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Abstract: The effect of the commonly used 55,000 M w (PVP55) and a heavier chain of 360,000 M w (PVP360) on commercial 40wt% Pt/C were probed using electrochemical methods and in situ SEIRAS experiments during the MOR and related gaseous CO oxidation. The polymer-modified samples exhibited an enhanced long-term CO tolerance with a small hindrance to the intrinsic activity of Pt/C. Increased water adsorption in the presence of polymer was observed to coincide with the oxidation of adsorbed CO and was related to the desorption of the surface-bound carbonyl of PVP via in situ SEIRAS. The notable differences between the adsorbate trends are indicative of adsorbed polymer interactions with the surface, but more interestingly is the strong dependence of the polymer molecular weight M w that led to qualitatively different behavior. Understanding the effects of adsorbed PVP on electrocatalytic reactions is of fundamental and practical importance due to its widespread use in synthesized NPs targeted for fuel cell applications. [Copyright &y& Elsevier]

Abstract: Ni-based industrial alloy samples (INCONEL® 601) were subjected to oxidizing conditions, followed by exposure to a high carbon activity gaseous mixture containing 10% CO in Ar at 550°C in order to reveal factors critical to the initial carbon-formation. Fresh and treated samples were studied via optical-microscopy, SEM, Auger depth-profile analysis, TEM and EPMA. The results show that the extent of carbon formation is dependent on the oxidation parameters, since these affect both the composition and the structure of the 20-60nm thick oxide layer formed. A high oxygen partial pressure during oxidation appears to promote inclusion of Ni or Fe species in the oxide, which subsequently reduce and catalyse the growth of carbon filaments. Surface pre-treatment (i.e. polishing before oxidation) is also found to affect the carbon formation. [Copyright &y& Elsevier]

Abstract: The impact of some engineering aspects such as space velocity, catalyst metal loading, hydrogen, and temperature on carbon nanotube (CNT) production rate, productivity, and morphology in carbon monoxide disproportionation has been studied. The morphology and quality of the CNTs produced were examined by high resolution transmission electron microscopy (TEM). It was found that space velocity and metal loading have significant effects on the production rate and CNT productivity. The presence of H2 dramatically increased the productivity, but altered the CNT structure. The synthesis temperature also influenced the carbon productivity and structure. The results were interpreted according to the traditional model for CNT growth, and the implications for large-scale CNT production were suggested. [Copyright &y& Elsevier]

The surface curvature of the carbon nanofibers (CNF) and the strong interaction between the metal and the graphene edges cause local deformation of metal nanoparticles, and thereby inducing a high degree of microstrain. Such lattice expansion has been shown to increase the activity of Ni crystals. This provides new opportunities to manipulate the catalytic activity of the metal. [Copyright &y& Elsevier]

Highlights: [•] Adsorption of a Pt atom on polyaromatic hydrocarbons is investigated. [•] The Pt–C charge transfer depends on the Pt–C bond lengths. [•] Dispersion and relativistic contribution are crucial for Pt–C DFT calculations. [•] SSB-D functional with ZORA is recommended for Pt/C calculations. [Copyright &y& Elsevier]

Abstract: PtRuRE/C catalysts were prepared through doping the commercial JM PtRu/C catalyst with rare earth (RE=La, Eu, Gd, Y, Sm and Er). The doping was conducted by chemical reduction and sintering treatment methods. The catalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the rare earth doping did not significantly change the average size of the JM PtRu/C particles, and modified the PtRu surface with two element states of the metal and oxide. Studies of cyclic voltammetry and chronoamperometry indicated that the electrocatalytic activity of PtRuRE/C catalysts was higher than that of the JM PtRu/C for methanol oxidation (except for PtRuGd/C), generating a decreasing order of PtRuEu/C>PtRuEr/C>PtRuY/C>PtRuSm/C>PtRuLa/C>JM PtRu/C>PtRuGd/C. It has revealed that among the PtRuRE/C catalysts the PtRuEu/C exhibited the best performance. In addition, the reaction process of methanol electrocatalytic oxidation on several catalysts was investigated by in situ FTIR spectroscopy at molecule level. The results demonstrated that the adsorbates derived from methanol dissociative adsorption on the catalysts were the linear-bonded CO (COL), and the CO-tolerance performance of PtRuRE/C catalysts was better than JM PtRu/C. It has revealed also that the electronic effect of rare earth plays an important role in the catalytic performance of PtRuRE/C catalysts for methanol electrooxidation. [Copyright &y& Elsevier]

Abstract: Carbon nanofibers (CNFs) with different microstructures were synthesized as the support of Pt catalyst for decalin dehydrogenation to evolve pure hydrogen. The results show that in a liquid-film state at the temperature of 240°C for reactor external heating, 5wt% Pt catalyst supported on platelet CNFs gives a TOF of 732.4mol H2/mol metal in 2h. The microstructure of CNFs and the metal particle size have great impact on the performance of the catalyst for the reaction. [Copyright &y& Elsevier]

Abstract: First-principles calculations based on density functional theory and the generalized gradient approximation have been used to study the C chemisorption and diffusion on the surface and in the subsurfaces of Ni(111). The threefold Hcp site is observed to be preferred by the C adsorption on Ni(111) surface while in the subsurfaces, the octahedral site is more energetically favorable than the tetrahedral site and all surface adsorption sites. The calculated binding energies have been compared with the previous experimental and theoretical results and good agreement is found. Minimum energy paths for the C diffusion between different adsorption sites are also investigated using the nudged elastic band method. It is predicted that if the C surface diffusion rate is higher than the production rate of C atoms during the growth of carbon nanofibers and the C concentration is low at the Ni surface, the generated C atoms are likely to diffuse on the catalyst surface predominantly because of the lowest energy barrier, while if the generated C production rate is higher and some adsorption sites are blocked by the accumulated carbon, the C atoms may diffuse both on the surface and in the subsurfaces simultaneously. [Copyright &y& Elsevier]

Using polydopamine as nitrogen-doped carbon precursors, adsorbent and reducing agent of HAuCl 4 , nitrogen and Au nanoparticle could be in situ doped and surface modified successively into/onto carbon spheres. The conductivity, electrons transfer ability, and electrocatalytic activity of carbon sphere were improved by the synergistic effect of surface modification with Au nanoparticle and nitrogen doping and then the sensitivity of this electrochemical sensor was enhanced. The synthesized nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Based on the difference of adsorption rates and oxidation potentials, both nitrophenol isomers ( o -nitrophenol, m -nitrophenol, p -nitrophenol) and dihydroxybenzene isomers (hydroquinone, catechol, resorcinol) could be identified, separated successfully, and determined simultaneously by differential pulse voltammetry. This proposed method with wide linear range (0.05–600 μmol L −1 ) and low detection limit (24–98 nmol L −1 ) was successfully applied for simultaneous detection of nitrophenol and dihydroxybenzene isomers in wastewater and natural water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical hyperporous carbon (HHPC) was derived from phenylenediamine residue. • One-step "carbonization-casting-activation" strategy was used for HHPC synthesis. • The HHPC shows superior chloroxylenol adsorption capacity. • In-situ N/O co-dopped carbon surface enhances the adsorption of chloroxylenol. The chloroxylenol (PCMX) has shown well virucidal efficacy against COVID-19, but the large-scale utilization of which will undoubtedly pose extra environmental threaten. In the present study, the recycled industrial phenylenediamine residue was used and an integrated strategy of "carbonization-casting-activation" using super low-dose of activator and templates was established to achieve in-situ N/O co-doping and facile synthesis of a kind of hierarchical hyperporous carbons (HHPC). The sample of HHPC-1.25–0.5 obtained with activator and template to residue of 1.25 and 0.5 respectively shows super-high specific surface area of 3602 m2/g and volume of 2.81 cm3/g and demonstrates remarkable adsorption capacity of 1475 mg/g for PCMX in batch and of 1148 mg/g in dynamic column adsorption test. In addition, the HHPC-1.25–0.5 exhibits excellent reusability and tolerance for PCMX adsorption under various ionic backgrounds and real water matrix conditions. The combined physio-chemistry characterization, kinetic study and DFT calculation reveal that the enhanced high performances originate from the hierarchical pore structure and strong electrostatic interaction between PCMX and surface rich pyridinic-N and carbonyl groups. [ABSTRACT FROM AUTHOR]

Abstract: A HCHO reduction method was used to prepare Pt/CNF catalysts for decalin dehydrogenation to produce pure hydrogen. The effects of pH adjustment, Pt loading and especially reduction temperature were discussed based on zeta potential and metal particle size measurement and XPS and TPR characterization. It was shown that the efficiency of Pt loading was significantly enhanced by adjusting the pH and the activity of the Pt/CNF catalyst was consequently improved. Higher Pt loading did not lead to better catalyst activity because of the growth of Pt particles. Increasing the reduction temperature promoted the reduction of Pt species but not changed the particle size. Complete reduction of the Pt catalyst was preferred to increase the catalyst activity. Excellent activity and selectivity were observed for the catalyst reduced at 80°C with a real Pt loading of 5.40wt.%, yielding 729.9mol H2/mol Pt in 2h. [ABSTRACT FROM AUTHOR]

Abstract: 5wt% Pd catalysts supported on platelet carbon nanofibers has been prepared by incipient wetness impregnation. Both the calcination and the reduction temperature have a significant effect on the dispersion of palladium and it was found that about 3nm sized Pd nanoparticles can be obtained at a calcination and reduction temperature of 250°C and 150°C, respectively. Pd catalysts have been applied to catalyze Heck reactions of various activated and non-activated aryl substrates. The activity increased exponentially with a decrease in Pd particle size. The high surface area, mesoporous structure of carbon nanofiber and highly dispersed palladium species on carbon nanofibers makes up one of the most active and reusable heterogeneous catalysts for Heck coupling reactions. Pd nanoparticles supported on platelet CNFs appear to be an excellent catalyst due to high activity, low sensitivity towards oxygen, almost no or low issues with leaching and high stability in multi-cycles. [Copyright &y& Elsevier]

Abstract: The surface properties of fishbone (FB) carbon nanofibers (CNFs) were altered. This was achieved by H2O-plasma treatment (FB-plasma) and oxidation in HNO3 (FB-HNO3). By zeta-potential measurements, the surfaces of as-grown and acid treated CNFs were found to be negatively charged at all pHs. Meanwhile, basic entities were introduced by H2O-plasma treatment, indicated by an isoelectric point of pH 4.6. Ultraviolet–visible measurements indicated the successful deposition of negatively charged Au colloids on FB-plasma, and incomplete deposition on FB-HNO3. The nature of the basic sites accommodating colloid deposition is discussed based on X-ray photoelectron spectroscopy (XPS) results. The XPS study indicated significant differences in the type and amount of surface groups. Also, a variation in the fraction of defect and/or edge sites was found. The possible sites responsible for colloid immobilization are discussed based on the XPS results. Plasma treatment is demonstrated as a simple and effective procedure for altering the surface characteristics of CNFs. [Copyright &y& Elsevier]

Abstract: The rational design of the carbon nanofiber catalysts for oxidative dehydrogenation of ethylbenzene (ODE) has been discussed based on a reviewed reaction mechanism. The synthesized carbon nanofibers with systematically varied graphitic platelet orientations have been used as a model system for the rational catalyst design, in respect to the carbon nanofiber properties such as the amount of basic groups, the crystallinity, and the ratio between the prismatic area and the basal plane area. Well defined carbon nanofibers have been synthesized by hydrocarbon or carbon monoxide decomposition on the sub-iron group catalysts and at selected preparation conditions. The catalytic test in a fixed bed reactor at a temperature of 400°C shows that the stable activity and selectivity can be obtained on the well-defined carbon nanofibers catalysts. Removing the residual metal in carbon nanofibers does not evidently influence the catalytic behavior whereas the lower conversion of ethylbenzene can be observed on the high-temperature treated carbon nanofiber samples. No clear evidences are found for the catalytic behavior being related to the surface area and graphitization degree of carbon nanofibers. The basic oxygen-containing groups are identified as the active sites by TPD–MS and a special method suggested by Boehm. The ratio between the prismatic surface area and the basal area has been identified as the most important parameter for the rational catalyst design. The fish-bone catalysts CNF 20 seems to be the best catalyst in the samples studied in the present work, due to the large number of basic edge groups, the optimum ratio between the prismatic and basal plane area. It can result in a delicate balance in the redox catalytic cycle. As a consequence, the formation of CO2 can be reduced. [Copyright &y& Elsevier]

Abstract: Nanocomposite catalysts containing carbon nanofiber (CNF) and Cu-Ce-Zr mixed metal oxide (MMO) have been prepared by homogeneous co-precipitation with urea. The water-gas shift (WGS) reaction has been used as test reaction. The CNF-containing nanocomposite catalysts exhibit similar overall catalytic activity and stability as the corresponding CNF-free catalyst. Thirteen weight percent of the MMO could be replaced by CNF without decreasing the overall activity and stability of the catalyst. The specific activity of the nanocomposites based on the total metal oxide content is similar or higher than the activity of the CNF-free material, depending on the CNF content. Similar activation energies are, however, obtained for the CNF-free and CNF-containing materials. We cannot exclude that the CNF material acts as reaction promoter under certain conditions, but suggest that the impact of CNF addition on the precipitation of the mixed oxide particles, and hence the catalytic activity relative to the CNF-free MMO, should also be considered. CNF may be regarded as inert dispersing agent material improving the precipitation of the MMO under conditions where the co-precipitation of the MMO precursors does not result in materials with high surface area. [Copyright &y& Elsevier]

Abstract: Catalytically grown carbon nanofibers, a novel mesoporous carbon material for catalysis, were synthesized by the decomposition of carbon-containing gases (CH4, C2H4 or CO) over supported nickel-iron alloy and unsupported iron. It was shown that the structures of as-synthesized and modified CNFs, including the arrangement of the graphenes in CNF, and the crystallinity and texture of CNF depended on the catalyst composition and the type of carbon-containing gas. Three types of CNFs with different microstructures were obtained: platelet CNF (Fe–CO), fishbone CNF (supported Ni–Fe alloy-CH4, C2H4 or CO) and tubular CNF (supported Ni–CO). All the CNFs were mesoporous carbon materials possessing relatively high surface areas (86.6–204.7m2/g) and were highly graphitic. Purification with acid-base treatments or high temperature treatment removed the catalyst residue without changing the basic structures of the CNFs. However, annealing significantly decreased their surface areas through the formation of loop-shaped ends on the CNF surfaces. Oxidative modification in the gas and liquid phases changed the structures only slightly, except for oxidation in air at 700°C. The structures and textures were studied using SEM, TEM, XRD, BET and TGA. [Copyright &y& Elsevier]

TEM image of 3D pomegranate-like core@shell porous carbon structure and their comparison figure with the previous reported capacitance values of porous carbon materials. • A functionalized N and O co-doped three-dimensional hierarchical pomegranate-like porous carbon was rationally synthesized. • The hierarchical porous structure, high packing density and enriched N and O functional groups are crucial. • The symmetric suporcapacitor with the pomegranate-like porous carbon boots a high gravimetric (volumetric) energy density. Recently, the heteroatom-enriched porous carbons have received considerable attention on the research of electrodes with high gravimetric capacitances for supercapacitors (SCs). However, their relatively low volumetric capacitances have limited their practical applications due to very low packing density and poor ion diffusion at high mass loadings. In this study, by means of a facile modified chemical activation route, a functionalized N and O co-doped three-dimensional (3D) hierarchical pomegranate-like porous carbon (PPC) was rationally synthesized. First, A core–shell structured precursor composite for PPC was constructed. The polypyrrole (PPy) with the desired functional group was adopted as the precursor of the pomegranate-like core, and the polyacrylamide (PAM) hydrogel as the precursor of the pomegranate-like shell (designated as PPy/PAM). Then, after calcination of the PPy/PAM hydrogel precursor composites, a novel 3D hierarchical PPC was achieved. The as-obtained PPC offers short diffusion paths of ions, increases packing density and provides abundant active sites for pseudocapacitance by increasing self-oxygen–nitrogen-doped content. The performance tests of SC with PPC manifest that at 156 W kg−1 (109.7 W L-1), boosted energy density of 11.5 Wh kg−1 (8.05 Wh L-1) can be achieved. The as-obtained PPC is the promising electrode material of high-performance SCs for practical applications. [ABSTRACT FROM AUTHOR]