In this work we demonstrate a facile means to generate fluorescent carbon nanoribbons, nanoparticles, and graphene from graphite electrode using ionic liquid-assisted electrochemical exfoliation. A time-dependence study of products exfoliated from the graphite anode allows the reconstruction of the exfoliation mechanism based on the interplay of anodic oxidation and anion intercalation. We have developed strategies to control the distribution of the exfoliated products. In addition, the fluorescence of these carbon nanomaterials can be tuned from the visible to ultraviolet region by controlling the water content in the ionic liquid electrolyte.

Electrochemical conversion of CO2 into valued products is one of the most important issues but remains a great challenge in chemistry. Herein, we report a novel synthetic approach involving prolonged thermal pyrolysis of hemin and melamine molecules on graphene for the fabrication of a robust and efficient single‐iron‐atom electrocatalyst for electrochemical CO2 reduction. The single‐atom catalyst exhibits high Faradaic efficiency (ca. 97.0 %) for CO production at a low overpotential of 0.35 V, outperforming all Fe‐N‐C‐based catalysts. The remarkable performance for CO2‐to‐CO conversion can be attributed to the presence of highly efficient singly dispersed FeN5 active sites supported on N‐doped graphene with an additional axial ligand coordinated to FeN4. DFT calculations revealed that the axial pyrrolic nitrogen ligand of the FeN5 site further depletes the electron density of Fe 3d orbitals and thus reduces the Fe–CO π back‐donation, thus enabling the rapid desorption of CO and high selectivity for CO production.

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A method, by which periodic two-dimensional arrays of identical metal clusters of nanometer size and spacing could be spontaneously obtained by taking advantage of surface mediated clustering, is reported. The versatility of the method is demonstrated for a broad range of metals on Si(111)-(7 x 7) substrates. In situ scanning tunneling microscopy analysis of In clusters, combined with first-principles total energy calculations, unveils unique initial-stage atomic structures of the surface-supported clusters and the vital steps that lead to the success of this method. A strong interaction between the clusters and the surface holds the key to the observed cluster sizes.

A high-rate graphene-based supercapacitor is very attractive for the practical application of graphene. Here, we first synthesized the films of the hybrids of biomass cellulose and large literal sheet sizes and weakly defective graphene flakes reaching high thermal conductivity and then converted them into hierarchical porous graphene carbon materials reaching superior supercapacity. The interconnected porous carbon framework, with macroporous walls sandwiched by micro/mesoporous activated carbon covering graphene flakes, was synthesized by template-free low-temperature activation of the cellulose/graphene hybrids at 650°C. The graphene flakes could probably assist both the decrease in the temperature of the chemical activation of cellulose and the formation of the hierarchical carbon pores without destroying their sp 2 bonds. The porous graphene carbon-based supercapacitors exhibit a reversible specific capacitance of ∼300 F/g and ultrahigh energy storage performance of 67 Wh/kg, 54 Wh/L, and 60 kW/kg over a 45 s discharge time. ■ INTRODUCTIONHigh-energy density storage and fast response supercapacitors are needed to serve the people to keep up with the high pace of modern life. 1−6 A hierarchical porous carbon framework with micro-, meso-, and macropores can be made into desirable electrodes for high-performance supercapacitors. 7−10 The macropores can work as a fast buffering reservoir for electrolytes, minimizing the diffusion distance of the ions and electrolytes from each pore, while the meso-and micropores provide a large accessible surface area for ion transport and charge accommodation. 11,12 Recently, porous graphene-based composites have received intense attention because the flat open atomic structure of graphene allows ions and electrolytes fast access to its surface with the result being a fast charging or discharging rate for energy storage. 13−17 On the other hand, although the theoretical specific surface area of a single graphene sheet is 2630 m 2 /g, experimentally accessible surface areas of graphene materials are far below this value because of the strong self-aggregation/stacking tendency of graphene flakes (GFs). To prevent the aggregation, many scientists and engineers are trying to design a three-dimensional (3D) framework, including converting flat flexible two-dimensional (2D) into 3D structure or making activated carbon and graphene hybrids. 18−22 Recently, Zhu and his co-workers 23 reported that reduced graphene oxide activated KOH at 800°C to yield a special 3D activated carbon analogue with a large surface area of >3000 m 2 /g as the electrode in a two-electrode symmetrical supercapacitor with excellent electrochemical performance. More recently, graphene oxide and polymer were also activated to produce 3D porous carbon with a large surface area and high specific capacity. 24,25 However, in most cases, (reduced) graphene oxides were used as a starting material, which remains costly and is not competitive with commercial activated carbon. In addition, (reduced) graphene oxides were c...

Artificial nanocluster crystals of In, Ga, and Al were fabricated using a technique in which surface mediated magic clustering is used to achieve identical cluster size while the Si͑111͒-7ϫ7 surface is used as a template for ordering the clusters. The atomic structures, formation mechanism and stability of the nanoclusters were studied with in situ scanning tunneling microscopy combined with first-principles total energy calculations. Our study shows that delicate control of growth kinetics is extremely important for cluster crystal fabrication, and there is essentially no limitation to this method. The high thermal stability and unique structure make these artificial nanocluster crystals promising for various applications.

PD-L1 may contribute to negative regulation of the immune response in chronic hepatitis B. PD-1 and PD-Ls may play a role in immune evasion of tumors.

Strong vibrational coupling has been realized in a variety of mechanical systems. However, there have been no experimental observations of strong coupling of the acoustic modes of plasmonic nanostructures, due to rapid energy dissipation in these systems. Here we realized strong vibrational coupling in ultra-high frequency plasmonic nanoresonators by increasing the vibrational quality factors by an order of magnitude. We achieved the highest frequency quality factor products of f × Q = 1.0 × 10 13 Hz for the fundamental mechanical modes, which exceeds the value of 0.6 × 10 13 Hz required for ground state cooling. Avoided crossing was observed between vibrational modes of two plasmonic nanoresonators with a coupling rate of g = 7.5 ± 1.2 GHz, an order of magnitude larger than the dissipation rates. The intermodal strong coupling was consistent with theoretical calculations using a coupled oscillator model. Our results enabled a platform for future observation and control of the quantum behavior of phonon modes in metallic nanoparticles.