Recent Progress in Graphene-Based Electrocatalysts for Hydrogen Evolution Reaction

Hydrogen is regarded as a key renewable energy source to meet future energy demands. Moreover, graphene and its derivatives have many advantages, including high electronic conductivity, controllable morphology, and eco-friendliness, etc., which show great promise for electrocatalytic splitting of water to produce hydrogen. This review article highlights recent advances in the synthesis and the applications of graphene-based supported electrocatalysts in hydrogen evolution reaction (HER). Herein, powder-based and self-supporting three-dimensional (3D) electrocatalysts with doped or undoped heteroatom graphene are highlighted. Quantum dot catalysts such as carbon quantum dots, graphene quantum dots, and fullerenes are also included. Different strategies to tune and improve the structural properties and performance of HER electrocatalysts by defect engineering through synthetic approaches are discussed. The relationship between each graphene-based HER electrocatalyst is highlighted. Apart from HER electrocatalysis, the latest advances in water electrolysis by bifunctional oxygen evolution reaction (OER) and HER performed by multi-doped graphene-based electrocatalysts are also considered. This comprehensive review identifies rational strategies to direct the design and synthesis of high-performance graphene-based electrocatalysts for green and sustainable applications

A novel chopping current protection circuit for intrinsically safe power supply

For problems that traditional chopping current protection circuit had small cut-off current value and poor anti load impact ability, and needed additional recovery circuit or manual circuit after over-current fault, a novel chopping current protection circuit for intrinsically safe power supply was designed. The circuit adopts double parallel control structure, so as to improve reliability. The circuit can chop circuit rapidly under condition of load over flowing, and put into operation fast after fault with adjusted input point. Meanwhile, the circuit has low power consumption part, so as to reduce power loss under condition of light load or no-load. The experimental results show that the circuit can recover automatically after over-current fault with low load effect and strong load capacity

Effect of carbonation and foam content on CO2 foamed concrete behavior

Coal and electricity integration plays an important role in ensuring national energy security, but it still faces the challenge of carbon emission reduction. The development of in-situ CO2 sequestration and utilization technology for pithead power plants is an effective way to achieve low-carbon and efficient utilization of coal power. The preparation of foam concrete for mining using CO2 is a type of carbon capture, utilization, and storage technology featuring in-situ CO2 sequestration and utilization in pithead power plants and mine filling and sequestration. The purpose of this study is to evaluate the basic performance and carbon sequestration potential of Portland cement-based CO2 foam concrete (PC-CFC) as a mining material. In this study, PC-CFC was prepared through physical foaming and the carbonation pretreatment cement process. The influence of carbonation pretreatment time and CO2 foam content on density, strength, and carbon sequestration of PC-CFC was investigated. The experimental results showed that carbonation pretreatment could enhance the stability of CO2 foam in Portland cement and improve the CO2 foaming performance. With the extension of carbonation pretreatment time, the extend of dry density reduction decreases from 16.6% to 0.8%. A 60 min–90 min of carbonation pretreatment can achieve the best treatment performance. Carbonation pretreatment and CO2 foam can promote the degree of cement hydration, optimize the PC-CFC pore structure, and improve the compressive strength of PC-CFC. However, the PC-CFC material strength owing to the extended carbonation treatment time, which leads to well-developed vesicle distribution, has an overall decreasing trend. In addition, the 7 day (d) compressive strength of PC-CFC can reach more than 60% of the 28 d compressive strength, which has evident early strength characteristics. Extending the carbonation pretreatment time and CO2 foam content increased the PC-CFC carbon sequestration that ranged from 61.0 kg/ton to 85.7 kg/ton. The dry density of the PC-CFC material was significantly and positively correlated to the 28 d compressive strength and negatively correlated to the amount of carbon sequestration. In the case in which the best carbon sequestration effects is achieved, a single filling of the working face end can store ∼3929.31 kg of CO2; in the most economical condition, it can store ∼3642.79 kg of CO2. The conducted research provides new ideas for the low-carbon and green development of coal and electricity integration

Genomic characteristics and comparative genomics analysis of Penicillium chrysogenum KF-25

BACKGROUND: Penicillium chrysogenum has been used in producing penicillin and derived β-lactam antibiotics for many years. Although the genome of the mutant strain P. chrysogenum Wisconsin 54-1255 has already been sequenced, the versatility and genetic diversity of this species still needs to be intensively studied. In this study, the genome of the wild-type P. chrysogenum strain KF-25, which has high activity against Ustilaginoidea virens, was sequenced and characterized. RESULTS: The genome of KF-25 was about 29.9 Mb in size and contained 9,804 putative open reading frames (orfs). Thirteen genes were predicted to encode two-component system proteins, of which six were putatively involved in osmolarity adaption. There were 33 putative secondary metabolism pathways and numerous genes that were essential in metabolite biosynthesis. Several P. chrysogenum virus untranslated region sequences were found in the KF-25 genome, suggesting that there might be a relationship between the virus and P. chrysogenum in evolution. Comparative genome analysis showed that the genomes of KF-25 and Wisconsin 54-1255 were highly similar, except that KF-25 was 2.3 Mb smaller. Three hundred and fifty-five KF-25 specific genes were found and the biological functions of the proteins encoded by these genes were mainly unknown (232, representing 65%), except for some orfs encoding proteins with predicted functions in transport, metabolism, and signal transduction. Numerous KF-25-specific genes were found to be associated with the pathogenicity and virulence of the strains, which were identical to those of wild-type P. chrysogenum NRRL 1951. CONCLUSION: Genome sequencing and comparative analysis are helpful in further understanding the biology, evolution, and environment adaption of P. chrysogenum, and provide a new tool for identifying further functional metabolites

Selective laser sintering of functionalized carbon nanotubes and inorganic fullerene-like tungsten disulfide reinforced polyamide 12 nanocomposites with excellent fire safety and mechanical properties

More effective and safe fire prevention solutions for polymer derivatives are necessary to address rising environmental and health concerns. In this study, the novel and simple chemically modified multi-walled carbon nanotubes (H-CNT) and PEGylated inorganic fullerene tungsten sulphide (P-IF-WS2) reinforced PA12 nanocomposites are synergistically prepared via selective laser sintering (SLS). The PA12/H-CNT/IF-WS2 nanocomposites show a wider sintering window than blank PA12. The formed hydrogen bond network of inter-chain contacts and compatibility in PA12/H-CNT/P-IF-WS2 matrix is proved. Furthermore, a dense carbon layer is developed by further dehydrating the oxygen-rich functional groups on the surface of H-CNT and P-IF-WS2 during carbonization at high temperatures. The PA12/H-CNT/P-IF-WS2 nanocomposites fabricated by incorporating hydrogen and carbon bonds in the PA12-based nanocomposites demonstrate good fire safety, thermal, and mechanical properties. The significant reduction in total heat release (20.14%), peak heat release (38.9%), and total smoke emission (22.6%) showed the improved fire safety of PA12. The H-CNT and P-IF-WS2 nanofillers also enhanced the mechanical (tensile and dynamic mechanical) capabilities. This technique of introducing nano-additives to SLS samples changes offers a practical, long-lasting, and effective way to improve the flame retardancy of laser-sintered polymer nanocomposites

Zn/Co-ZIF reinforced sugarcane bagasse aerogel for highly efficient catalytic activation of peroxymonosulfate

Sugarcane bagasse is the main solid waste of sugar extraction industry. However, there are less eco-friendly treatment methods for this kind of waste material. Most of them have been burned and this is a challenge for effective utilization of sugarcane. Herein, Zn/Co-ZIF nanoparticles are loaded onto the aerogel obtained from bagasse cellulose by doping method to form pomegranate-like structure products, i.e., Zn/Co-ZIF@GEL. By simulating the pomegranate-biomimetic structure, the leaching of cobalt ions is suppressed and enhanced its catalytic activity. Also, Zn/Co-ZIF@GEL behaves outstanding peroxymonosulfate (PMS) activation reactivity to degrade Rhodamine B (RhB) with achieving 100% removal rate in 30 min with enhanced water stability. The outer wrapping of nanoparticles by aerogel exhibits excellent reusability and the removal rate remains above 92% after 4 cycles. X-ray photoelectron spectroscopy (XPS) verifies the electron transfer between the heterostructures of Zn and Co could ensure the catalyst continues to complete the redox cycle with synergistic effect. Electron paramagnetic resonance (EPR) further investigates the non-radical singlet oxygen is the predominant degradation pathway of RhB. This work provides a new strategy for improved bagasse derivate ZIF catalytic application

The Preparation of Acryloxyl Group Functionalized Siloxane Polymers and the Study of Their Ultra Violet Curing Properties

Polysiloxane with multiple acryloxyl groups at the terminal site of the polymer chain was synthesized by the condensation reaction between hydroxyl-terminated polysiloxane and acryloyl chloride and used to improve the cross-linking density of UV-curable silicone materials initiated from dual acryloxy-terminated symmetric polysiloxane or single acryloxy-terminated asymmetric polysiloxane with the mixture of Irgacure 1173 and Irgacure 184 at a mass ratio of 1:1 as the photoinitiator. The effects of factors such as initiator composition, UV irradiation time, structure, and molecular weight of linear dual acryloxy-terminated or single acryloxy-terminated asymmetric siloxane oligomers on the gelation yield, thermal properties, water absorption, and water contact angle of UV-cured film were investigated. The synthesized cross-linking density modifier can be copolymerized with acryloxy-functionalized linear polysiloxanes under the action of a photoinitiator to increase the cross-link density of UV-cured products effectively. Both linear dual acryloxy-terminated or single acryloxy-terminated asymmetric siloxane oligomers can be copolymerized with cross-link density modifiers within 20 s of UV irradiation. The gelation yields of the UV-cured products obtained from the dual acryloxy-terminated siloxane oligomers were greater than 85%, and their surface water contact angles increased from 72.8° to 95.9° as the molecular weight of the oligomers increased. The gelation yields of UV-cured products obtained from single acryloxy-terminated asymmetric siloxane oligomers were less than 80%, and their thermal stabilities were inferior to those obtained from the dual acryloxy-terminated siloxane oligomers. However, the water contact angles of UV-cured products obtained from these single acryloxy-terminated asymmetric siloxane oligomers were all greater than 90°

Establishment of a rapid detection method for plutella xylostella granulovirus based on qPCR

Plutella xylostella granulovirus (PlxyGV) biopesticide is an effective tool to control the long-term damage of Plutella xylostella (Linnaeus) to cruciferous vegetables. In China, PlxyGV can be produced on a large scale using host insects, and its products have been registered in 2008. In experiments and biopesticide production, the routine enumeration method of PlxyGV virus particles is to use the Petroff-Hausser counting chamber in dark field microscope. However, the accuracy and repeatability of granulovirus (GV) counting are affected due to the small particle size of GV occlusion bodies (OBs), the limitations of optical microscope, the judgment of different operators, host impurities, the addition of biological products. This limits the convenience of its production, product quality, trading and field application. Here we use PlxyGV as an example, the method based on Real-time fluorescence quantitative PCR (qPCR) was optimized from two aspects of sample treatment and specific primers design, which improved the repeatability and accuracy of absolute quantitative OBs of GV. This study provides basic information for accurate quantitative PlxyGV by qPCR method