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Developing high‐performance, low‐loading, Ir‐based electrocatalysts for the oxygen evolution reaction (OER) in acidic media is still a great challenge. Herein, we fabricated an iridium manganese catalyst with only 5 % iridium. The influence of the manganese dioxide phase states (α‐, β‐, γ‐ and δ‐MnO2) on the OER performance of IrO2/MnO2 catalysts was investigated. α‐MnO2, as the substrate, can generate smaller iridium particles and more high‐valence‐state iridium to promote OER performance. Therefore, the 5 % IrO2/α‐MnO2 electrocatalyst exhibits excellent electrocatalytic OER performance with a high mass activity of 216.67 A/gIr and 655.33 A/gIr at 1.53 V in acidic and alkaline media, respectively, significantly outperforming commercial IrO2. [ABSTRACT FROM AUTHOR]

The influences of impurities and oxidation evolution of waste cooking oil on the preparation of bio‐jet fuel via hydroconversion were studied. The hydrogenation active sites and acid sites were covered by heavy metals, sulfides, and basic nitrogen compounds, resulting in the increase of selectivity for bio‐jet fuel by decreasing the selectivity of diesel, aromatics, and iso‐alkanes. The effects of impurities, oxidation on the reaction pathway, and product distribution became more distinct with higher catalyst acidity. The evolution and variation of naphthalene, indan, and phenanthrene obtained from cyclic fatty acids influenced the properties of fuel or evoked the catalyst deactivation. This work will help to design new catalysts for selective conversion of waste cooking oil into bio‐jet fuel. [ABSTRACT FROM AUTHOR]

Electrochemical valorization of non‐food biomass‐derived carboxylates into fuels is promising for the conversion, storage, and distribution of renewable electricity. Herein, we demonstrate that biofuels, hydrogen, and bicarbonate can be simultaneously produced in an electrochemical cell by one‐step electrolysis of free fatty acids under ambient conditions on 3D self‐supported ultralow Pt loading (2 wt %) electrode. The three valuable products can naturally separate from each other during the electrolysis in the alkaline aqueous solution. The experimental suggests that Pt(100) and Pt(110) are favorable for the production of non‐Kolbe and Kolbe hydrocarbons, respectively. DFT calculation further clarifies the adsorption and stabilization of the reaction intermediates on Pt(100) and Pt(110). [ABSTRACT FROM AUTHOR]

Fe‐doped transition metal (oxy)hydroxides are regarded as the most efficient oxygen evolution reaction (OER) electrocatalysts in alkaline conditions. The incorporation of Fe effectively enhances the OER activity of Co‐/Ni‐based materials, but the corresponding role of Fe in Co‐based (oxy)hydroxide materials still remains unresolved. Herein, α‐Co1−mFem(OH)x is synthesized and systematically engineered to study the effect of Fe content on the morphology, crystalline structure, electronic structure, and OER activity. As the Fe content is changed, the basic crystalline phase of α‐Co1−mFem(OH)x is consistent whereas the micromorphology changes. Much smaller and thinner nanoplates with more edge/defect sites are fabricated because of increased Fe incorporation. When the Fe content is more than 0.1, twin nanoparticles emerge at the edge/defect sites of the sister nanoplate. Additionally, the OER activity of α‐Co1−mFem(OH)x against Fe content can be plotted as a volcano curve. These data thus support a hypothesis that the edge/defect sites in α‐Co1−mFem(OH)x are responsible for the OER performance. The incorporation of Fe leads to not only the accelerated intrinsic reactivity of each active site, which is attributed to the strong electronic interaction between Co and Fe but also changes the number of edge/defect sites. [ABSTRACT FROM AUTHOR]

Abstract The aim of the study was to conduct comparative analyses on drying kinetics, color, rehydration ratio, polysaccharide content and aromatic components composition of shitake mushrooms dried by using hot air drying, infrared drying and intermittent microwave assisted hot air drying. Intermittent microwave–assisted drying resulted in greatly reduced drying time and higher drying rate in comparison with the other methods. The highest polysaccharide content (240.28 mg/100 g) was achieved when microwave–assisted drying was used. Furthermore, microwave–assisted drying showed its predominance in the categories and amount of generated nitric aroma (1.17%) during drying, and it could be a method for improving fresh–like characteristics of dried vegetables due to the moderate level of aldehydes (0.26%) and ketones (4.22%) formed during drying. Shitake mushrooms treated with hot air drying showed the greatest amount of sulfuric aromatic compounds (7.7%) and the highest rehydration ability as well as a lower total color difference in the cap. Therefore, shitake mushrooms dried by hot air or combined with microwave should be considered due to their enhanced physical properties or chemical components. Highlights • Microwave-assisted drying greatly improved the drying rate of shitake. • Microwave-assisted drying achieved the highest polysaccharide level. • Microwave-assisted drying achieved the highest nitric aromas level. • Hot air drying made the highest rehydration rate of dried shitake. • Hot air drying achieved the highest sulfuric aromas level. [ABSTRACT FROM AUTHOR]

Developing efficient electrocatalysts from the earth‐abundant transition‐metal family is a great challenge for overall water splitting. Herein, we developed an approach to regulate the morphology and electronic structure of α‐Co0.9Fe0.1(OH)x nanoplates, in which FeCl2 (as a precursor) plays a significant role under reflux conditions. The resulting 2D α‐Co0.9Fe0.1(OH)x nanoplates exhibit more accessible edge active sites and more high‐valence Co species to boost its intrinsic activity. Therefore, this electrocatalyst shows outstanding oxygen evolution reaction performance (with an overpotential of 225 mV at 10 mA cm−2 and a Tafel slope of 39 mV dec−1 and good stability) and excellent activity toward the hydrogen evolution reaction (with an overpotential of 122 mV at 10 mA cm−2) in 1M KOH solution. When employed as bifunctional electrocatalysts on both the anode and cathode for overall water splitting, α‐Co0.9Fe0.1(OH)x can afford 10 mA cm−2 at 1.62 V with long‐term stability. The one‐pot synthesis of 2D Fe‐doped transition‐metal hydroxide nanoplates enriched with abundant edge sites may provide a new strategy for fabricating efficient overall water splitting catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Direct methanol fuel cells are promising renewable energy devices for automobiles and portable electronic devices. The development of high effciency, poison tolerance, long‐term stability, and noble metal‐free electrocatalysts for methanol oxidation is still a major challenge. Herein, we develop a noble metal‐free, 3D self‐supported, defect‐rich, hierarchical shell‐core structured Ni3S2 composite on Ni foam as electrocatalyst. This electrocatalyst shows a good activity, poison tolerance, and long‐term durability towards methanol oxidation in alkaline media. It shows the lowest onset potential (−340 mV vs. Hg/HgO) among all the Ni‐based catalysts reported up to date and a Pt‐level specific activity. The methanol oxidation peak current of the electrocatalyst retains more than 97.5 % even after 5,000 voltammetry cycles in 0.5 M KOH+1 M CH3OH. The morphology and composition of the electrocatalysts before and after stability test were characterized by SEM, TEM, XRD, and XPS. The high activity, poison tolerance, and stability are attributed to the binder‐free, directly grown Ni3S2 shell on the Ni foam backbone, the lattice defect sites, and the synergetic effects between the in‐situ formed active NiOx core and Ni3S2 shell during methanol oxidation. This work indicates that the self‐supported hierarchical shell‐core Ni3S2@Ni foam electrocatalyst is a viable alternative for commercial Pt‐based electrocatalyst applied in fuel cells. [ABSTRACT FROM AUTHOR]

A nickel (Ni) nanoparticle catalyst, supported on 4‐channel α‐Al2O3 hollow fibers, was synthesized by atomic layer deposition (ALD). Highly dispersed Ni nanoparticles were successfully deposited on the outside surfaces and the inside porous structures of hollow fibers. The catalyst was employed to catalyze the dry reforming of methane (DRM) reaction and showed a methane reforming rate of 2040 Lh−1gNi−1 at 800°C. NiAl2O4 spinel was formed when Ni nanoparticles were deposited on alpha‐alumina substrates by ALD, which enhanced the Ni‐support interaction. Different cycles (two, five, and ten) of Al2O3 ALD films were applied on the Ni/hollow fiber catalysts to further improve the interaction between the Ni nanoparticles and the hollow fiber support. Both the catalyst activity and stability were improved with the deposition of Al2O3 ALD films. Among the Al2O3 ALD coated catalysts, the catalyst with five cycles of Al2O3 ALD showed the best performance. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2625–2631, 2018 [ABSTRACT FROM AUTHOR]

Abstract: Transition‐metal chalcogenides have been widely investigated as a class of promising oxygen evolution reaction (OER) catalysts. But, they are still far from practical use because of moderate catalytic activity. Two‐dimensional (2D) materials with porous nanostructures are attractive for the efficient conversion of electrochemical energy. Herein, Co1‐xS novel porous microplates were synthesized through a facile self‐templated strategy based on the Kirkendall effect. By taking advantages of porous nanostructure and good catalytic properties of the hexagonal Co(OH)2 template, the unique Co1‐xS microplates provide higher efficient surface area and more accessible active sites. Moreover, the mass transfer and gas diffusion are also promoted, owing to the pores developed inside the microplates. As expected, the optimized porous Co1‐xS microplates demonstrate remarkable OER performance in alkaline electrolyte with an overpotential of 311 mV at 10 mA cm−2, a Tafel slope of 55 mV dec−1 and long‐term stability, which outperform the commercial IrO2 catalyst. The facile preparation, high catalytic activity, and excellent durability of the Co1‐xS porous hexagonal microplates show great promise in energy conversion applications. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) plays a key role in energy conversion and storage processes such as water splitting and carbon dioxide reduction. However, the sluggish kinetics caused by insufficient active surface and limited charge transfer hinder OER's wide applications. In this work, a novel self-templating strategy for the fabrication of composite CoO-MoO2 nanocages with enhanced OER performance is proposed. By designing a nanocage structure and incorporating conductive MoO2 to promote both mass and charge transfer, high OER activity (η = 312 mV at 10 mA cm−2) as well as good stability in the resulting CoO-MoO2 composite nanostructure can be achieved. This versatile synthetic strategy can also be extended to other metals (such as W) to provide greater opportunities for the controlled fabrication of mixed metal oxide nanostructures for electrochemical applications. [ABSTRACT FROM AUTHOR]

A high-performance electrode for the electrocatalytic reduction of concentrated nitric acid is developed from an electrode based on carbon fiber paper supported Pt nanoparticles (nano-Pt/CFP). The nano-Pt/CFP electrode exhibits remarkable electrocatalytic reactivity at room temperature (488.6 mA mg − 1 for nanopolyhedral Pt, and 384.9 mA mg − 1 for nanothorn Pt) with a significant reduction in Pt usage compared with conventional Pt electrodes (0.0190 mA mg − 1 for Pt sheet or 0.3667 mA mg − 1 Pt mesh) and commercial Pt/C (288.5 mA mg − 1 ). The mechanism is discussed based on the electrochemical voltammograms and the composition of gaseous products, indicating a homogeneous autocatalysis process with NO and N 2 O as the main products. [ABSTRACT FROM AUTHOR]