Large‐Area Synthesis of Superclean Graphene via Selective Etching of Amorphous Carbon with Carbon Dioxide

Contamination commonly observed on the graphene surface is detrimental to its excellent properties and strongly hinders its application. It is still a great challenge to produce large‐area clean graphene film in a low‐cost manner. Herein, we demonstrate a facile and scalable chemical vapor deposition approach to synthesize meter‐sized samples of superclean graphene with an average cleanness of 99 %, relying on the weak oxidizing ability of CO₂ to etch away the intrinsic contamination, i.e., amorphous carbon. Remarkably, the elimination of amorphous carbon enables a significant reduction of polymer residues in the transfer of graphene films and the fabrication of graphene‐based devices and promises strongly enhanced electrical and optical properties of graphene. The facile synthesis of large‐area superclean graphene would open the pathway for both fundamental research and industrial applications of graphene, where a clean surface is highly needed.     

Elucidating Molecule–Plasmon Interactions in Nanocavities with 2 nm Spatial Resolution and at the Single‐Molecule Level

The fundamental understanding of the subtle interactions between molecules and plasmons is of great significance for the development of plasmon‐enhanced spectroscopy (PES) techniques with ultrahigh sensitivity. However, this information has been elusive due to the complex mechanisms and difficulty in reliably constructing and precisely controlling interactions in well‐defined plasmonic systems. Herein, the interactions in plasmonic nanocavities of film‐coupled metallic nanocubes (NCs) are investigated. Through engineering the spacer layer, molecule–plasmon interactions were precisely controlled and resolved within 2 nm. Efficient energy exchange interactions between the NCs and the surface within the 1–2 nm range are demonstrated. Additionally, optical dressed molecular excited states with a huge Lamb shift of ≈7 meV at the single‐molecule (SM) level were observed. This work provides a basis for understanding the underlying molecule–plasmon interaction, paving the way for fully manipulating light–matter interactions at the nanoscale.     

Direct Visualization of Live Zebrafish Glycans via Single‐Step Metabolic Labeling with Fluorophore‐Tagged Nucleotide Sugars

Dynamic turnover of cell‐surface glycans is involved in a myriad of biological events, making this process an attractive target for in vivo molecular imaging. Metabolic glycan labeling coupled with bioorthogonal chemistry has paved the way for visualizing glycans in living organisms. However, a two‐step labeling sequence is required, which suffers from the tissue‐penetration difficulties of the imaging probes. Here, by exploring the substrate promiscuity of endogenous glycosyltransferases, we developed a single‐step fluorescent glycan labeling strategy by using fluorophore‐tagged analogues of the nucleotide sugars. Injecting fluorophore‐tagged sialic acid and fucose into the yolk of zebrafish embryos at the one‐cell stage enables systematic imaging of sialylation and fucosylation in live zebrafish embryos at distinct developmental stages. From these studies, we obtained insights into the role of sialylated and fucosylated glycans in zebrafish hematopoiesis.     

Boosting Hydrogen Oxidation Activity of Ni in Alkaline Media through Oxygen‐Vacancy‐Rich CeO2/Ni Heterostructures

The search for highly efficient platinum group metal (PGM)‐free electrocatalysts for the hydrogen oxidation reaction (HOR) in alkaline electrolytes remains a great challenge in the development of alkaline exchange membrane fuel cells (AEMFCs). Here we report the synthesis of an oxygen‐vacancy‐rich CeO₂/Ni heterostructure and its remarkable HOR performance in alkaline media. Experimental results and density functional theory (DFT) calculations indicate the electron transfer between CeO₂ and Ni could lead to thermoneutral adsorption free energies of H* (ΔG_H*). This, together with the promoted OH* adsorption strength derived from the abundance of oxygen vacancies in the CeO₂ species, contributes to the excellent HOR performance with the exchange current density and mass activity of 0.038 mA cm_Ni^?2 and 12.28 mA mg_Ni^?1, respectively. This presents a new benchmark for PGM‐free alkaline HOR and opens a new avenue toward the rational design of high‐performance PGM‐free electrocatalysts for alkaline HOR.     

Dual Graphitic‐N Doping in a Six‐Membered C‐Ring of Graphene‐Analogous Particles Enables an Efficient Electrocatalyst for the Hydrogen Evolution Reaction

Graphene‐based materials still exhibit poor electrocatalytic activities for the hydrogen evolution reaction (HER) although they are considered to be the most promising electrocatalysts. We fabricated a graphene‐analogous material displaying exceptional activity towards the HER under acidic conditions with an overpotential (57 mV at 10 mA cm^?2) and Tafel slope (44.6 mV dec^?1) superior to previously reported graphene‐based materials, and even comparable to the state‐of‐the art Pt/C catalyst. X‐ray absorption near‐edge structure (XANES) and solid‐state NMR studies reveal that the distinct feature of its structure is dual graphitic‐N doping in a six‐membered carbon ring. Density functional theory (DFT) calculations show that the unique doped structure is beneficial for the activation of C?H bonds and to make the carbon atom bonded to two graphitic N atoms an active site for the HER.     

Ultrafast Removal of Cadmium(II) by Green Cyclodextrin Metal–Organic‐Framework‐Based Nanoporous Carbon: Adsorption Mechanism and Application

Water contaminated with heavy metals has been identified as a significant threat to human health. Therefore, the development of safe and rapid water‐treatment techniques is necessary. We have synthesized an eco‐friendly γ‐cyclodextrin metal–organic framework (MOF)‐based nanoporous carbon (γ‐CD MOF‐NPC) material, conducted a comprehensive characterization of it, and found its rapid and effective Cd^II‐removal capacity. The γ‐CD MOF‐NPC could effectively sequester a majority of cadmium ions within one minute, and it still demonstrated excellent adsorption ability under various conditions, including different pH, adsorbent dosage, and coexistent ions. The maximum adsorption capacity was calculated to be 140.85 mg g^?1 by means of the Langmuir model. The adsorption was primarily due to the effect of ion exchange of oxygen‐containing functional groups, as determined by studying the ζ potential and Fourier transform infrared spectroscopy. Flow‐through experiments further proved the rapid Cd^II‐removal capacity and potential of the practical application of γ‐CD MOF‐NPC in water treatment according to the cytotoxic data.     

A Reversible Liquid Organic Hydrogen Carrier System Based on Methanol‐Ethylenediamine and Ethylene Urea

A novel liquid organic hydrogen carrier (LOHC) system, with a high theoretical hydrogen capacity, based on the unpresented hydrogenation of ethylene urea to ethylenediamine and methanol, and its reverse dehydrogenative coupling, was established. For the dehydrogenation only a small amount of solvent is required. This system is rechargeable, as the H₂‐rich compounds could be regenerated by hydrogenation of the resulting dehydrogenation mixture. Both directions for hydrogen loading and unloading were achieved using the same catalyst, under relatively mild conditions. Mechanistic studies reveal the likely pathway for H₂‐lean compounds formation.     

Ultra‐Tough Inverse Artificial Nacre Based on Epoxy‐Graphene by Freeze‐Casting

Epoxy nanocomposites combining high toughness with advantageous functional properties are needed in many fields. However, fabricating high‐performance homogeneous epoxy nanocomposites with traditional methods remains a great challenge. Nacre with outstanding fracture toughness presents an ideal blueprint for the development of future epoxy nanocomposites. Now, high‐performance epoxy‐graphene layered nanocomposites were demonstrated with ultrahigh toughness and temperature‐sensing properties. These nanocomposites are composed of ca. 99 wt % organic epoxy, which is in contrast to the composition of natural nacre (ca. 96 wt % inorganic aragonite). These nanocomposites are named an inverse artificial nacre. The fracture toughness reaches about 4.2 times higher than that of pure epoxy. The electrical resistance is temperature‐sensitive and stable under various humidity conditions. This strategy opens an avenue for fabricating high‐performance epoxy nanocomposites with functional properties.