Polysulfide-mediated solvation shell reorganization for fast Li+ transfer probed by in-situ sum frequency generation spectroscopy

Understanding of interfacial Li$^+$ solvation shell structures and dynamic evolution at the electrode/electrolyte interface is requisite for developing high-energy-density Li batteries. Herein, the reorganization of Li$^+$ solvation shell at the sulfur/electrolyte interface along with the presence of a trace amount of lithium polysulfides is verified by in-situ sum frequency generation (SFG) spectroscopy together with density functional theory (DFT) calculations. Both the spectroelectrochemical and DFT calculation results reveal a strongly competitive anion adsorption of the polysulfide anion additive against the pristine electrolyte anion on the sulfur cathode surface, reorganizing the interfacial local solvation shell structure facilitating rapid Li ion transfer and conduction. Meanwhile, the evolution of the SFG signals along with the discharging/charging cycle exhibits improved reversibility, indicating the transformation of the inner Helmholtz plane layer into a stable molecular-layer polysulfide interphase rather than a dynamic diffusion layer. Consequently, applications in practical Li-S batteries reveal the capacity and cycling stability of the corresponding cells are significantly enhanced. Our work provides a methodology using in-situ SFG for probing solvation reorganization of charge carriers at electrochemical interfaces

Mitochondrial DNA Evidence for a Diversified Origin of Workers Building Mausoleum for First Emperor of China

Variant studies on ancient DNA have attempted to reveal individual origin. Here, based on cloning sequencing and polymerase chain reaction-restriction fragment length polymorphisms, we analyzed polymorphisms in the first hypervariable region and coding regions of mitochondrial DNA of 19 human bone remains which were excavated from a tomb near the Terra Cotta Warriors and dated some 2,200 years before present. With the aim of shedding light on origins of these samples who were supposed to be workers building the mausoleum for the First Emperor of China, we compared them with 2,164 mtDNA profiles from 32 contemporary Chinese populations at both population and individual levels. Our results showed that mausoleum-building workers may be derived from very diverse sources of origin

Waste Heat Recovery from High-Temperature Blast Furnace Slag Particles

187-192Heat transfer models for packed bed, moving bed and fluidized bed to recover thermal energy from high temperature slag particles were established. The sticking point, which blocked the application and development of recovering thermal energy from high temperature slag particles by air, was addressed. The results showed that the packed bed, moving bed and fluidized bed were not suitable for recycling thermal energy from slag particles with small diameter, high temperature and flowrate. Based on the problem mentioned above, a technique of thermal energy recovery from high temperature slag particles using gravity bed waste heat boiler was exploited. The waste heat boiler can produce steam obtained in the upper part of the gravity bed boiler and the heat recovery rate can reach as much as 91%. As a consequence, it is possible to recycle thermal energy from high-temperature slag particles using a gravity bed waste heat boiler to produce steam

Combining theory and experiment analysis in molten BFS waste heat recovery integrated with coal gasification

A novel method that a heat recovery system from blast furnace slag integrated with coal gasification reaction to generate syngas was proposed. The motion characteristic and critical velocity of the coal particles in the molten slag were estimated. Meanwhile, the effects of temperature and steam to coal ratio on coal gasification product distribution and gas characterization were discussed. The results showed that the coal particles (~75 μm) would break through the bondage of bubbles and transport into molten slag when the velocity of coal particles were above 4.20 m·s-1 and the diameter of bubbles were less 6 mm. There had higher gasification efficiency, gas yield production and H2 production by this method. The results suggested that the optimal conditions for slag waste heat recovery were achieved at 1623 K and steam to coal ratio of 2.0. Under these conditions, the gas yield and carbon conversion reached 133.48 mol·kg-1 and 97.81%, respectively. The proposed method enhanced the coal gasification efficiency and recovered the high quality of molten blast furnace slag waste heat effectively, and had important guidance for industrial manufacture

Polyoxometalate-Embedded Metal–Organic Framework as an Efficient Copper-Based Monooxygenase for C(sp³)–H Bond Oxidation via Multiphoton Excitation

The complex and precise structure of natural monooxygenases makes it difficult to clone their structure and activity, and the reported artificial copper-based monooxygenase catalysts for the oxidation of inert C(sp3)–H bonds exhibit limited catalytic activities. Inspired by monooxygenases, we report a metal–organic framework (SiW12@CuMOF-1) comprising a binuclear copper HAT catalyst, photosensitizing nicotinamide adenine dinucleotide (NAD+) mimic bridging ligand, and embedded polyoxometalate. SiW12@CuMOF-1 accelerates the oxidative dehydrogenation of 3,5-DTBC with a catalytic efficiency comparable to that of natural polyphenol oxidase. In the presence of pyridine hydrochloride, irradiation of SiW12@CuMOF-1 afforded the highly active chlorine radical and CuI species via a ligand-to-metal charge transfer process. The chlorine radical abstracts a hydrogen atom selectively from C(sp3)–H bonds to generate the radical intermediate. The CuI species interacted with the active oxygen species 1O2 that formed from the photoinduced energy transfer from the excited state of the NAD+ mimics, giving the active oxygen species O2•– for further oxidization. The well-modified binuclear copper sites cleave the O–O bond to give the final products selectively. Meanwhile, the embedded polyoxometalates interacted with the alcohol substrates via hydrogen bonding interactions to help the catalytic conversion with high efficiency. The well-defined structural characters, the finely modified catalytic properties, and the sustainable multiphoton excitation photocatalytic processes provide a new avenue to develop robust artificial enzymes with uniform active sites and improved catalytic performances

Polyoxometalate-Embedded Metal–Organic Framework as an Efficient Copper-Based Monooxygenase for C(sp³)–H Bond Oxidation via Multiphoton Excitation

The complex and precise structure of natural monooxygenases makes it difficult to clone their structure and activity, and the reported artificial copper-based monooxygenase catalysts for the oxidation of inert C(sp3)–H bonds exhibit limited catalytic activities. Inspired by monooxygenases, we report a metal–organic framework (SiW12@CuMOF-1) comprising a binuclear copper HAT catalyst, photosensitizing nicotinamide adenine dinucleotide (NAD+) mimic bridging ligand, and embedded polyoxometalate. SiW12@CuMOF-1 accelerates the oxidative dehydrogenation of 3,5-DTBC with a catalytic efficiency comparable to that of natural polyphenol oxidase. In the presence of pyridine hydrochloride, irradiation of SiW12@CuMOF-1 afforded the highly active chlorine radical and CuI species via a ligand-to-metal charge transfer process. The chlorine radical abstracts a hydrogen atom selectively from C(sp3)–H bonds to generate the radical intermediate. The CuI species interacted with the active oxygen species 1O2 that formed from the photoinduced energy transfer from the excited state of the NAD+ mimics, giving the active oxygen species O2•– for further oxidization. The well-modified binuclear copper sites cleave the O–O bond to give the final products selectively. Meanwhile, the embedded polyoxometalates interacted with the alcohol substrates via hydrogen bonding interactions to help the catalytic conversion with high efficiency. The well-defined structural characters, the finely modified catalytic properties, and the sustainable multiphoton excitation photocatalytic processes provide a new avenue to develop robust artificial enzymes with uniform active sites and improved catalytic performances