent. Among various candidature materials, low cost and high conductive carbon based nanomaterials have attracted intensive attention. Through heteroatom doping, the inert carbon nanomaterials can be activated to show promising catalytic activity. In this study, nitrogen doped nanoporous carbon electrocatalysts were obtained from thermal pyrolysis of a zinc based metal-organic framework. Cathodic treatment is successfully applied to achieve systematic modulation of the type and surface functionalities. The modulated electrocatalysts show high activity and good stability towards hydrogen and oxygen evolution in various electrolyte. Strong correlation between catalytic performance and surface chemical properties of these carbon electrocatalysts has been found. My work here paves a new way to design metal free carbon electrocatalysts for future green energy applications

Engineering active sites for advanced room-temperature Na-S batteries

Room temperature sodium-sulfur (RT Na-S) batteries attract many attentions since they endow many overwhelming merits, for instances, resources abundances of S and Na, high theoretical capacity of S (1672 mAh g-1), non-toxicity, and cost-efficiency. Nevertheless, the Na-S batteries are often restrained for their poor cycling performance and inferior Coulombic efficiency, which result from the sodium polysulfide (NaPSs) dissolution and the sluggish kinetics reactions. These issues always result in fast active materials loss and rapid cycling decay. To overcome these challenges, preventing the reactions between NaPSs species on the cathode, long-chain NaPSs dissolution and improving the kinetics reaction are extremely important. Therefore, it is very important to prepare the novel hosts with proper pore structure and enough surface area to embed the active materials and provide enough volume for S expansion during the cell working. Moreover, by decoration of abundant electrocatalytic active sites, the hosts can efficiently trap and catalyze NaPSs intermediates, which is in favour of construction of RT Na-S batteries with excellent performance. In this doctoral work, three different works are investigated, including single atomic Fe grown on nanospheres (S@Fe-SA-PNC), a general strategy to fabricate single atomic sites decorated on carbon nanospheres (S@Metal-SA-PNC, Metal= Mn, Co, Ni, Cu, Sn, Pb), as well as FeS nanoparticles decorated carbon nanotubes (S@FeS-CNT)

Effect of Notch on Strain Rate Concentration Factor of 304 Stainless Steel Bar

In this study, the notch effect of different types of 304 stainless steel rod notch is studied because of the problem of difficulty in measuring the notch root strain of 304 rod stainless steel, and the parameters of the annular notch root are analyzed. The notch angle, notch depth, and notch root radius are the main parameters of the stress field affecting the annular notch, and the mathematical expression of the strain rate concentration factor is derived. In order to verify the accuracy of the theory, the mechanical model of 304 stainless steel bar is established by finite element and numerical simulation calculation. The results show that the theoretical and finite elements have a high degree of agreement. When the notch angle increases, both theoretical and finite elements show a downward trend. When the notch depth of 304 stainless steel bar increases, both theoretical and numerical simulations show an increasing trend. The notch root radius of 304 stainless steel bar increases with decreasing numerical simulation

Reliability Evaluation of Photovoltaic System Considering Inverter Thermal Characteristics

The reliable operation of photovoltaic (PV) power generation systems is related to the security and stability of the power grid and is the focus of current research. At present, the reliability evaluation of PV power generation systems is mostly calculated by applying the standard failure rate of each component, ignoring the impact of thermal environment changes on the failure rate. This paper will use the fault tree theory to establish the reliability assessment method of PV power plants, model the PV power plants working in the variable environment through the hardware-in-the-loop simulation system, and analyze the influence of the thermal characteristics of the inverter’s key components on the reliability of the PV power plant. Studies have shown that the overall reliability of bus capacitors, inverters, and PV power plants is reduced by 18.4%, 30%, and 18.7%, respectively, compared to when the thermal characteristics of bus capacitors are not considered. It can be seen that thermal attenuation has a great influence on the reliability of the PV power generation system

Self-assembling RuO2 nanogranulates with few carbon layers as an interconnected nanoporous structure for lithium-oxygen batteries

Electrocatalysis for cathodic oxygen is of great significance for achieving high-performance lithium-oxygen batteries. Herein, we report a facile and green method to prepare an interconnected nanoporous three-dimensional (3D) architecture, which is composed of RuO2 nanogranulates coated with few layers of carbon. The as-prepared 3D nanoporous RuO2@C nanostructure can demonstrate a high initial specific discharge capacity of 4000 mA h g-1 with high round-trip efficiency of 95%. Meanwhile, the nanoporous RuO2@C could achieve stable cycling performance with a fixed capacity of 1500 mA h g-1 over 100 cycles. The terminal discharge and charge potentials of nanoporous RuO2@C are well maintained with minor potential variation of 0.14 and 0.13 V at the 100th cycle, respectively. In addition, the formation of discharge products is monitored by using in situ high-energy synchrotron X-ray diffraction (XRD)

Interface challenges and optimization strategies for aqueous zinc-ion batteries

Aqueous zinc-ion batteries have advantages over lithium-ion batteries, such as low cost, and good safety. However, their development is currently facing several challenges. One of the main critical challenges is their poor electrode–electrolyte interface. Addressing this requires understanding the physics and chemistry at the electrode–electrolyte interface, including the cathode-electrolyte interface and anode-electrolyte interface. This review first identifies and analyses the interfacial challenges of aqueous zinc-ion batteries. Then, it discusses the design strategies for addressing the defined interfacial issues from the perspectives of electrolyte optimization, electrode modification, and separator improvement. Finally, it provides corrective recommendations and strategies for the rational design of electrode–electrolyte interface in aqueous zinc-ion batteries towards their high-performance and reliable energy storage

Fluctuating Behavior and Influential Factors in the Performance of the QuantiFERON-TB Gold In-Tube Assay in the Diagnosis of Tuberculosis.

The QuantiFERON-TB Gold In-Tube (QFT-GIT) is a newly developed but widely used interferon-γ release assay for diagnosing tuberculosis (TB). However, research has not determined whether age or the use of an immune suppressive or anti-TB treatment influences this assay's ability to detect TB. We assessed the QFT-GIT diagnostic performance for active tuberculosis (ATB) in children and adults in an endemic country and explored the effects of glucocorticoids and anti-TB therapy on the diagnostic value of the QFT-GIT.A total of 60 children and 212 adults with suspected ATB were evaluated with the QFT-GIT. The association between the QFT-GIT diagnostic value and pretreatment factors was qualitatively and quantitatively assessed.The sensitivity of the QFT-GIT was 83.9% (95% CI 66.3%-94.6%) in children, and 73.7% (95% CI 57.8%-85.2%) in adults. Glucocorticoids affected the mitogen-stimulated response in both children and adults. In subjects undergoing glucocorticoid pretreatment, 25.0% of the children presented with false-negative QFT-GIT results, 28.6% of adults presented with indeterminate results. For subjects pre-treated with anti-TB drugs, 44.4% presented with false-negative QFT-GIT results.The QFT-GIT has higher sensitivity and specificity in children than adults. Glucocorticoid treatment negatively impacts the diagnostic value of the QFT-GIT in all age groups. Anti-TB treatment decreases the sensitivity of the QFT-GIT. Therefore, we recommend that the QFT-GIT assay be performed before TB-specific treatment is initiated and the test should not be used on people undergoing immunosuppression treatment, regardless of their age. A quantitative analysis of the QFT-GIT could be useful for assessing and monitoring TB-specific and non-specific immunity during conversion of the disease

Reappraisal of hard carbon anodes for practical lithium/sodium-ion batteries from the perspective of full-cell matters

Hard carbon (HC) has the potential to be a viable commercial anode material in both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, current battery performance evaluation methods based on half-cells are insufficient for accurately assessing the performance of HC anodes due to their ultra-low discharge voltage windows. To develop the next-generation of large-scale rechargeable batteries, it is necessary to examine reported HC materials from a full-cell perspective. This review emphasizes the importance of full-cell validation and provides a comprehensive overview of HC anodes - including their history, fundamentals, carbon chemistry induced by temperature, microstructure correlation with electrochemical performance, and debates surrounding lithium/sodium-ion storage mechanisms. Additionally, this review highlights various optimization strategies and suggests potential areas for future application of HC-based lithium-ion batteries (HC-LIBs) and HC-based sodium-ion batteries (HC-SIBs). Furthermore, different challenges and strategies that need to be addressed are presented in the hope of providing inspiration and guidance for the commercialization of HC anodes