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The C–H functional groups play a crucial role in reducing electrolyte reduction reactivity and eliminating the trapping effects on Li/Na/K-ions, thereby enhancing the initial coulombic efficiency and reversible capacity.

The prismatic and basal plane surfaces of carbon materials dictate most of their anisotropic physicochemical properties. For many applications where interfacial interactions are key, high-temperature treatments are performed to achieve their graphitization. Such treatment changes edge and basal plane configuration, impacting the energetical behavior of the carbon surfaces, particularly for carbon nanomaterials, with consequences for their properties. Therefore, efforts should be devoted to probing the prismatic and basal plane surfaces of such materials to understand their surface properties for the development of high-performance carbon materials. Herein, we investigate the effect of high-temperature graphitization (3073 K) on the structural, textural, chemical, and magnetic properties of graphitic carbon nanomaterials presenting different prismatic/basal surfaces. The evolution of the prismatic/basal surfaces has been probed by nitrogen adsorption, temperature-programmed desorption, and X-ray photoelectron spectroscopy (XPS). Although these three techniques are in agreement for the starting materials, they diverge in the case of materials that have undergone thermal annealing. This is linked in particular to the formation of loops following the heat treatment, which are identified as belonging to the prismatic surface by XPS and modified the N2adsorptive potentials. Formed small vacancies on closed loops and nonperfect closure of certain loops can contribute to the accumulation of very reactive defects at the loop level. The thermal annealing also has a pronounced influence on the magnetic properties of these materials. Interestingly, we show that a positive correlation exists between the spin density of the annealed graphitic carbons and their prismatic and basal surfaces.

In recent years, significant attention has been directed toward advancing compact, point-of-care testing (POCT) devices to better deliver patient care and alleviate the burden on the medical care system. Common POCTs, such as blood oxygen sensors, leverage electrochemical sensing in their design. However, conventional electrochemical devices typically use Ag/AgCl reference electrodes, which are likely to release trace amounts of silver ions that contaminate the working electrode, causing rapid deterioration of the devices. This study proposes an effective reference electrode using graphene-coated porous silica spheres (G/PSS) with embedded Prussian blue (PB), denoted PB/G/PSS, designed specifically for small oxygen sensors. PB is a redox species that is an improvement over Ag/AgCl since it is significantly less water-soluble than AgCl. Since PB is an insulator, we dispersed PB in G/PSS, well-conductive mesoporous matrices, to ensure contact between PB clusters and the electrolytes. Moreover, the monodispersed, spherically shaped PB/G/PSS is an advantageous medium for fabricating POCT devices by screen printing. In this study, the open-circuit potential of the PB/G/PSS electrode remained stable within 30 mV for 31 days. The small oxygen sensor assembled through screen printing using PB/G/PSS demonstrated stable operation for several days or more. In contrast, a similar sensor with Ag/AgCl reference electrode rapidly deteriorated within a day. This PB/G/PSS reference electrode with improved stability is expected to be an excellent alternative to the Ag/AgCl system for small electrochemical-based POCT devices.

Porous materials synthesized through bottom-up approaches, such as metal–organic frameworks and covalent organic frameworks, have attracted attention owing to their design flexibility for functional materials. However, achieving the chemical and thermal stability of these materials for various applications is challenging considering the reversible coordination bonds and irreversible covalent bonds in their frameworks. Thus, ordered carbonaceous frameworks (OCFs) emerge as a promising class of bottom–up materials with good periodicity, thermal and chemical stability, and electrical conductivity. However, a few OCFs have been reported owing to the limited range of precursor molecules. Herein, we designed a hexaazatrinaphthylene-based molecule with enediyne groups as a precursor molecule for synthesizing an OCF. The solid-state Bergman cyclization of enediyne groups at a low temperature formed a microporous polymer and an OCF, exhibiting redox activity and demonstrating their potential for electrochemical applications. The microporous polymer was used as an active material in sodium-ion batteries, while the OCF was used as an electrochemical capacitor. These findings illustrate the utility of the Bergman cyclization reaction for synthesizing microporous polymers and OCFs with a customizable functionality for broad applications.

High-temperature annealing is an effective way to heal the defects of graphene-based nanocarbons and enhance their crystallinity. However, the thermally induced vibration of the graphene building blocks often leads to unfavorable micro-, nano-structural evolution including layer stacking. Herein, the key structural factors to achieve highly crystalline graphene frameworks with desired microstructures upon annealing at 1800 °C is revealed. The structural changes of fullerenes, single-walled carbon nanotubes, and graphene-based porous frameworks are precisely analyzed by their structural parameters, such as the total number of graphene edge sites and precise graphene stacking structures, using a novel advanced vacuum temperature-programmed desorption technique up to 1800 °C. The stacked structure is differentiated into loose and tightly stacking, where the loosely stacked structure is found to induce further stacking at high-temperature. Moreover, a graphene framework with an inner space size of greater than 4–7 nm is beneficial to avoid structural change upon high-temperature annealing. These findings offer both a fundamental understanding of the solid-state chemistry of nanocarbons under high temperatures and a viable strategy for engineering edge-site free graphene frameworks with pre-designed microstructures.The structural retention degree (SRD) is established as a numerical descriptor for the thermal stability of carbon materials. The loosely stacked structure and high surface curvature (represented by inner space size <4–7 nm) are responsible for diminished SRD of nanocarbons, as they are able to trigger the stacking of basal plane during high-temperature annealing.

Lithium–oxygen batteries show great promise as energy storage devices but suffer from high overpotential, which is a major cause of poor cycle stability. To reduce the overpotential, catalysis on a carbon-based cathode is crucial. This work examines the sequential catalysis of a carbon-based cathode containing basal defects and Ru nanoparticles. A new type of carbon cathode is fabricated by dispersing Ru nanoparticles onto a highly mesoporous carbon framework of mainly single-walled curved graphene, which has abundant basal defects but few edge sites. This novel cathode exhibits unique sequential catalysis by forming two distinct morphologies of lithium peroxide in the discharge process. These two morphologies are decomposed at different potentials during charging. A comprehensive analysis, including in situdifferential electrochemical mass spectrometry, reveals that the low and high-potential charging plateaus are induced by two different catalytic mechanisms derived from basal defects and Ru nanoparticles, respectively. Interestingly, these two mechanisms do not interfere with each other but act sequentially, reducing the overpotential and thus enhancing the cycle stability.

Rigid three-dimensional π-skeletons are useful building blocks for organic porous materials but only a few types of compounds are available as compared with a variety of planar building blocks. Herein, we report that hexa-aminated trinaphtho[3.3.3]propellane was readily prepared by a two-step reaction sequence from a non-functionalized propellane in moderate yield and was active toward condensation with boronic acids and aldehydes. Solvothermal condensation with terephthalaldehyde gave an amorphous polymeric solid with moderate BET surface area, different from precursor molecules. The solid displayed good adsorption capacities for hydrocarbon gases and vapors. Because of multiple CH/π interactions, the adsorption was efficient even at low-pressure for n-butane and larger alkanes, providing good selectivity over smaller alkanes.Hexa-aminated trinaphtho[3.3.3]propellane was newly developed as a rigid three-dimensional building block with extended π-surfaces. Condensation with terephthalaldehyde gave a porous polymer as an amorphous solid, which showed high adsorption capacities for alkane gases and vapors with strong preference for larger n-alkanes due to multiple CH/π interactions.

A new type of pyrene–thiol derivative-modified Pd nanoparticle (NP) catalyst on a carbon black support for the efficient semihydrogenation of alkynes to alkenes is reported herein. Colloidal Pd NPs surrounded by pyrene–thiol modifiers were prepared using the two-phase Brust method followed by impregnation of carbon black materials. Based on the structural characterization of the prepared catalyst (PyC12S-Pd/VC) by NMR, UV–vis, FT-IR, TEM, HAADF-STEM, Pd K-edge XAFS, XRD, N2adsorption, and XPS, we show that highly dispersed Pd NPs are immobilized on the catalysts via π–π interaction between pyrene groups bound to the Pd NPs and carbon black supports. PyC12S-Pd/VC efficiently catalyzes the alkyne semihydrogenation reaction while maintaining high alkene selectivity; an alkene selectivity of 94% is attained at 98% conversion after 5 h of reaction, and the selectivity was retained around 80% in 10 h of reaction. This performance is superior to that of a catalyst without pyrene groups and that of a commercial Lindlar catalyst. The steric hindrance of pyrene groups restricts access of the substrates to Pd NP surfaces, suppressing the unfavorable overhydrogenation of alkenes to alkanes, which is revealed by the solvent and substrate dependency on the catalytic performance and a DFT calculation study. Furthermore, the high selectivity and stability of PyC12S-Pd/VC are caused by the strong interaction between pyrene groups and carbon supports, which prevents the separation of pyrene modifiers and the leaching or sintering of Pd NPs during the catalytic reaction. It is demonstrated that the combination of Pd NPs, pyrene–thiol modifiers, and carbon supports offers high activity, alkene selectivity, and stability in the semihydrogenation reaction.

Visible-light boosting chemical reactions by surface plasmon resonance (SPR) have recently received much attention in photocatalysis. Although multiple types of plasmonic catalysts have been developed, the efficient utilization of SPR-induced hot-electrons remains to be a challenging task due to their ultrafast decay. In this study, structure-controlled Pd-graphene-Au nanorod nanocomposite catalysts are fabricated for maximizing hot-electron utilization in SPR-enhanced reactions. The characterization confirmed that highly dispersed Pd clusters were deposited on a homogeneous reduced graphene oxide (rGO) layer-coated Au nanorods. The catalytic activity in the Suzuki–Miyaura coupling reaction was highly enhanced under visible-light irradiation due to the SPR of the Au nanorods, whose performance was superior to that without an rGO layer. Further experimental and calculation study demonstrated that the electro-conductive rGO layer plays a crucial role as an electron mediator for promoting hot-electron transportation from Au to Pd, which resulted in the reaction acceleration.

Carbon materials have been extensively studied for several decades as catalytic supports because of their high surface area and porous structures. However, carbon black supports, such as Ketjen black or Vulcan XC-72, have rarely been utilized for organic syntheses, though they have recently been widely studied in electrocatalysts. In this study, we examined Ketjen black with high surface area and high pore volume as a support for Ru nanoparticles (NPs) in the catalytic transfer hydrogenation (CTH) reaction. The performance of the Ru NP catalyst supported on Ketjen black was superior to that on other carbon supports. The catalysts were structurally characterized using X-ray diffraction, X-ray absorption fine structure, transmission electron microscopy, CO chemisorption, and N2adsorption/desorption measurements. A clear correlation was observed among the micro- and mesopore volume, the adsorption capacity of reactant, and the catalytic activity, and therefore, micro- and mesopores in Ketjen black were found to adsorb the reactant, acetophenone, and thus play a crucial role in achieving high catalytic performance in the CTH reaction.

The structure–activity relationship of carbon-supported Co catalysts was investigated in solvent-free aerobic oxidation of ethylbenzene under microwave irradiation. A single-site Co species show specifically high catalytic activity under microwave irradiation compared to conventional heating, while the oxidation is not accelerated by microwave when Co nanoparticle catalysts are used.The single-site Co species show specifically high catalytic activity in the solvent-free aerobic oxidation under microwave irradiation compared to the conventional heating, while the oxidation is not accelerated by microwave when Co(salen) or Co nanoparticle catalysts are used.