synthesis-metal-nanoparticles-supported-on-carbon-nanotube-with-doped

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production

A method for facile synthesis of nanostructured catalysts supported on carbon nanotubes with atomically dispersed cobalt and nitrogen dopant is presented ...

Technological and Higher Education Institute of Hong Kong (THEi)

For the first time, two dimensional (2D) rectangular Co3O4 with micro-/nanoarchitectures is successfully synthesized by a facile hydrothermal treatment with the assistance of poly(diallyldimethylammonium chloride) (PDDA). Owing to the strong electrostatic interaction, positively charged PDDA molecules are considered as structure directing agents and play a crucial role in the formation of the unique 2D rectangular structure. Material characterization suggests that rectangular Co3O4 is typically endowed with a side length of 3-5 μm and a thickness of around 85 nm, and is composed of numerous interconnected nanocrystals about 15 nm in size. The interconnected nanocrystals provide few trap numbers for the electron transport process and contribute to the mesoporous structure with an average pore size of 18 nm. Thus, the distinctive micro-/nanoarchitectures effectively address the formidable challenges of Co3O4-based anode materials, highly favourable for enhancing lithium ion diffusion, improving electron transport pathways and alleviating volume variation during charge-discharge processes. When rectangular Co3O4 (FST-1) is evaluated as anode material for lithium ion batteries, a high reversible capacity of 1076.9 mA h g(-1) and an excellent first cycle Coulombic efficiency of 88.6% are achieved at a current density of 500 mA g(-1), thus delivering a capacity retention of nearly 100% after 100 cycles. Moreover, when tested at current densities as high as 1000 mA g(-1) and 2000 mA g(-1) for 100 cycles, lithium storage capacities can still be retained at 1020.2 mA h g(-1) and 616.4 mA h g(-1), respectively. Interestingly, by simply varying the reaction conditions or types of positively charged polymers, the polyelectrolyte-assisted hydrothermal route can be successfully extended to synthesize other novel micro-/nanoarchitectures, such as straw-tied-like and urchin-like structures, demonstrating great potential in developing next-generation anode materials for high performance lithium ion batteries. 

Rectangular Co3O4 with micro-/nanoarchitectures: charge-driven PDDA-assisted synthesis and excellent lithium storage performance.

Sewage sludge is an inevitable byproduct from municipal wastewater treatment processes and conversion of sewage sludge into high value-added biochar is an effective strategy for resource utilization of sewage sludge. The characterization on P speciation is important to control the practical applications and environmental behavior of the sewage sludge and its derived biochar. The mobility and bioavailability of P is closely related to its speciation, but knowledge gap in P speciation is still existed which needs to be narrowed by a systematic study including existing experimental methods and techniques as well as theoretical prediction. To achieve a comprehensive understanding of P speciation, this study conducted a series of research combining conventional fractionation of P with consideration of major concomitant elements (Al, Ca, Fe), advanced analytical techniques (solution and solid-state P nuclear magnetic resonance (NMR), X-ray diffraction (XRD)), and theoretical simulation with respect to solubility of major elements in different acid-base extractants. Results showed that Ca and Fe were dominantly extracted by HCl whereas P and Al were both NaOH- and HCl-soluble. Inorganic orthophosphates were detected as predominant molecular configurations of P from solution P NMR spectra, while the existence of calcium and aluminum orthophosphates was revealed by solid-state P NMR. Moreover, the poor-crystalline AlPO mineral was further evidenced by XRD patterns of the sewage sludge and biochar. Finally, a theoretical simulation of P-containing minerals was performed on the basis of results above, which suggested the existence of variscite/berlinite and amorphous Ca(PO) in the sludge and biochar. This study does not only explore the P speciation in the sewage sludge and its derived biochar, but also provides a methodology for further research on P speciation. Through the intensive study on the environmental behavior of P, this work might further contribute to the fundamental knowledge basis for the recycle of P during integrate waste management.

Phosphorus speciation in sewage sludge and the sludge-derived biochar by a combination of experimental methods and theoretical simulation.

Organic solid wastes (OSWs) should be regarded as valuable resources rather than dead-end landfill waste that causes public health and odor concerns. Anaerobic digestion (AD) is an ideal approach for managing organic solid waste issues and involves using a group of anaerobic microorganisms to transform OSWs into useful products. In this review, over 100 publications related to AD of OSWs have been compiled, discussed, and analyzed. A comprehensive analysis of the environmental and safety impacts of AD, its key environmental factors, co-digestion, and pretreatment, as well as the AD of OSWs by various anaerobic microbes uncovered by high throughput sequencing-based approaches, is presented. The purpose of this review is to provide an outline of the current knowledge of AD processes from a multi-angle perspective. A comprehensive understanding of AD of OSWs and genome-enabled biology development could be helpful for providing up-to-date knowledge of AD, developing it, overcoming its drawbacks and, ultimately, improving global waste control for more efficient environmental management. © 2018 Society of Chemical Industry.

A comprehensive review of anaerobic digestion of organic solid wastes in relation to microbial community and enhancement process.

In this study, hydrothermal synthesis of sea urchin-like NiCoO was successfully demonstrated by a versatile charge-driven self-assembly strategy using positively charged poly(diallydimethylammonium chloride) (PDDA) molecules. Physical characterizations implied that sea urchin-like microspheres of ~ 2.5 μm in size were formed by self-assembly of numerous nanoneedles with a typical dimension of ~ 100 nm in diameter. Electrochemical performance study confirmed that sea urchin-like NiCoO exhibited high reversible capacity of 663 mAh g after 100 cycles at current density of 100 mA g. Rate capability indicated that average capacities of 1085, 1048, 926, 642, 261, and 86 mAh g could be achieved at 100, 200, 500, 1000, 2000, and 3000 mA g, respectively. The excellent electrochemical performances were ascribed to the unique micro/nanostructure of sea urchin-like NiCoO, tailored by positively charged PDDA molecules. The proposed strategy has great potentials in the development of binary transition metal oxides with micro/nanostructures for electrochemical energy storage applications.

Article	Year
Rectangular Co3O4 with micro-/nanoarchitectures: charge-driven PDDA-assisted synthesis and excellent lithium storage performance. Physical chemistry chemical physics : PCCP\| PubMed ID: 26806116	2016
Phosphorus speciation in sewage sludge and the sludge-derived biochar by a combination of experimental methods and theoretical simulation. Water research\| PubMed ID: 29702376	2018
A comprehensive review of anaerobic digestion of organic solid wastes in relation to microbial community and enhancement process. Journal of the science of food and agriculture\| PubMed ID: 30144051	2019
Synthesis of Sea Urchin-Like NiCoO via Charge-Driven Self-Assembly Strategy for High-Performance Lithium-Ion Batteries. Nanoscale research letters\| PubMed ID: 30613904	2019

Xiao-Ying Lu

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