Enhanced Redox Electrocatalysis in High‑Entropy Perovskite Fluorides by Tailoring d–p Hybridization

High-entropy catalysts featuring exceptional properties are,in no doubt,playing an increasingly significant role in aprotic lithium-oxygen batteries.Despite extensive effort devoted to tracing the origin of their unparalleled performance,the relationships between multiple active sites and reaction intermediates are still obscure.Here,enlightened by theoretical screening,we tailor a high-entropy perovskite fluoride(KCoMnNiMgZnF_(3)-HEC)with various active sites to overcome the limitations of conventional catalysts in redox process.The entropy effect modulates the d-band center and d orbital occupancy of active centers,which optimizes the d–p hybridization between catalytic sites and key intermediates,enabling a moderate adsorption of LiO_(2)and thus reinforcing the reaction kinetics.As a result,the Li–O2 battery with KCoMnNiMgZnF_(3)-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability,preceding majority of traditional catalysts reported.These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.

MOF-derived zinc manganese oxide nanosheets with valence-controllable composition for high-performance Li storage

Zinc manganese oxide(ZMO)system represents a notable family of mixed transition metal oxides(MTMOs)because of their superiority of the high theoretical capacity,adequacy of natural content,and low cost.However,the methods to match both the reliable synthesis and the designable construction of large-sized two-dimensional(2D)ZMO nanosheets are still considered as grand challenges.Herein,we have successfully realized the preparation of 2D ZMO nanosheets with large lateral sizes up to~20 mm by simple pyrolysis of 2D metal–organic framework(MOF)nanosheets precursor.The growth mechanism of 2D MOF is proposed to be based on the lamellar micelles formed by polyvinyl pyrrolidone(PVP).The obtained 2D and porous ZMO nanosheets exhibit high specific capacity as well as good rate capability.More importantly,the as-prepared ZMO electrode shows a remarkable capacity increment upon cycling(from 832 mAh g^(-1) at the 2nd cycle to 1418 mAh g^(-1) at the 700th cycle,at 1 A g^(-1)).Through simple adjustment of the calcination temperature,the valence state of Mn species in the yielding ZMO samples can be fine-tuned.Through systematic investigation towards these ZMOs containing different Mn species,the extra specific capacity is revealed to be chiefly on account of the arising of the valence state of Mn upon the cycling process.Moreover,it is disclosed that the higher-valent Mn the pristine ZMO contains,the more additional capacity it gains upon cycling.We believe that this work will inspire more detailed analysis on the relationship between the valence state of Mn and extra capacity.

Removing microplastics from aquatic environments:A critical review

As one of the typical emerging contaminants,microplastics exist widely in the environment because of their small size and recalcitrance,which has caused various ecological problems.This paper summarizes current adsorption and removal technologies of microplastics in typical aquatic environments,including natural freshwater,marine,drinking water treatment plants(DWTPs),and wastewater treatment plants(WWTPs),and includes abiotic and biotic degradation technologies as one of the removal technologies.Recently,numerous studies have shown that enrichment technologies have been widely used to remove microplastics in natural freshwater environments,DWTPs,and WWTPs.Efficient removal of microplastics via WWTPs is critical to reduce the release to the natural environment as a key connection point to prevent the transfer of microplastics from society to natural water systems.Photocatalytic technology has outstanding pre-degradation effects on microplastics,and the isolated microbial strains or enriched communities can degrade up to 50%or more of pre-processed microplastics.Thus,more research focusing on microplastic degradation could be carried out by combining physical and chemical pretreatment with subsequent microbial biodegradation.In addition,the current recovery technologies of microplastics are introduced in this review.This is incredibly challenging because of the small size and dispersibility of microplastics,and the related technologies still need further development.This paper will provide theoretical support and advice for preventing and controlling the ecological risks mediated by microplastics in the aquatic environment and share recommendations for future research on the removal and recovery of microplastics in various aquatic environments,including natural aquatic environments,DWTPs,and WWTPs.

One-step synthesis of recoverable CuCo2S4 anode material for high-performance Li-ion batteries

A facile one-step hydrothermal method has been adopted to directly synthesize the CuCo2S4 material on the surface of Ni foam.Due to the relatively large specific surface area and wide pore size distribution,the CuCo2S4 material not only effectively increases the reactive area,but also accommodates more side reaction products to avoid the difficulty of mass transfer.When evaluated as anode for Li-ion batteries,the CuCo2S4 material exhibits excellent electrochemical performance including high discharge capacity,outstanding cyclic stability and good rate performance.At the current density of 200 mA·g^-1,the CuCo2S4 material shows an extremely high initial discharge capacity of 2510 mAh·g^-1,and the cycle numbers of the material even reach 83 times when the discharge capacity is reduced to 500 mAh·g^-1.Furthermore,the discharge capacity can reach 269 mAh·g^-1 at a current of 2000 mA·g^-1.More importantly,when the current density comes back to 200 mA·g^-1,the discharge capacity could be recovered to 1436 mAh·g^-1,suggesting an excellent capacity recovery characteristics.

Enhanced cobalamin biosynthesis in Ensifer adhaerens by regulation of key genes with gradient promoters

Cobalamin is an essential human vitamin widely used in the pharmaceutical,food,and feed additive industries and currently produced by bacteria or archaea.Ensifer adhaerens HY-1 is an industrial strain that also produces cobalamin.However production outputs are poor and the specific synthesis pathways require characterization.In this study,the whole genome sequence of E.adhaerens HY-1 was generated and annotated,and genes associated with cobalamin biosynthesis were identified.Then,three genes,CobSV,CobQ,and CobW were identified as the most efficient ones for enhancing cobalamin synthesis.By transcriptome sequencing of E.adhaerens HY-1 cells at different growth stages,65 endogenous promoters with different gradient strengths were identified.After combined expression of different strength promoters and key genes,a high cobalamin-producing recombinant strain,‘hmm’(genotype:PmetH-CobSV-PibpA-CobQ-Pmdh-CobW),was generated.Cobalamin production was 143.8 mg/L in shaking flasks,which was 41.0%higher than the original strain.Cobalamin production was further enhanced to 171.2 mg/L using fed-batch fermentation.Importantly,our data and novel approach provide important references for the analysis of cobalamin synthesis and other metabolites in complex metabolic pathways.