In this work, bimetallic PdAg nanoparticles supported on oxidized Vulcan XC-72R carbon (O-Vulcan) were synthesized via a pulsed microwave-assisted polyol method and evaluated for the electrooxidation of glycerol in alkaline media. The PdAg catalysts exhibited a homogeneous nanoparticle dispersion (ca. 6 nm) and evident alloy formation, as confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) analysis revealed a negative shift in the Pd 3d binding energy, indicating electronic charge transfer from Ag to Pd. Among the as-prepared materials, PdAg10/C delivered the highest electrocatalytic performance, achieving a peak mass activity of 3 973mAmg-1 at 30 degrees C, which is 2.1 times higher than that of Pd/C, along with an onset potential shift of 90 mV, and improved tolerance to poisoning of 61.6% during cycling. The enhanced performance correlates with the increased electroactive surface area, the electronic modification of Pd evidenced by XPS, and alloy-induced lattice expansion observed by XRD, consistent with a synergistic electronic and bifunctional effect. Compared with previously reported PdAg systems, the present catalysts achieve superior activity using low Ag content and a rapid microwave-assisted synthesis route. These results demonstrate the potential of PdAg/C catalysts as efficient anodes for alkaline electrochemical energy conversion.

In this work, mandarin peel-derived biocarbons synthesized by fast pyrolysis are tested as support materials for PtPd nanoparticles for the electrochemical oxidation of glycerol in an alkaline electrolyte. The biocarbons, synthesized at 300 °C (mandarin peel-derived biocarbons (BCM)-300) and 500 °C (BCM-500), present good electronic conductivities and adequate surface properties. Bimetallic PtPd nanoparticles with average sizes between 3.5 and 3.9 nm and a Pt:Pd ratio of 3:1 are deposited over the biocarbons by a pulse microwave-assisted polyol method. The electrochemical experiments show that the mass-specific activity for the glycerol oxidation reaction of the PtPd particles supported over the biocarbons is higher than that reported for the bimetallic catalyst deposited over Vulcan carbon black. In addition, the catalyst deposited over the biocarbons presents lower potential onsets, lower apparent activation energies, and lower charge transfer resistances compared to the bimetallic particles supported over the commercial carbon material. The superior electrocatalytic performance of PtPd/BCM-300 and PtPd/BCM-500 catalysts is attributed to the synergistic effect between the bimetallic particles and the biocarbons, which promotes glycerol oxidation through both the electronic effects and the bifunctional mechanism.

In this work, a series of Pt-CuO(x)/C materials with different metal oxide contents were evaluated as electrocatalysts for the glycerol oxidation reaction (GOR) in an alkaline medium. CuO nanoparticles of ca. 6 nm were prepared by a precipitation/calcination route and incorporated into the carbon support with a weight percentage from 0 to 30. Platinum nanoparticles of ca. 3 nm were deposited over the different hybrid CuO(x)/C materials via the ethylene glycol reduction under pulsed microwave heating conditions. The electrochemical experiments showed that the onset potential for the GOR on the bimetallic Pt-CuO(x)/C electrodes is shifted negatively by ca. 160 mV, and the charge transfer resistance is significantly reduced compared to Pt/C, indicating that CuO facilitates both the electron charge transfer kinetics and the oxidation of the adsorbed intermediates. The most active electrode material, Pt-CuO(30)/C (30 wt % CuO on carbon), developed 3.5 times higher activity than Pt/C. This bimetallic electrode retained more than 90% of its initial activity after an accelerated cycling test.

Herein, Pt and Pt0.85Cu0.15 nanoparticles were deposited over hybrid CuO/C supports (1.5, 3 and 5 wt.% on carbon) by a pulsed microwave-assisted reduction method and the as-prepared materials were evaluated as electrocatalysts toward the electrooxidation of glycerol in alkaline medium. The structural and morphological analysis showed that the platinum particles decrease from 4.2 nm to around 3.0 nm in size when the CuO crystallites are present on the surface of the carbonaceous material. The electrochemical experiments indicated that the nanoparticles deposited over the hybrid support present significantly improved electrocatalytic prop-erties compared to Pt/C. Among them, Pt0.85Cu0.15 CuO(3)/C catalyst exhibited the best performance for the GOR, delivering a mass activity of around 270 mA mg(Pt)(-1) at a fixed potential of 0.7 V, which is 5.4 times higher than that of Pt/C (similar to 50 mA mg(Pt)(-1)). The results showed that the addition of very small amounts of copper oxide on the surface of the carbonaceous support and the addition of a small amount of Cu to Pt boost the activity of the active sites via the bifunctional mechanism, geometric strain and ligand effects.

This work investigates the electrooxidation of glycerol in an alkaline environment at non-doped and P-doped Pt-alpha Ni(OH)(2) nanoparticles supported on oxidized Vulcan XC-72R carbon. Pt-alpha Ni(OH), and PtP-alpha Ni(OH)(2) particles with sizes in the range of 3-5 nm were obtained via a one-step chemical reduction approach. The physicochemical characteristics of the as-prepared catalysts were studied by inductively coupled plasmaoptical emission spectrometry (ICP-OES), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x-ray diffraction (XRD) techniques. It was determined that the incorporation of phosphorus lead to the formation of amorphous PtP-alpha Ni(OH)(2) deposits. TEM analysis showed that the incorporation of phosphorus into the bimetallic Pt-alpha Ni(OH)(2 )catalyst origins a remarkable reduction in the average size of the nanoparticles with a narrow size distribution. A substantial improvement in the electrocatalytic properties of the Pt-alpha Ni(OH)(2) system toward the oxidation of glycerol was observed through P doping. The P-doped electro-catalysts developed a mass current density of 60.3 mA mg(pt)(-)(1) at 765 mV vs. RHE, which is about 5 and 45 times higher than those of commercial PtRu/C (12.3 mA mg(pt)(-1)) and as-synthesized Pt-alpha Ni(OH)(2)/C (1.5 mA mg(pt)(-1)), respectively. The temperature-dependent experiments displayed that the apparent activation energy for the reaction is halved upon the addition of phosphorus.

In this work, the influence of Cu-doping on the ability of NiO co-catalyst to enhance the electrocatalytic properties of carbon-supported Pt nanoparticles toward ethanol and glycerol oxidation was investigated. The Cu-doped NiO particles were synthesized by a precipitation method, while the noble metal nano-particles were deposited over the hybrid Cu-doped NiO/C supports via a pulsed microwave-assisted polyol method using ethylene glycol as reductant. Pt-NiO and Pt-NiOCuO(x:y)/C catalysts with Ni:Cu atomic ratios of 9:1 (Pt-NiOCuO(9:1)/C), 7:3 (Pt-NiOCuO(7:3)/C) and 5:5 (Pt-NiOCuO(5:5)/C) were obtained. The physicochemical analysis showed that the as-prepared catalysts are composed of nanoparticles of about 3 nm. The potentiostatic experiments exhibited that the Pt-NiOCuO( 7:3)/C catalyst is the most active catalyst for ethanol oxidation, while the Pt-NiOCuO(5:5)/C catalyst exhibited the best performance for glycerol oxidation. These catalysts developed mass current densities of almost 12 and 5 times higher than those of bare Pt/C for ethanol and glycerol oxidation reactions, respectively. Moreover, an accelerated multicycling stability test displayed that the as-prepared catalysts retain almost 98% of their initial mass current density. (c) 2022 Published by Elsevier B.V.

Pinus pinea produces the most expensive pine nuts worldwide, with a masting habit (variable cone productivity over time) in its native habitat. This study assessed the presence of masting habit in a non-native area, the correlation of annual cone production with climatic variables, and the impact of resource depletion on cone productivity 3 and 4 years after a bumper crop. During 10 years, all cones tree−1 were harvested and counted in three plantations. Cone yield stability was measured via coefficient of variation of cones tree−1. Climatic factors were correlated with stone pine masting. Results indicated that inter-annual variability of cone yield and annual rainfall during 3 years prior to seed maturity, and thermal oscillation 2 years before harvest, were significantly correlated. A correlation was found between cone productivity when reproductive shoot differentiation or when male and female primordia induction occurred, and cone productivity 3 and 4 years later. Individual tree fruit load did not reduce flower induction. The most productive trees will also be the most productive ones in the following years, a finding with practical implications for breeding programs and plant production.

Four carbon supported trimetallic PtNiCu nanostructured catalysts have been successfully synthesized by a two-step chemical/electrochemical reduction route. Nanoparticles with average sizes in the range of 2.2-3.5 nm with mixed alloy, pseudo core-shell and core-shell patterns were obtained. All as-prepared electrocatalysts exhibited high electroactive surface areas, ranging from 93 to 117 m(2) g(-1). The electrocatalytic activity of the trimetallic materials towards the ethanol oxidation reaction (EOR) was studied by cyclic voltammetry and chronoamperometry at temperatures between 20 and 60 degrees C. Among the studied catalysts, the alloy nanomaterial with a Pt:Cu:Ni surface atomic ratio of 36.8:57.0:6.2 and the pseudo core-shell material with a Pt:Cu:Ni surface atomic ratio of 18.0:43.6:38.4 exhibited the best performance for the EOR. These nanostructured catalysts presented lower onset potentials, four times higher mass activities, and 8-10 times higher specific activities than a commercial PtRu/C catalyst. The kinetic parameters (i.e., Tafel slope and apparent activation energy) indicated that the electro-oxidation of ethanol on the as-prepared catalysts was faster than on PtRu/C. (C) 2019 Elsevier Ltd. All rights reserved.

Stone pine ( Pinus pinea L.) was introduced to Argentina and Chile approximately a century ago for several uses, mainly for dune stabilization, but not for pine nut production. Many plantations were established along the Mediterranean coastal area of both countries, where some areas have unproductive soils. The comparison of growth and fruit quality on stone pine in exotic and native environments is useful to gain insights on the potential crop areas outside the species native habitat. Accordingly, we provided a comparison of growth performance (diameter at breast height and height) and pine nut chemical composition among stone pine populations cultivated along coastal areas in Argentina and Chile. Results showed similar growth rates between countries, with these values being higher than values reported for coastal areas of Italy and Spain (native habitat), where thermal oscillations are lower and average temperatures are higher. Pine nut composition analyses highlighted an elevated high-quality fat and protein content. We conclude that stone pine could be cultivated in coastal areas of the Southern hemisphere, where the species grows vigorously and its pine nuts maintain the worldwide reported beneficial properties. The study provides information for improving forestry management in the tested areas.

Bimetallic Pt-Ru particles supported on glassy carbon rods were synthesized by simultaneous electrochemical deposition. Pt-Ru alloy particles were deposited from a dilute aqueous acid solution of chloroplatinic acid and ruthenium trichloride by different electrochemical techniques: (i) coulostatic deposition at constant potential; (ii) double potentiostatic steps; and (iii) multiple cycles of potentiostatic pulses. It was found that particle size distribution, and the morphology and composition of the deposits strongly depend on the deposition method. Scanning electron microscopy images showed the presence of agglomerates with diameters in the submicrometre scale composed of nano-sized particles. The catalysts prepared by multiple cycles of potentiostatic pulses exhibited better activity for methanol oxidation and enhanced tolerance to CO poisoning compared with those prepared by the other techniques. This behaviour could be associated with the structure containing a high number of defects of the particles and a higher ruthenium content in the solid solution.

Four carbon supported PtCu nanostructured catalysts with Pt:Cu atomic ratios of 1:3.20, 1:2.23, 1:0.61 and 1:0.35 were synthesized by a two-step route, involving the chemical reduction of Cu ions on the carbon support, followed by the partial galvanic replacement of Cu atoms by Pt. Bimetallic nanostructured particles with average sizes in the range of 2.3 3.2 nm were obtained. The bimetallic catalysts with surface Pt contents between 20 and 55 at. % were formed by a Cu-rich core surrounded by a Pt-Cu shell, while that with the highest Pt content presented a uniform alloy structure instead of a core-shell arrangement. The electrocatalytic performance of the as-prepared materials toward ethanol electrooxidation in acid and alkaline media and glycerol oxidation in alkaline environment was investigated by cyclic voltammetry and chronoamperometry. It was observed that the electrocatalytic activity of PtCu nanoparticles was found to depend on the surface composition, platinum utilization efficiency, structure and Pt ensemble. Among the as prepared catalysts, Pt0.62Cu0.38/C core-shell material showed the best performance for ethanol oxidation in both acid and alkaline environments, while Pt0.24Cu0.7/C and Pt0.31Cu0.69/C core-shell catalysts exhibited the highest activity for glycerol oxidation in alkaline medium. The electrochemical results showed that the catalytic activity of the bimetallic Cu@PtCu core-shell nanostructured nanoparticles is between four and ten times higher than that of a commercial Pt0.51Ru0.49/C catalyst. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Cone to pine nut yield (PY), an important commercial feature of stone pine cropping, was higher in Chile than in main producer countries. PY is highly variable along years and depends on pine nut number inside cones, followed by pine nut weight. Cone morphometry is not a good indicator of PY, thus selecting cones for size/weight will not improve it.

In this work, we prepared four electrocatalysts based on trimetallic PtPdNi nanoparticles on different carbon supports, i. e., i) two activated carbons produced from biomass, ii) micro-mesoporous carbon synthesized by the nanocasting method, and iii) commercial carbon black. The electrocatalytic activity of the prepared materials was tested in the electro-oxidation of ethanol in alkaline medium. Well-distributed nanoparticles with sizes in the range of 3.5-5.2 nm were obtained through galvanic replacement. The bulk Pt, Pd and Ni contents were about 65, 25 and 15 at. %, measured by EDX and ICP-AES. By XPS the surface Pt : Pd atomic ratios were in the range of 1.82-2.2. Electrochemical experiments showed that the trimetallic nanoparticles deposited over micro-mesoporous carbon material exhibit the highest electrochemical activity towards ethanol electro-oxidation in alkaline medium. Results showed that both synthetic carbon and biomass-derived carbon are suitable materials to support electrocatalysts in low-temperature fuel cells.

The synthesis of unsupported Ni(Pt-Pd) catalysts via a two-step process under the assistance of a magnetic field in the presence and absence of sodium citrate was investigated. In absence of the complex agent, sandspur-like (Ni-SS(PtPd)) particles of about 90 nm with thorns of ca. 40 nm in length were obtained, while in the presence of citrate anion the catalyst showed the occurrence of nanowires (Ni-NW(PtPd)), with lengths in the range of 1-10 mu m formed by grains of about 45 nm in size. The catalysts prepared in-house were tested for ethanol electro-oxidation in alkaline medium at room temperature. The activity of Ni-NW(PtPd) electrode was almost 32% higher than that of Ni-SS(PtPd) material, while the poisoning rate was smaller at the same potential range. Hence, considering that both catalysts have practically the same composition, it is interesting to note that Ni-NW(PtPd), which has the smallest electroactive surface area, is the one that presents the highest activity for the ethanol oxidation reaction (EOR). This result could be attributed to the lattice strain and electronic effects derived from the particle structure and morphology of the particles, and the electron transport rate through the materials.

Few studies have been conducted on Stone pine (Pinus pinea) morphology, cone to kernel yield (KY) and composition. To study the species variability, a morphometric and chemical characterization of pine nuts was performed across the species distribution in Chile. Seventy-six highly productive trees were selected in three macrozones. Ten cones per tree were harvested, and cone weight, in-shell pine nut number cone(-1) and size and weight of in-shell pine nuts and kernels were measured; KY was determined. Chemical and nutritional characterization of pine nuts was performed in 38 trees. Differences among macrozones were tested with mixed linear models. Partial correlation was used to test for correlation between cone and pine nut morphometric data, chemical features, and climate. Canonical correlation coefficients between groups were tested. Selected trees differed in cone and in-shell pine nut size, kernel morphometry, and KY, with lowest trait values being generally found in the coast. KY was higher than in Europe. Chemical composition was similar to values reported in producer countries, homogeneous among macrozones, with the exception of oleic acid and potassium. Detected differences would respond to the environment and to the interaction genotypexenvironment given the restricted origins of the genetic material, confirming the species adaptability.

This work reports a non-enzymatic amperometric sensor for hydrogen peroxide based on the use of a glassy carbon composite electrode modified with core-shell Cu@PtPd/C nanoparticles. Cu@PtPd/C presents an important electrocatalytic activity towards hydrogen peroxide reduction. The comparison of the sensitivities and the charge transfer resistances for hydrogen peroxide at the glassy carbon composite electrode modified with 5.0% w/w PVC, Pd/C, Pd/C + Pt/C and Cu@PtPd/C demonstrate a clear synergism on the catalytic reduction of hydrogen peroxide at - 0.100 V when having Pt, Pd and Cu incorporated in the core-shell nanostructure. The best compromise between sensitivity, reproducibility and response time was reached with 20.0% w/w Cu@PtPd/C. For the selected sensor (glassy carbon composite electrode containing 20.0% w/w GCPE/Cu@PtPd/C) the analytical parameters are highly competitive compared to similar devices reported in the last years, with a linear relationship between current and hydrogen peroxide concentration between 5.0 x 10(-6) and 2.5 x 10(-4) M, sensitivity of (5.30 +/- 0.09) x 10(5) mu AM(-1) cm(-2) (r(2) = 0.998) and detection limit of (3.7 +/- 0.5) x 10(-7) M. The resulting sensing platform was successfully used for the quantification of hydrogen peroxide in a mouth-wash sample.

Highly porous Cu foams comprised of interconnected branched dendrites were used as sacrificial templates for the fabrication of pseudo core-shell Cu@Pt and Cu@Pt-Ru unsupported electrodes by galvanic replacement. The as-prepared materials presented a three-dimensional structure with pores between 17 and 45 mm made of superimposed layers of ramified dendrites. TEM analysis showed that the dendrites were composed of agglomerates of grains of about 4 nm in size and mesopores of ca. 30 nm in diameter. The as-prepared 3D electrodes were tested for methanol oxidation in acid media at different temperatures. The results showed that the catalytic activities of Cu@Pt and Cu@Pt-Ru foams normalized to the electrochemical surface area are almost 50% higher than that of a commercial Pt-Ru/C material, with poisoning rates that are reduced by half in the same potential range. The enhanced behavior of the as-prepared foams is believed to be the result of the influence of copper atoms on the reactivity of platinum sites, the highly defective structure of the electrodes, as well as the facilitated diffusion of methanol molecules and the products formed during the reaction throughout the highly porous three-dimensional structure of the electrode. The apparent activation energies (E-a,E-app) for the methanol oxidation reaction (MOR) were determined by potentiostatic experiments. E-a,E-app values of 29.07 and 24.20 kJ mol(-1) were calculated for Cu@Pt and Cu@Pt-Ru foams at 0.3 V, respectively. The results suggested that the MOR is governed by the dissociative adsorption of methanol as a result of the multifunctional nature of the catalyst and the facilitated diffusion of the products formed during the reaction.

This article describes the main strategies to activate and convert carbon dioxide (CO2 ) into valuable chemicals over catalytic surfaces. Coherent elements such as common intermediates are identified in the different strategies and concisely discussed based on the reactivity of CO2 with the aim to understand the decisive factors for selective and efficient CO2 conversion.

The recent advances in the development of heterogeneous catalysts and processes for the direct hydrogenation of CO2 to formate/formic acid, methanol, and dimethyl ether are thoroughly reviewed, with special emphasis on thermodynamics and catalyst design considerations. After introducing the main motivation for the development of such processes, we first summarize the most important aspects of CO2 capture and green routes to produce H2. Once the scene in terms of feedstocks is introduced, we carefully summarize the state of the art in the development of heterogeneous catalysts for these important hydrogenation reactions. Finally, in an attempt to give an order of magnitude regarding CO2 valorization, we critically assess economical aspects of the production of methanol and DME and outline future research and development directions.