Sulfination of Unactivated Allylic Alcohols via Sulfinate-Sulfone Rearrangement.

A dehydrative cross-coupling of unactivated allylic alcohols with sulfinic acids was achieved under catalyst-free conditions. This reaction proceeded via allyl sulfination and concomitant allyl sulfinate-sulfone rearrangement. Various allylic sulfones could be obtained in good to excellent yields with water as the only byproduct. This study expands the synthetic toolbox for constructing allylic sulfone molecules.

Ce4+/Ce3+ Redox Effect-Promoted CdS/CeO2 Heterojunction Photocatalyst for the Atom Economic Synthesis of Imines under Visible Light.

The employment of stoichiometric alcohols and amines for imine synthesis under mild and green reaction conditions is still a challenge in the field. In this work, based on our research foundation in the thermocatalytic synthesis of imines over ceria, a CdS/CeO2 heterojunction photocatalyst was constructed and successfully realized the atom-economic synthesis of imines under visible light without additives at room temperature. Mechanistic experiments and corresponding characterizations indicated that the CdS/CeO2 heterojunction can improve the separation efficiency of photogenerated carriers, which can be further enhanced by the Ce4+/Ce3+ redox pair by rapidly combining photogenerated e-. The in situ-reduced Ce3+ can better activate O2 to form Ce-O-O·, which, together with h+, efficiently accelerates alcohol oxidation, which is the rate-determined step for the synthesis of imines via oxidative coupling reaction of alcohol and amine. In addition, our photocatalyst exhibited fairly decent reusability and substrate universality. This work solves problems of using base additives and excess amine or alcohol in the reported photocatalytic systems and provides new insight for designing CeO2-based photocatalytic oxidation catalysts.

Construction of nickel sulfide phase-heterostructure for alkaline hydrogen evolution reaction.

Constructing transitionmetalsulfides (TMSs) heterostructure is an effective strategy to optimize the catalytic performance for hydrogen evolution reaction (HER) in alkaline medium. Herein, the rhombohedral nickel sulfide/hexagonal nickel sulfide (r-NiS/h-NiS) catalysts with the NiS phase-heterostructure were successfully fabricated by a simple one pot method. The r-NiS/h-NiS (1.25) (1.25 means the theoretical mole ratio of S and Ni added to reaction) displayed the excellent HER performance with low overpotential (101 ± 1 mV@10 mA cm-2) and small Tafel slope (62.10 ± 0.1 mV dec-1), which were superior to the pure phase r-NiS and h-NiS. In this work, the improved HER catalytic performances were attributed to the dense coupling interfaces between the r-NiS and h-NiS. This work shows the feasibility of construction NiS phase-heterostructure and provides a novel strategy for the application of NiS for water splitting.

Zr(OH)4 -Catalyzed Controllable Selective Oxidation of Anilines to Azoxybenzenes, Azobenzenes and Nitrosobenzenes.

The selective oxidation of aniline to metastable and valuable azoxybenzene, azobenzene or nitrosobenzene has important practical significance in organic synthesis. However, uncontrollable selectivity and laborious synthesis of the expensive required catalysts severely hinders the uptake of these reactions in industrial settings. Herein, we have pioneered the discovery of Zr(OH)4 as an efficient heterogeneous catalyst capable of the selective oxidation of aniline, using either peroxide or O2 as oxidant, to selectively obtain various azoxybenzenes, symmetric/unsymmetric azobenzenes, as well as nitrosobenzenes, by simply regulating the reaction solvent, without the need for additives. Mechanistic experiments and DFT calculations demonstrate that the activation of H2 O2 and O2 is primarily achieved by the bridging hydroxyl and terminal hydroxyl groups of Zr(OH)4 , respectively. The present work provides an economical and environmentally friendly strategy for the selective oxidation of aniline in industrial applications.

Coupling interface structure in NixS/Cu5FeS4 hybrid with enhanced electrocatalytic activity for alkaline hydrogen evolution reaction.

Bornite (Cu5FeS4) exhibits great potential for the alkaline hydrogen evolution reaction (HER) and few studies have been conducted on its electrocatalytic activity. Herein, we successfully fabricate NixS/Cu5FeS4 hybrid catalyst with interface structure between NixS nanoparticles (NPs) and Cu5FeS4 NPs. The NixS/Cu5FeS4 hybrid catalyst exhibits favorable HER performances in 1.0 M KOH electrolyte and demonstrates smaller overpotential and lower Tafel slope than bare NixS NPs and Cu5FeS4 NPs. The remarkable HER performances are attributed to the strongly coupling interface structure between NixS NPs and Cu5FeS4 NPs, which leads to synergistic effect optimizing the HER activity and enhancing the charge transfer during catalytic process. This work provides a promising strategy for the construction of Cu5FeS4-based hybrid catalyst and its application in energy systems.

Surfactant-free self-assembly to the synthesis of MoO3 nanoparticles on mesoporous SiO2 to form MoO3/SiO2 nanosphere networks with excellent oxidative desulfurization catalytic performance.

Recently, oxidative desulfurization (ODS) is favoured by researchers because it is based on mild conditions and does not consume hydrogen. However, the preparation process of catalyst for ODS was not green or costly, which limits its further industrial applications. In this study, a facile route has been explored to grow the mesoporous MoO3/SiO2 nanosphere networks (MoO3/SiO2 NN) using low-cost air without surfactants. Herein, the air not only served as the template to self-assemble and form the nanosphere network structure but acted as a mesopore-directing agent to make mesopores on the MoO3/SiO2 nanosphere. Moreover, the recovered waste mother liquor was also successfully applied to prepare nanomaterials. Gratifyingly, the nanocomposites of MoO3/SiO2 NN displayed remarkable pore structure, large specific surface area (201 m2  g-1) and excellent amphipathy (CA = 24.7° and 13.6° of water and n-octane, respectively) making it a promising catalyst for two-phase ODS reaction with H2O2 as an oxidant. Meanwhile, the high TOF value (56.6 h-1) and outstanding durability were obtained under optimum conditions (Yield > 99 % at 70 °C and O/S = 8:1 for 1 h, 20 mg catalyst) and the products were detected by GC-MS and 1H NMR. Therefore, an environmentally benign self-assembly procedure can facilely prepare more types of mesoporous catalysts for large-scale industrial application.

Hierarchical iron-doped CoP heterostructures self-assembled on copper foam as a bifunctional electrocatalyst for efficient overall water splitting.

A bifunctional electrocatalyst with peculiarly hierarchical snowflake-like iron-doped CoP heterostructures self-assembled on copper foam (CoFeP/CF) was synthesized via a facile hydrothermal-phosphidation pathway. The excellent electrochemical performance of CoFeP/CF can be attributed to the synergistic effect of cobalt and iron atoms, tuneful interaction between metal atoms and phosphorus, and the large electrochemical active surface area origined from its peculiarly hierarchical snowflake-like heterostructures with high surface roughness. With the small Tafel slope values (of 73.0 mV dec-1 for OER and 90.4 mV dec-1 for HER), CoFeP/CF demands the diminutive overpotentials (of 277.9 mV for OER and 152.6 mV for HER) to desire the current density of 50 mA cm-2 in alkaline electrolyte. Furthermore, CoFeP/CF exhibits outstanding electrochemical performance for the overall water splitting with the cell potential of 1.495 V to attain 10 mA cm-2 in a two-electrode cell.

CeO2 immobilized on magnetic core-shell microparticles for one-pot synthesis of imines from benzyl alcohols and anilines: Support effects for activity and stability.

Four types of core-shell materials with magnetic Fe3O4 microparticles as the core were prepared through different approaches using dopamine, glucose, tetrabutyl orthotitanate (TBOT), and tetraethyl orthosilicate (TEOS) as the shell precursor, respectively. CeO2 nanoparticles (NPs) was successfully immobilized onto these supports to fabricate efficient catalysts for the tandem catalytic synthesis of imines from benzyl alcohols and anilines at low temperature under air atmosphere. The as-prepared catalysts were detailedly characterized by TEM, EDX, XRD, FT-IR, XPS VSM, ICP, and CO2-TPD. Interestingly, these prepared catalysts showed higher catalytic activity than reported CeO2 catalysts. Most attractively, the catalyst with a shell ofnitrogen-doped-carbon derived from dopamine exhibited the best catalytic property, and outstanding stability and recyclability in the cycle experiment. According to the XPS and CO2-TPD characterization, the enhanced performance of Fe3O4@CN@CeO2 composites can be attributed to two reasons as follows: (1) the immobilization of CeO2 improved its alkalinity at low reaction temperature, and alkalinity is beneficial to promote the oxidation of alcohols to benzaldehyde, which is the rate-determining step for this tandem reaction; (2) the doped nitrogen generated Lewis basic site could satisfactorily stabilize Ce3+/Ce4+ pair of CeO2, which determined the catalytic activity and stability of CeO2 based catalysts for this tandem reaction. Moreover, the prepared catalysts could be facilely recovered from the reaction mixture with an external magnet. This work may provide a useful strategy for constructing CeO2 based catalysts for green and sustainable catalysis.

Ni modified Pd nanoparticles immobilized on hollow nitrogen doped carbon spheres for the simehydrogenation of phenylacetylene.

In this work, Ni modified Pd nanoparticles immobilized on hollow nitrogen doped carbon spheres were successfully prepared, denoted as Pd/Ni-N/C. The Pd/Ni-N/C showed a moderate catalytic activity for the catalytic reduction of 4-nitrophenol as a model reaction. When applied for the simehydrogenation of phenylacetylene, the Pd/Ni-N/C exhibited a much better catalytic performance than some other Pd-based catalysts. What's more, the selectivity of styrene could be kept at high levels even when the reaction time was prolonged. The superior catalytic performance may be ascribed to the incorporation of Ni and N species, which were detailedly characterized and contrastively demonstrated. The contained N groups could disperse and stabilize the supported metal nanoparticles. The Pd/Ni-N/C displayed no obvious decrease of catalytic activity and selectivity in the recycling tests, indicating the potential for various industrial applications.