Oxygen‐Deficient Blue TiO2 for Ultrastable and Fast Lithium Storage

Developing a titanium dioxide (TiO₂)‐based anode with superior high‐rate capability and long‐term cycling stability is important for efficient energy storage. Herein, a simple one‐step approach for fabricating blue TiO₂ nanoparticles with oxygen vacancies is reported. Oxygen vacancies can enlarge lattice spaces, lower charge transfer resistance, and provide more active sites in TiO₂ lattices. As a result, this blue TiO₂ electrode exhibits a highly reversible capacity of 50 mAh g^?1 at 100 C (16 800 mA g^?1) even after 10 000 cycles, which is attributable to the combination of surface capacitive process and remarkable diffusion‐controlled insertion revealed by the kinetic analysis. The strategy of employing oxygen‐deficient nanoparticles may be extended to the design of other robust semiconductor materials as electrodes for energy storage.     

Boosting Superior Lithium Storage Performance of Alloy‐Based Anode Materials via Ultraconformal Sb Coating–Derived Favorable Solid‐Electrolyte Interphase

Alloy materials such as Si and Ge are attractive as high‐capacity anodes for rechargeable batteries, but such anodes undergo severe capacity degradation during discharge–charge processes. Compared to the over‐emphasized efforts on the electrode structure design to mitigate the volume changes, understanding and engineering of the solid‐electrolyte interphase (SEI) are significantly lacking. This work demonstrates that modifying the surface of alloy‐based anode materials by building an ultraconformal layer of Sb can significantly enhance their structural and interfacial stability during cycling. Combined experimental and theoretical studies consistently reveal that the ultraconformal Sb layer is dynamically converted to Li₃Sb during cycling, which can selectively adsorb and catalytically decompose electrolyte additives to form a robust, thin, and dense LiF‐dominated SEI, and simultaneously restrain the decomposition of electrolyte solvents. Hence, the Sb‐coated porous Ge electrode delivers much higher initial Coulombic efficiency of 85% and higher reversible capacity of 1046 mAh g^?1 after 200 cycles at 500 mA g^?1, compared to only 72% and 170 mAh g^?1 for bare porous Ge. The present finding has indicated that tailoring surface structures of electrode materials is an appealing approach to construct a robust SEI and achieve long‐term cycling stability for alloy‐based anode materials.     

In Situ Electrochemical Synthesis of MXenes without Acid/Alkali Usage in/for an Aqueous Zinc Ion Battery

The traditional method to fabricate a MXene based energy storage device starts from etching MAX phase particles with dangerous acid/alkali etchants to MXenes, followed by device assembly. This is a multistep protocol and is not environmentally friendly. Herein, an all‐in‐one protocol is proposed to integrate synthesis and battery fabrication of MXene. By choosing a special F‐rich electrolyte, MAX V₂AlC is directly exfoliated inside a battery and the obtained V₂CT_X MXene is in situ used to achieve an excellent battery performance. This is a one‐step process with all reactions inside the cell, avoiding any contamination to external environments. Through the lifetime, the device experiences three stages of exfoliation, electrode oxidation, and redox of V₂O₅. While the electrode is changing, the device can always be used as a battery and the performance is continuously enhanced. The resulting aqueous zinc ion battery achieves outstanding cycling stability (4000 cycles) and rate performance (97.5 mAh g^?1 at 64 A g^?1), distinct from all reported aqueous MXene‐based counterparts with pseudo‐capacitive properties, and outperforming most vanadium‐based zinc ion batteries with high capacity. This work sheds light on the green synthesis of MXenes, provides an all‐in‐one protocol for MXene devices, and extends MXenes’ application in the aqueous energy storage field.     

Optimized Catalytic WS2–WO3 Heterostructure Design for Accelerated Polysulfide Conversion in Lithium–Sulfur Batteries

The lithium–sulfur (Li–S) battery is a next generation high energy density battery, but its practical application is hindered by the poor cycling stability derived from the severe shuttling of lithium polysulfides (LiPSs). Catalysis is a promising way to solve this problem, but the rational design of relevant catalysts is still hard to achieve. This paper reports the WS₂–WO₃ heterostructures prepared by in situ sulfurization of WO₃, and by controlling the sulfurization degree, the structure is controlled, which balances the trapping ability (by WO₃) and catalytic activity (by WS₂) toward LiPSs. As a result, the WS₂–WO₃ heterostructures effectively accelerate LiPS conversion and improve sulfur utilization. The Li–S battery with 5 wt% WS₂–WO₃ heterostructures as additives in the cathode shows an excellent rate performance and good cycling stability, revealing a 0.06% capacity decay each cycle over 500 cycles at 0.5 C. By building an interlayer with such heterostructure‐added graphenes, the battery with a high sulfur loading of 5 mg cm^?2 still shows a high capacity retention of 86.1% after 300 cycles at 0.5 C. This work provides a rational way to prepare the metal oxide–sulfide heterostructures with an optimized structure to enhance the performance of Li–S batteries.     

Double the Capacity of Manganese Spinel for Lithium‐Ion Storage by Suppression of Cooperative Jahn–Teller Distortion

The relatively low capacity and capacity fade of spinel LiMn₂O₄ (LMO) limit its application as a cathode material for lithium‐ion batteries. Extending the potential window of LMO below 3 V to access double capacity would be fantastic but hard to be realized, as it will lead to fast capacity loss due to the serious Jahn–Teller distortion. Here using experiments combined with extensive ab initio calculations, it is proved that there is a cooperative effect among individual Jahn–Teller distortions of Mn³⁺O₆ octahedrons in LMO, named as cooperative Jahn–Teller distortion (CJTD) in the text, which is the difficulty to access the capacity beyond one lithium intercalation. It is further proposed that the cationic disordering (excess Li at Mn sites and Li/Mn exchange) can intrinsically suppress the CJTD of Mn³⁺O₆ octahedrons. The cationic disordering can break the symmetry of Mn³⁺ arrangements to disrupt the correlation of distortions arising from individual JT centers and prevent the Mn³⁺? O bonds distorting along one direction. Interestingly, with the suppressed CJTD, the original octahedral vacancies in spinel LMO are activated and can serve as extra Li‐ion storage sites to access the double capacity with good reversible cycling stability in microsized LMO.     

Accelerating Atomic Catalyst Discovery by Theoretical Calculations‐Machine Learning Strategy

Atomic catalysts (AC) are emerging as a highly attractive research topic, especially in sustainable energy fields. Lack of a full picture of the hydrogen evolution reaction (HER) impedes the future development of potential electrocatalysts. In this work, the systematic investigation of the HER process in graphdyine (GDY) based AC is presented in terms of the adsorption energies, adsorption trend, electronic structures, reaction pathway, and active sites. This comprehensive work innovatively reveals GDY based AC for HER covering all the transition metals (TM) and lanthanide (Ln) metals, enabling the screening of potential catalysts. The density functional theory (DFT) calculations carefully explore the HER performance beyond the comparison of sole H adsorption. Therefore, the screened catalysts candidates not only match with experimental results but also provide significant references for novel catalysts. Moreover, the machine learning (ML) technique bag‐tree approach is innovatively utilized based on the fuzzy model for data separation and converse prediction of the HER performance, which indicates a similar result to the theoretical calculations. From two independent theoretical perspectives (DFT and ML), this work proposes pivotal guidelines for experimental catalyst design and synthesis. The proposed advanced research strategy shows great potential as a general approach in other energy‐related areas.     

Simultaneous nitrogen and carbon removal in a packed A/O reactor: effect of C/N ratio on microbial community structure

In this research, a novel packed anoxic/oxic moving bed biofilm reactor (MBBR) was established to achieve high-organic matter removal rates, despite the carbon/nitrogen (C/N) ratio of 2.7–5.1 in the influent. Simultaneous nitrification–denitrification (SND) was investigated under a long sludge retention time of 104 days. The system exhibited excellent performance in pollutant removal, with chemical oxygen demand and total nitrogen (TN) enhanced to 93.6–97.4% and 34.4–60%, respectively. Under low C/N conditions, the nitrogen removal process of A/O MBBR system was mainly achieved by anaerobic denitrification. The increase of C/N ratio enhanced SND rate of the aerobic section, where dissolved oxygen was maintained at the range of 4–6 mg/L, and resulted in higher TN removal efficiency. The microbial composition and structures were analyzed utilizing the MiSeq Illumina sequencing technique. High-throughput pyrosequencing results indicated that the dominant microorganisms were Proteobacteria and Bacteroidetes at the phylum level, which contributes to the removal of organics matters. In the aerobic section, abundances of Nitrospirae (1.12–29.33%), Burkholderiales (2.15–21.38%), and Sphingobacteriales (2.92–11.67%) rose with increasing C/N ratio in the influent, this proved that SND did occur in the aerobic zone. As the C/N ratio of influent increased, the SND phenomenon in the aerobic zone of the system is the main mechanism for greatly improving the removal rate of TN in the aerobic section. The C/N ratio in the aerobic zone is not required to be high to exhibit good TN removal performance. When C/NH₄⁺ and C/TN in the aerobic zone were higher than 2.29 and 1.77, respectively, TN removal efficiency was higher than 60%, which means that carbon sources added to the reactor could be saved. This study would be vital for a better understanding of microbial structures within a packed A/O MBBR and the development of cost-efficient strategies for the treatment of low C/N wastewater.

     

Human Monoclonal Antibodies: On the Menu of Targeted Therapeutics Against COVID-19

Virologica Sinica - Coronavirus disease 2019 (COVID-19), reminiscent of the severe acute respiratory syndrome (SARS) outbreak in 2003, has been a tragic disaster to people all over the world. As...