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Dodecahydro-N-ethylcarbazole (12H-NEC) is considered as a highly promising liquid organic hydrogen carrier, but its commercial application is constrained by the requirement of large amounts of precious metal catalysts for dehydrogenation. Herein, Pd nanoclusters with an average particle size of 1.1 nm supported on amine groups modified carbon blacks (Pd/N–C HNO3) are developed to efficiently catalyze the dehydrogenation of 12H-NEC with a low loading of Pd (2.2 wt%, 0.12 mol%). Induced by the nitrogen doping in the carbon black, the d- band center of the Pd (111) surface shifts from −1.64 eV to −1.53 eV, resulting in the electron-deficient structure of thus-formed Pd nanoclusters owing to the electron transfer from Pd to N atoms and uniform distribution of Pd nanoclusters inside of carbon blacks. This electron transfer effectively tunes Pd0:Pdδ+ ratio for enhancing the adsorption of reactant species of 12H-NEC on the surface of Pd nanoclusters and hence facilitates the catalytic role of Pd nanoclusters in enhancing the hydrogen desorption performance of 12H-NEC. As a result, every step of the dehydrogenation of 12H-NEC under the catalysis of Pd nanoclusters on the nitrogen-doped support exhibits lower ΔG values compared to the non-doped support, which provides direct evidence to the important role of the nitrogen doping of the catalyst support in improving the dehydrogenation performance of 12H-NEC on the Pd surface. Therefore, a hydrogen release capacity of 5.60 wt% with 100% conversion and a selectivity of 90% could be obtained for 12H-NEC under the catalysis of Pd nanoclusters supported on amine-functionalized carbon black at 453 K with a low precious metal dosage (0.12 mol%). [Display omitted] •Pd nanoclusters with an average particle size of 1.1 nm supported on amine groups modified carbon blacks are developed. • A hydrogen release capacity of 5.60 wt% is obtained for 12H-NEC with an ultralow Pd dosage (0.12 mol%). • A H 2 release amount of 5.49 wt% with a capacity retention of 96% is achieved for 12H-NEC after five cycles for 40 h. • The d- band center of the Pd (111) surface shifts from −1.64eV to −1.53eV upon nitrogen doping. • DFT calculations reveal that ΔG for the dehydrogenation of 12H-NEC by the catalyst is decreased upon nitrogen doping. [ABSTRACT FROM AUTHOR]

MoSe2 as one graphene-like 2D transition metal selenide has attracted great attention. However, its application for the hydrogen evolution reaction (HER) is still restricted by the poor electrical conductivity and structural restacking. In this work, an excellent electrocatalyst for hydrogen production is developed based on the in situ synthesis of V-doped MoSe2 confined on carbon black nanoparticles (denoted as V-MoSe2/CB) via a sol–gel process. The characterization results show that the carbon black nanoparticles can protect the V-MoSe2 nanosheets from agglomeration, resulting in ultra-thin thickness and short vertical lattice arrays. Meanwhile, density functional theory (DFT) calculations indicate that vanadium doping can optimize the electronic structure of MoSe2. Accordingly, compared to the pure MoSe2, V-MoSe2 and MoSe2/CB electrocatalysts, V-MoSe2/CB exhibits improved electrocatalytic activity with a small overpotential of 166 mV at −10 mA cm−2 and a small Tafel slope of 65 mV dec−1. This work paves a new way for improving the HER performance through synergistic morphology, structure and electronic regulation. [ABSTRACT FROM AUTHOR]

High Resolution Transmission Electron Microscopy (HR TEM) is used to identify the size, shape, and interface structure of platinum nanoparticles and carbon support of a fuel cell catalyst. Using these insights, models accessible to quantum chemical methods are designed in order to rationalize the observed features. Thus, basal plane and prism face models of the carbon black material are considered, interacting with Pt clusters of sizes up to 1 nm. Particular attention is paid to the electronic structure of the carbon support, namely, the radical character of graphene zig-zag edges. The results show that a stronger interaction is found when the nanoparticle is at the zig-zag edge of a basal plane due to the combination of dispersion interaction with the support structure and covalent interaction with carbon atoms at the edge. In this case, a distortion of both the Pt nanoparticle and the carbon support is observed, which corresponds to the observations from the HR TEM investigation. Furthermore, the analysis of the charge transfer upon interaction and the influence of the potential on the charge states and structure is carried out on our model systems. In all cases, a clear charge transfer is observed from the carbon support to the Pt nanoparticle. Finally, we show that changing the potential not only can change the charge state of the system but can also affect the nature of the interaction between Pt nanoparticles and carbon supports. [ABSTRACT FROM AUTHOR]

[Display omitted] • Severe carbon accumulation was observed on black phosphorus flake under synchrotron radiation. • The carbon accumulation was hardly observed on MoS 2 flake due to its lower surface reactivity. • Our statistical approach revealed beam-induced surface modification quantitatively. • Studying reactive surface must require careful examination of beam-induced surface modification. • Careful selection of synchrotron beam power density would prevent reported carbon accumulation. Two-dimensional (2D) materials, such as black phosphorus (BP) and transition metal dichalcogenide, recently gained much interest due to their unique electronic, photonic, and mechanical properties. Synchrotron-based scanning photoelectron microscopy (s -SPEM) with a spatial resolution (down to 70 nm) has actively applied for exploring the relationship between chemical information and electronic structure of 2D materials on concerned local surface area. Here, we compare carbon accumulation on the surface of BP and MoS 2 during synchrotron beam irradiation. During the BP characterization, carbon was rapidly accumulated on BP surface as irradiation progress, while MoS 2 demonstrated better resistance to carbon accumulation in comparison to BP. Our work suggests that the higher surface reactivity of BP results in the formation of even BP-carbide structure upon the irradiation, while MoS 2 with relatively low reactivity is rather stable against carbon accumulation. This photon-induced carbon accumulation causes the misleading result of surface chemical information and electronic structure in highly reactive 2D materials or nanostructures. [ABSTRACT FROM AUTHOR]

Hollow graphitic carbon nanoparticles (HGCNs) obtained by catalytic graphitization of acetylene carbon black (ACB) were investigated using ultra-soft X-ray emission spectroscopy. The electronic structures of the ACB HGCNs were compared with those of HGCNs obtained from iron carbide-filled carbon nanocapsules (Fe3C@CNCs) and Q-graphenes. The occupation of the π sub-band decreased in the following sequence: Fe3C@CNC HGCNs > ACB HGCNs > Q-graphenes. This sequence can be explained by changes in the occupations of the C2p states due to the formation of bonds between carbon and residual metal atoms within the HGCNs. It was also found that the contribution of the overlapping ofppπ+ppσ-states in the ACB HGCN walls toward the spectra of the HGNCs was greater in comparison with the reference Q-graphenes. It was established that ACB was not fully transformed into the HGCNs. Scanning and transmission electron microscopy methods were used to study the spatial structures and morphologies of the fabricated HGCNs. [ABSTRACT FROM PUBLISHER]

Abstract: Two commercial carbon blacks, Ketjen black EC600JD (KB600) and Super P with quite different porosity parameters, are used for the cathode of a lithium-air battery. With high specific pore volume, KB600 shows a higher weight specific capacity. However, Super P exhibits a super high volume specific capacity, about 7 times higher than that of KB600, ascribed to its higher proportion of pores with suitable size for the deposition of solid products. The effects of O2 partial pressure and discharge rate on the specific capacity are investigated, combined with characterizations of contact angle and the structure of the electrodes. It is demonstrated that the Super P electrode possesses better O2 transport that improves the use of the whole electrode volume, and the special mechanism of O2 diffusion in the Super P electrode is proposed. By mixing KB600 with Super P with a weight ratio of 5:1, an electrode is obtained that exhibits increased O2 transport. The weight specific capacity is 1219 mAh g−1, about 1.2 times higher than that of KB600. [Copyright &y& Elsevier]

Abstract: Soft X-ray emission and absorption spectroscopy methods were used in the present work to study experimentally the electronic structure of the dense amorphous carbon phase synthesized in a mixture with diamond as a result of shock compression of carbon black. The X-ray emission C Kα bands, representing the energy distribution of the C 2p-like states, have been recorded for the amorphous carbon phase and, for comparison, for diamond, lonsdaleite, graphite, and carbon black. For the amorphous carbon phase, diamond and lonsdaleite the spectra of quantum yields of the X-ray photoeffect in the area of the C K absorption edge have been recorded as well. Total and partial densities of states of the carbon H-6 and bct-4 phases, diamond and lonsdaleite have been calculated using the first-principles self-consistent full potential linearized augmented plane wave (FP-LAPW) method. Comparison on a common energy scale of the X-ray emission C Kα bands and C K quantum yields of the dense amorphous carbon phase as well as the theoretical curves of partial C 2p-like states of the carbon H-6 and bct-4 phases reveals that, the electronic structure of the amorphous carbon phase under consideration is well described by that of the carbon bct-4 phase. The experimental X-ray emission and absorption spectroscopy data indicate that the amorphous carbon phase studied is metallic, being in agreement with the results of the theoretical FP-LAPW calculations. [Copyright &y& Elsevier]