Single-atom nanozymes (SAzymes), as novel nanozymes with atomically dispersed active sites, are of great importance in the development of nanozymes for their high catalytic activities, the maximum utilization efficiency of metal atoms, and the simple model of active sites. Herein, the peroxidase-like SAzymes with high-concentration Cu sites on carbon nanosheets (Cu–N–C) were synthesized through a salt-template strategy. With the densely distributed active Cu atoms (∼5.1 wt %), the Cu–N–C SAzymes exhibit remarkable activity to mimic natural peroxidase. Integrating Cu–N–C SAzymes with natural acetylcholinesterase and choline oxidase, three-enzyme-based cascade reaction system was constructed for the colorimetric detection of acetylcholine and organophosphorus pesticides. This work not only provides a strategy to synthesize SAzymes with abundant active sites but also gives some new insights for robust nanozyme biosensing systems.

Conversion reaction enables Li/garnet interface to construct a kinetically stable interfacial layer for the homogeneous ions transport in all-solid-batteries.

Oxygen release and irreversible cation migration are the main causes of voltage fade in Li-rich transition metal oxide cathode. But their correlation is not very clear and voltage decay is still a bottleneck. Herein, we modulate the oxygen anionic redox chemistry by constructing Li2ZrO3 slabs into Li2MnO3 domain in Li1.21Ni0.28Mn0.51O2, which induces the lattice strain, tunes the chemical environment for redox-active oxygen and enlarges the gap between metallic and anionic bands. This modulation expands the region in which lattice oxygen contributes capacity by oxidation to oxygen holes and relieves the charge transfer from anionic band to antibonding metal–oxygen band under a deep delithiation. This restrains cation reduction, metal–oxygen bond fracture, and the formation of localized O2 molecule, which fundamentally inhibits lattice oxygen escape and cation migration. The modulated cathode demonstrates a low voltage decay rate (0.45 millivolt per cycle) and a long cyclic stability.

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We present a facile route towards a dual single-atom nanozyme composed of Zn and Mo, which utilizes the non-covalent nano-assembly of polyoxometalates, supramolecular coordination complexes as the metal-atom precursor, and a macroscopic amphiphilic aerogel as the supporting substrate. The dual singleatoms of Zn and Mo have a high content (1.5 and 7.3 wt %, respectively) and exhibit a synergistic effect and a peroxidase-like activity. The Zn/Mo site was identified as the main active center by X-ray absorption fine structure spectroscopy and density functional theory calculation. The detection of versatile analytes, including intracellular H 2 O 2 , glucose in serum, cholesterol, and ascorbic acid in commercial beverages was achieved. The nanozyme has an outstanding stability and maintained its performance after one year's storage. This study develops a new peroxidase-like nanozyme and provides a robust synthetic strategy for single-atom catalysts by utilizing an aerogel as a facile substrate that is capable of stabilizing various metal atoms.

All-solid-state lithium-ion battery is considered to be one of the most promising next-generation battery technologies. Understanding the interfacial evolution of a solid electrolyte and a cathode electrode during mixing and sintering is of great importance and can provide guidance to avoid forming unwanted compounds and decrease the interfacial resistance. In this work, chemical compatibilities are investigated between a Ta-doped Li 7 La 3 Zr 2 O 12 (LLZO) solid electrolyte and major commercial metal-oxide cathodes LiCoO 2 (LCO) and Li(NiCoMn) 1/3 O 2 (NCM) through ballmilling and cosintering processes. As revealed by X-ray absorption spectroscopy and transmission electron microscopy, LLZO spontaneously covers the majority of the large LCO and NCM particles with a thickness of ∼100 nm after ball milling. The thickness of LLZO layer on these cathodes decreases to about 10 nm after cosintering at 873 K, and an interfacial layer of approximately 3 nm is observed for NCM/LLZO. LCO shows a higher thermal stability than NCM. Density functional theory (DFT)-based simulations and electrochemical measurements suggest Ni−La and Ni−Li exchange could happen at the NCM/LLZO interface and Li can diffuse from the interface into NCM to occupy the Ni vacancy at high temperature. The Li depletion layer after diffusion at the interface induces the decomposition of LLZO and the formation of La 2 Zr 2 O 7 and LaNiO 3 interfacial layer.

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The use of anion redox reactions is gaining interest for increasing rechargeable capacities in alkaline ion batteries. Although anion redox coupling of S2− and (S2)2− through dimerization of S–S in sulfides have been studied and reported, an anion redox process through electron hole formation has not been investigated to the best of our knowledge. Here, we report an O3-NaCr2/3Ti1/3S2 cathode that delivers a high reversible capacity of ~186 mAh g−1 (0.95 Na) based on the cation and anion redox process. Various charge compensation mechanisms of the sulfur anionic redox process in layered NaCr2/3Ti1/3S2, which occur through the formation of disulfide-like species, the precipitation of elemental sulfur, S–S dimerization, and especially through the formation of electron holes, are investigated. Direct structural evidence for formation of electron holes and (S2)n− species with shortened S–S distances is obtained. These results provide valuable information for the development of materials based on the anionic redox reaction.