Epitaxial Growth of Main Group Monoelemental 2D Materials

Since the discovery of graphene, 2D materials have attracted significant attention for their unique properties. Monoelemental 2D materials (ME2DMs) are of particular interest because of their superiority in synthetic exploration, excellent mobility, and wide range of band gaps over other 2D compounds. Substantial efforts are devoted to fabricate high-quality materials through various substrates and reveal the growth mechanism at the atomic scale. In this review, the recent progress in the preparation of these ME2DMs is explored, the roles of different substrates is highlighted, and the challenges of and perspectives on their heterostructures is discussed.     

Pyracylene rearrangement classes of fullerene isomers

Isomers of C_n, n ⩽ 70, were generated and classified according to their interconvertibility by the pyracylene rearrangement. The algorithm used for generation of fullerene isomers represents an improvement of the spiral ring algorithm. Class cardinalities and the resonance energies of the most stable representatives are tabulated.     

Recent advances on metal-free graphene-based catalysts for the production of industrial chemicals

With the development of carbon catalysts, graphene-based metal-free catalysts have drawn increasing attention in both scientific research and in industrial chemical production processes. In recent years, the catalytic activities of metal-free catalysts have significantly improved and they have become promising alternatives to traditional metal-based catalysts. The use of metal-free catalysts greatly improves the sustainability of chemical processes. In view of this, the recent progress in the preparation of graphene-based metal-free catalysts along with their applications in catalytic oxidation, reduction and coupling reactions are summarized in this review. The future trends and challenges for the design of graphene-based materials for industrial organic catalytic reactions with good stabilities and high catalytic performance are also discussed.     

Layered double hydroxides with atomic-scale defects for superior electrocatalysis

Atomic composition tuning and defect engineering are effective strategies toenhance the catalytic performance of multicomponent catalysts by improvingthe synergetic effect; however, it remains challenging to dramatically tune the active sites on multicomponent materials through simultaneous defect engineeringat the atomic scale because of the similarities of the local environment. Herein,using the oxygen evolution reaction (OER) as a probe reaction, we deliberatelyintroduced base-soluble Zn(II) or Al(III) sites into NiFe layered double hydroxides(LDHs), which are one of the best OER catalysts. Then, the Zn(II) or Al(III) siteswere selectively etched to create atomic M(II)/M(III) defects, which dramaticallyenhanced the OER activity. At a current density of 20 mA·cm^?2, only 200 mV overpotential was required to generate M(II) defect-rich NiFe LDHs, which is the best NiFe-based OER catalyst reported to date. Density functional theory(DFT) calculations revealed that the creation of dangling Ni–Fe sites (i.e., unsaturated coordinated Ni–Fe sites) by defect engineering of a Ni–O–Fe site at the atomic scale efficiently lowers the Gibbs free energy of the oxygen evolutionprocess. This defect engineering strategy provides new insights into catalysts atthe atomic scale and should be beneficial for the design of a variety of catalysts.

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Polyhedral oligomeric silsesquioxane-coated nanodiamonds for multifunctional applications

Polyhedral oligomeric silsesquioxane (POSS)-coated nanodiamonds (NDs@POSS) were prepared via the amide formation between amine-functionalized POSS and oxygen-containing groups of NDs. The POSS structures grafted on the surface of NDs enable the NDs@POSS nanocomposites to be well-dispersed in organic solvents and polymers for multifunctional applications. The surface coating of NDs with POSS also bring other incidental advantages such as enhanced thermal stability and superhydrophobic of the NDs. NDs@POSS nanocomposites-embedded hybrid films based on polycarbonate and polyvinyl butyral were fabricated by solution blending methods, showing tunable refractive indexes in the range of 1.49–1.61. Furthermore, the powders of NDs@POSS were superhydrophobic with contact angle of water/air of 154°. Liquid marbles formed by coating the water droplet with NDs@POSS were prepared, and the process intensification effects of the NDs@POSS-based miniature reactors for degradation of methylene and fabrication of Ag nanoparticles were also demonstrated, respectively.     

Two Birds One Stone: Graphene Assisted Reaction Kinetics and Ionic Conductivity in Phthalocyanine-Based Covalent Organic Framework Anodes for Lithium-ion Batteries

This work reports a covalent organic framework composite structure (PMDA-NiPc-G), incorporating multiple-active carbonyls and graphene on the basis of the combination of phthalocyanine (NiPc(NH₂)₄) containing a large π-conjugated system and pyromellitic dianhydride (PMDA) as the anode of lithium-ion batteries. Meanwhile, graphene is used as a dispersion medium to reduce the accumulation of bulk covalent organic frameworks (COFs) to obtain COFs with small-volume and few-layers, shortening the ion migration path and improving the diffusion rate of lithium ions in the two dimensional (2D) grid layered structure. PMDA-NiPc-G showed a lithium-ion diffusion coefficient (D_Li⁺) of 3.04 × 10⁻¹⁰ cm² s⁻¹ which is 3.6 times to that of its bulk form (0.84 × 10⁻¹⁰ cm² s⁻¹). Remarkably, this enables a large reversible capacity of 1290 mAh g⁻¹ can be achieved after 300 cycles and almost no capacity fading in the next 300 cycles at 100 mA g⁻¹. At a high areal capacity loading of ≈3 mAh cm⁻², full batteries assembled with LiNi_0.8Co_0.1Mn_0.1O₂ (NCM-811) and LiFePO₄ (LFP) cathodes showed 60.2% and 74.7% capacity retention at 1 C for 200 cycles. Astonishingly, the PMDA-NiPc-G/NCM-811 full battery exhibits ≈100% capacity retention after cycling at 0.2 C. Aided by the analysis of kinetic behavior of lithium storage and theoretical calculations, the capacity-enhancing mechanism and lithium storage mechanism of covalent organic frameworks are revealed. This work may lead to more research on designable, multifunctional COFs for electrochemical energy storage.     

Erratum to: Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

Nano Research - The labels in Fig. 8 in the original version of this article were unfortunately misplaced. The corrected figure is as follow.     

Flexible Cationic Nanoparticles with Photosensitizer Cores for Multifunctional Biomedical Applications

One challenge for multimodal therapy is to develop appropriate multifunctional agents to meet the requirements of potential applications. Photodynamic therapy (PDT) is proven to be an effective way to treat cancers. Diverse polycations, such as ethylenediamine‐functionalized poly(glycidyl methacrylate) (PGED) with plentiful primary amines, secondary amines, and hydroxyl groups, demonstrate good gene transfection performances. Herein, a series of multifunctional cationic nanoparticles (PRP) consisting of photosensitizer cores and PGED shells are readily developed through simple dopamine‐involving processes for versatile bioapplications. A series of experiments demonstrates that PRP nanoparticles are able to effectively mediate gene delivery in different cell lines. PRP nanoparticles are further validated to possess remarkable capability of combined PDT and gene therapy for complementary tumor treatment. In addition, because of their high dispersities in biological matrix, the PRP nanoparticles can also be used for in vitro and in vivo imaging with minimal aggregation‐caused quenching. Therefore, such flexible nanoplatforms with photosensitizer cores and polycationic shells are very promising for multimodal tumor therapy with high efficacy.     

Metal–Organic‐Framework‐Derived Carbon Nanostructure Augmented Sonodynamic Cancer Therapy

Sonodynamic therapy (SDT) can overcome the critical issue of depth‐penetration barrier of photo‐triggered therapeutic modalities. However, the discovery of sonosensitizers with high sonosensitization efficacy and good stability is still a significant challenge. In this study, the great potential of a metal–organic‐framework (MOF)‐derived carbon nanostructure that contains porphyrin‐like metal centers (PMCS) to act as an excellent sonosensitizer is identified. Excitingly, the superior sonosensitization effect of PMCS is believed to be closely linked to the porphyrin‐like macrocycle in MOF‐derived nanostructure in comparison to amorphous carbon nanospheres, due to their large highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap for high reactive oxygen species (ROS) production. The nanoparticle‐assisted cavitation process, including the visualized formation of the cavitation bubbles and microjets, is also first captured by high‐speed camera. High ROS production in PMCS under ultrasound is validated by electron spin resonance and dye measurement, followed by cellular destruction and high tumor inhibition efficiency (85%). This knowledge is important from the perspective of understanding the structure‐dependent SDT enhancement of a MOF‐derived carbon nanostructure.