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The high activity electrocatalysts with low cost are crucial for large-scale direct alcohol fuel cells (DAFCs) applications. In this study, the "self-doping-defects" mesoporous carbon (SDMC) as support of uniformly-dispersed Pd nanoparticles (Pd/SDMC) was prepared for high active electrooxidation by a simple route without additional surfactant and acid treatment. According to the mutually corroborated experimental and theoretical calculation results, our route can significantly increase the carbon defect, which is conducive to the anchoring and uniform distribution of Pd nanoparticles. Meanwhile, the uniquely and hierarchically mesoporous nanostructure of SDMC provides abundant pathways for mass transport in the electrooxidation reaction. Benefitting from the above advantages, Pd/SDMC exhibits superior activity than commercial Pd/C and previously reported carbon-based electrocatalysts. The mass activities and specific activities of Pd/SDMC toward ethanol oxidation reaction (EOR) are 3404.3 mA mg−1, 4.48 mA cm−2, respectively. The mass activities and specific activities of Pd/SDMC for ethylene glycol oxidation reaction (EGOR) are 4002 mA mg−1, 5.26 mA cm−2, respectively. We believe that the facile strategy to synthesis mesoporous carbon with "self-doping" defects would promote large-scale DAFCs applications in the future. • The mesoporous carbon with "Self-Doping" defects was prepared via a simple method. • Pd nanoparticles were uniformly dispersed on the SDMC by a simple method without surfactant. • The Pd/SDMC enhances the catalytic of EOR and EGOR. [ABSTRACT FROM AUTHOR]

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: Carbon nanofibers (CNFs) have been used as templates for manipulating the properties of Ni catalyst particles. Both incipient wetness impregnation and deposition–precipitation have been used to prepare the catalysts. Relatively well-dispersed Ni nanoparticles have been prepared on oxidised CNFs by incipient wetness impregnation. The diameter of the CNFs has been shown to have a significant effect in determining the Ni crystal size. In addition, CNFs are suitable templates to induce microstrain to metal particles. Such microstrain has significant effects on the activity of Ni crystals during ethane hydrogenolysis. This provides new opportunities to manipulate the crystal size and activity of the metal by selecting proper carbon nanofibers as support. TPO has been demonstrated as a powerful tool to study the CNF supported catalyst and to provide information on Ni loading and relative activity of NiO for CNF oxidation. [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: [•] Magnetite/reduced graphene oxide (MRGO) nanocomposites are synthesized. [•] MRGO is used as an adsorbent for determination of isocarbophos. [•] Effects of synthesis conditions on adsorption performance are well investigated. [•] MRGO shows good extraction ability, reuse stability and manipulative convenience. [•] Different sample matrices have little interference with the performance of MRGO. [Copyright &y& Elsevier]

Abstract: Rh supported on Zr x Ce1−x O2–Al2O3 (x =1, 0.5, 0.25, 0) catalysts are studied for catalytic partial oxidation of methane to synthesis gas. Alumina based nanocomposites are prepared through a citrate mediated route by modifying the alumina support with cerium and zirconyl nitrates via a simple evaporation-drying or a spray drying method. The effect of the commercial alumina types and the preparation method on the structure and thermostability of the nanocomposites has been studied based on the characterization by XRD, Raman spectroscopy, DTA, TEM and nitrogen adsorption–desorption measurements. Evonik Aeroxide AluC based nanocomposites prepared by spray drying give the highest thermostability concerning the sintering and phase transformation of the composites. Rh with a 0.1 or 0.5wt.% loading is deposited on these nanocomposites by incipient wetness impregnation method. After calcination at 1173K for 5h, these nanocomposites supported Rh catalysts are tested in the fixed-bed reactor for methane partial oxidation. It is found that the smaller c-CeO2 crystal size in the nanocomposites, i.e. the higher oxygen vacancy concentration, would be responsible of the lower ignition temperature due to the enhanced reducibility, whereas the higher Rh dispersion would be responsible of the higher methane conversion and selectivity to synthesis gas. Additionally the Rh dispersion is found to be linked to the BET surface area. The stability of the nanocomposites is also studied under reaction conditions. [Copyright &y& Elsevier]

Abstract: A nonenzymatic electrochemical method was developed for glucose detection using an electrode modified with palladium nanoparticles (PdNPs)-functional carbon nanotubes (FCNTs). PdNPs were homogeneously modified on FCNTs through a facile spontaneous redox reaction and characterized by transmission electron microscopy. Based on the voltammetric and amperometric results, PdNPs efficiently catalyzed the oxidation of glucose at 0.40V in the presence of 0.2M NaCl and showed excellent resistance towards poisoning from such interfering species as ascorbic acid, uric acid, and p-acetamidophenol. This anti-poisoning ability was investigated using analysis of the electrocatalytic products by in situ subtractively normalized interfacial Fourier transform infrared reflection spectroscopy, and the results indicated that no strongly adsorbed COad species could be found in the oxidation products, which was obviously different from the results obtained using Pt-based electrodes. In order to verify the sensor reliability, it was applied to the determination of glucose in urine samples. The results indicated that the proposed approach provided a highly sensitive, wide linear range, more facile method with good reproducibility for glucose determination, promising the development of Pd-based material in nonenzymatic glucose sensing. [Copyright &y& Elsevier]

• Small Ni particles exhibit higher steam methane reforming activity than large ones. • The size-dependent activity of Ni catalysts is related to the surface-dependent activity. • Ni(2 1 1) is the most active surface for steam methane reforming. • Decreased Ni(2 1 1) surface fraction results in reduced Ni activity as size increases. Fundamental understanding of the size-dependent activity is essential to harness powers of the nanocatalysts. Here we report an experimental and theoretical study of the Ni particle size effect on activity of steam methane reforming (SMR) to achieve a better understanding of the size dependence of kinetic behavior at an atomic level. A kinetic study illustrated the higher forward methane turnover frequency on the smaller sized Ni particles. The size-dependent activity was well reproduced by microkinetic modeling on a truncated octahedron model with the kinetic parameters estimated by the improved unity bond index-quadratic exponential potential (UBI-QEP) and the Brønsted–Evans–Polanyi (BEP) relationship. Microkinetic modeling suggested that the size-dependent activity of Ni catalysts is associated with the surface-dependent activity. Much higher activity of Ni(2 1 1) than Ni(1 1 1) and Ni(1 0 0) accompanied by decreased Ni(2 1 1) surface fraction results in reduced Ni activity as particle size increases. The activity of Ni(1 1 1) is limited by high free energy barriers, while that of Ni(1 0 0) is limited by site blockage by C* and CH*. This work offers a feasible approach to gain insight into size-dependent activity and to aid rational catalyst design for SMR in which preparing extremely small Ni particles (≤6 nm) might be a good strategy. [ABSTRACT FROM AUTHOR]

• A series of Zn SACs synthesized via a ZIF-8-mediated sacrificial template strategy. • Zn–N–C–T exhibited high performance in transfer hydrogenation nitrobenzene to aniline. • The activity of Zn–N–C–T is closely related to the coordination number of Zn sites. • The hydrogenation mechanism over Zn–N–C–1223 is disclosed by the DFT calculations. Metal single-atom catalysts (SACs) have great potential to replace traditional nanoparticle catalysts in practical applications, however, the task-specific construction of SACs containing metal–nitrogen (M−N) moiety with tunable M−N coordination number remains a colossal challenging issue. Herein, we report a facile strategy to modulate the s-band of Zn by constructing N-coordinated Zn SACs (denoted as Zn–N–C–T, T stands for the pyrolysis temperature) with tunable nitrogen coordination number (denoted as Zn–N x , x = 2, 3, and 4) and Zn loadings (ranging from 0.8 to 6.8% by weight) via a metal–organic framework-mediated pyrolysis method. The catalytic activity of Zn–N–C–T is found to be closely related to the coordination number of Zn single atomic sites for the transfer hydrogenation of nitroarene to arylamine, using hydrazine hydrate as a hydrogen source under environmental benign conditions, among which the under-coordinated Zn–N 3 with defect and asymmetric electron distribution in Zn–N–C–1223 exhibits the best catalytic activity, followed by lower-coordinated Zn–N 2 with defect in Zn–N–C–1273 and saturated coordination Zn–N 4 in Zn–N–C–1123. Experimental results and theoretical analysis uncover that appropriately lowering the coordination number increases the electron density of Zn single atoms and simultaneously introduces H-acceptor sites, which cooperatively contribute to the enhancement of the performance for transfer hydrogenation. [ABSTRACT FROM AUTHOR]

The finding that the MG selectivity increases and the DMO hydrogenation activity decreases with increasing the Ag nanoparticle size reveals the structure sensitivity of DMO partial hydrogenation. [Display omitted] • The structural sensitivity of DMO partial hydrogenation over Ag catalysts. • Ag stepped surfaces dominate the kinetics of the hydrogenation reaction. • The DMO consumption rate decreases with increasing the nanoparticle size. • The MG selectivity rises as the particle size changes from 5 nm to 10 nm. • A new strategy to ensure thermodynamic consistency of the reaction. Silver nanoparticles of different sizes have been synthesized to study their catalytic performance in dimethyl oxalate (DMO) partial hydrogenation to methyl glycolate (MG). Then, a detailed microkinetic analysis based on the results of DFT calculations has been performed to elucidate the origin of the observed size-dependent kinetics, where tabulated thermodynamic properties of gas-phase species are used to ensure the thermodynamic consistency of the reaction. Calculated results show that the turnover frequency for DMO consumption is much higher on Ag(2 1 1) than on Ag(1 1 1), suggesting the stepped surface dominates the kinetics. The hydrogenation of DMO on the two surfaces occurs along the same dominant reaction pathway, and the rate-determining step for the partial and deep hydrogenation of DMO is DMO and MG dissociation, respectively. The finding that the MG selectivity increases while the DMO hydrogenation activity decreases with the Ag nanoparticle size reveals the structure sensitivity of DMO partial hydrogenation. [ABSTRACT FROM AUTHOR]

Abstract: A novel approach to synthesize platelet carbon nanofibers (PCNFs) is proposed by taking advantage of the flat interfaces between Fe nanoparticles and flake supports. PCNFs are produced when Fe nanoparticles are supported on flakes of mica, SiO2 and graphite, and only fishbone carbon nanofibers (FCNFs) are obtained when γ-Al2O3 is used as a support. The crystalline perfection of PCNFs is found to depend on the dispersion of the catalyst and the surface roughness of the support. Perfect PCNFs are obtained when mica, which has a high surface tension and a very flat surface, is used as a support. The yield of PCNFs changes little with the nature of the support but is strongly related to the size of Fe nanoparticles and the preparation method of the Fe catalysts. [Copyright &y& Elsevier]

Abstract: The paper reports an application of CO stripping-voltammetry as a diagnostic tool for the determination of surface composition of various PtRu nanoparticles (NPs). A series of electrochemical experiments on different systems, including monometallic Pt and Ru, a commercially available PtRu alloy, Ru@Pt (Ru NPs covered by a Pt shell), and their physical mixtures verified that the surface of the Ru@Pt particles does not contain significant amounts of ruthenium. A large cathodic shift (200mV) of the main CO stripping peak of the Ru@Pt with respect to that of Pt was observed, consistent with what has been found at other catalysts with a Pt skin but of a different architecture. An additional small separate stripping peak at a potential corresponding to the oxidation of adsorbed CO at Pt/C is interpreted as being due to either separate Pt particles in the catalyst or thick Pt shells at a minor fraction of the Ru@Pt particles. Since the method probes the whole sample it will be useful for assessment of catalyst homogeneity. [Copyright &y& Elsevier]

Abstract: Fe nanoparticles on the top of carbon nanofibers (CNFs) were synthesized by catalytic CVD on a purpose as catalysts for ammonia decomposition. The size and shape of Fe particles on the top of CNFs depended on the Fe particle reconstruction and CNF morphology. On a mica support Fe catalyst, platelet structure of CNFs was obtained with small, uniform, and unwrapped Fe particles on the top. HRTEM illustrated that the Fe particle surface is covered by a few graphene layers, which redissolves into the Fe particle and does not prevent the access of NH3 to active surface sites at reaction conditions. The catalyst is highly active and stable because the Fe particles are highly dispersed and physically isolated by CNFs, and the surfaces are largely exposed to the reactants. [ABSTRACT FROM AUTHOR]