Search

Calcium ion batteries (CIBs) are considered as an important candidate for post‐lithium energy storage devices due to their abundance of resources and low cost. However, CIBs still suffer from slow kinetics due to the large solvation structure and high desolvation energy of Ca2+ ions. Here, a solvation regulation strategy based on donor number (DN) is reported to achieve easy‐desolvation and rapid storage of Ca2+ in sodium vanadate (Na2V6O16·2H2O, NVO). Specially, the solvent with a low DN, represented by propylene carbonate (PC), forms the first solvation shell of calcium ions with weak binding energy and small shell structure, which facilitates the migration of Ca2+ in the electrolyte. More importantly, the low DN solvent is preferentially desolvated at the cathode/electrolyte interface, promoting the insertion of Ca2+ into the NVO electrode. Mechanism studies further confirm the highly reversible uptake/release of Ca2+ in the NVO cathode, along with the VO distance change in the coordination structure. Therefore, the NVO cathode achieves high capacity (376 mAh g−1 at 0.3 A g−1) and high‐rate performance (151 mAh g−1 at 5 A g−1). The weak solvation effect strategy further improves the electrochemical performance and provides great importance for the design of the long‐term development of CIBs. [ABSTRACT FROM AUTHOR]

Compensating the irreversible loss of limited active lithium (Li) is essentially important for improving the energy‐density and cycle‐life of practical Li‐ion battery full‐cell, especially after employing high‐capacity but low initial coulombic efficiency anode candidates. Introducing prelithiation agent can provide additional Li source for such compensation. Herein, we precisely implant trace Co (extracted from transition metal oxide) into the Li site of Li2O, obtaining (Li0.66Co0.11□0.23)2O (CLO) cathode prelithiation agent. The synergistic formation of Li vacancies and Co‐derived catalysis efficiently enhance the inherent conductivity and weaken the Li−O interaction of Li2O, which facilitates its anionic oxidation to peroxo/superoxo species and gaseous O2, achieving 1642.7 mAh/g~Li2O prelithiation capacity (≈980 mAh/g for prelithiation agent). Coupled 6.5 wt % CLO‐based prelithiation agent with LiCoO2 cathode, substantial additional Li source stored within CLO is efficiently released to compensate the Li consumption on the SiO/C anode, achieving 270 Wh/kg pouch‐type full‐cell with 92 % capacity retention after 1000 cycles. [ABSTRACT FROM AUTHOR]

Vanadate materials are feasible cathodes for metal–ion batteries due to their stable layered structure, abundant valence states, and high capacity. However, much uncertainty still exists about precisely modulating intercalants to facilitate ion storage. Here, V2O5 pre‐intercalated with various transition metal ions M2+ (M═Ni, Co, Mn) are developed as model materials to analyze the coupling effect between guest ions and host material. Through density functional theory simulations, it is found that M2+ interacts with V–O chain via M 3d‐O 2p covalent bonds, and extended X‐ray absorption fine structure reveals the Ni─O interatomic distance at 1.56 Å shorter than Co─O (1.60 Å) and Mn─O (1.72 Å), suggesting the M–O band type with different covalency degree can optimize VOx polyhedron and local electronic structure. Furthermore, NiVO cathode materials with the smallest layer spacing shows higher redox voltage and better rate/cycling performance for Ca2+ storage than CoVO/MnVO, elucidating that Ni has stronger tendency to attract electrons and bonds with V–O layer tightly, thus supplying a reliable ion diffusion channel for Ca2+. Through ions pre‐intercalated techniques, this work highlights both layer spacing and physicochemical properties of intercalants affect electrochemical process, which is significant for developing high‐performance vanadate cathode materials. [ABSTRACT FROM AUTHOR]

Coupling the structure advantages of platinum (Pt)-based active composites, transition-metal single sites, and porous carbon is highly desirable to reduce the Pt usage in proton-exchange membrane fuel cells (PEMFCs) but remains a great challenge. Herein, we report the in situ construction of synergistic oxygen reduction reaction (ORR) catalysts with intermetallic PtZn alloy nanoparticles confined in mesoporous carbon doped with atomic Co–N4 and Zn–N4 moieties. Mesoporous carbon doped with Co–N4 and Zn–N4 moieties could be fabricated by carbonization of CoSO4-doped ZIF-8 precursors and SO42– has been verified to be responsible for the formation of mesopores and defects with narrow pore size distribution. More importantly, systematical characterizations revealed that Pt could in situ alloy with Zn–N4 sites, which could effectively prevent the agglomeration of Pt during high-temperature treatment, leading to the formation of uniform and well-dispersed PtZn nanoparticles with a mean diameter of ∼3.06 nm. The as-synthesized PtZn@Meso/Zn1Co1/NC shows an excellent mass activity of 490 mA mgPt–1 @ 0.9 V as well as excellent durability with an activity retention of 79% after 20,000 potential cycles in 0.1 M HClO4, showing that the nanoarchitecture of the mesopore-encased PtZn alloy has a high resistance to migration due to the pore confinement effect and anchoring effect of the support. In addition to developing robust Pt-based catalysts, this study also lays out a straightforward strategy for designing synergistic catalysts, which might have far-reaching implications for fuel cells and beyond. [ABSTRACT FROM AUTHOR]

Electrocatalytic acetylene semi-hydrogenation to ethylene powered by renewable electricity represents a sustainable pathway, but the inadequate current density and single-pass yield greatly impedes the production efficiency and industrial application. Herein, we develop a F-modified Cu catalyst that shows an industrial partial current density up to 0.76 A cm−2 with an ethylene Faradic efficiency surpass 90%, and the maximum single-pass yield reaches a notable 78.5%. Furthermore, the Cu-F showcase the capability to directly convert acetylene into polymer-grade ethylene in a tandem flow cell, almost no acetylene residual in the production. Combined characterizations and calculations reveal that the Cuδ+ (near fluorine) enhances the water dissociation, and the generated active hydrogen are immediately transferred to Cu0 (away from fluorine) and react with the locally adsorbed acetylene. Therefore, the hydrogen evolution reaction is surpassed and the overall acetylene semi-hydrogenation performance is boosted. Our findings provide new opportunity towards rational design of catalysts for large-scale electrosynthesis of ethylene and other important industrial raw. Efficient electroreduction of acetylene to ethylene is crucial for industrial applications. Here, the authors reported fluorine modified copper for direct conversion of acetylene to polymer-grade ethylene in one single-pass with industrial-current-density. [ABSTRACT FROM AUTHOR]

Exploring efficient transition-metal-based electrocatalysts for oxygen evolution reaction (OER) is imperative but remain challenging for sustainable energy storage and conversion systems. Foreign species doping is a significant regulation strategy to enhance the intrinsic activity of host matrix. However, the potential relationship of structure-activity caused by guest doping elements is seldom tracked systematically. In this case, both theoretical screening and experimental verification are complementarily employed to investigate the guest doping effects of ten first-row transition metals (Sc~Zn) on bimetallic NiCo layered double hydroxide (NiCo-LDH). As a result, the optimized Fe-doped NiCo-LDH is identified as the most promising candidate toward alkaline electrocatalytic OER, which exhibits the quasi-industrial current density of 1000 mA cm-2 at overpotential of400 mV. Meanwhile, it also shows impressively long-term stability of 500 h at 500 mA cm-2 with a negligible activity loss. Moreover, in situ electrochemical Raman spectroscopy unveils the dynamic structure evolution from pre-catalytic state (Fe-NiCo-LDH) to metal oxyhydroxide (Fe-(NiCo)OOH) during the oxidation reaction, and ab-initio molecular dynamics simulations are further performed to confirm the thermodynamic stability of activated Fe-(NiCo)OOH phase. This work provides a promising platform for exploring the critical role of transition metal guest doping on host matrix in developing industrially required OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Recently, nanozyme-based sensing platforms have attracted widespread attention due to their excellent performance in practical applications. In this paper, phosphorus-doped porous materials were synthesized by a one-step method and metal-doped with different metal salts. The results show that the iron-containing porous nitrogen-phosphorus material (FeNPC) has the best peroxidase activity. FeNPC catalyzes hydrogen peroxide to generate hydroxyl radical (•OH) which oxidizes colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxTMB. When the above system encounters ferulic acid, the blue product will be inhibited, and the color of the reaction solution will change, so ferulic acid can be detected by the colorimetric method. Ferulic acid is an antioxidant used in humans as an antibacterial and antiviral drug. The detection limit of this colorimetric sensor is as low as 1.3 nM. Compared with other detection methods, the colorimetric method is simple, fast, and cheap and has a good development prospect. [ABSTRACT FROM AUTHOR]