Amorphous Sn/Crystalline SnS2 Nanosheets via In Situ Electrochemical Reduction Methodology for Highly Efficient Ambient N2 Fixation.

Electrochemical nitrogen reduction reaction (NRR) as a new strategy for synthesizing ammonia has attracted ever-growing attention, due to its renewability, flexibility, and sustainability. However, the lack of efficient electrocatalysts has hampered the development of such reactions. Herein, a series of amorphous Sn/crystalline SnS2 (Sn/SnS2 ) nanosheets by an L-cysteine-based hydrothermal process, followed by in situ electrochemical reduction, are synthesized. The amount of reduced amorphous Sn can be adjusted by selecting electrolytes with different pH values. The optimized Sn/SnS2 catalyst can achieve a high ammonia yield of 23.8 µg h-1 mg-1 , outperforming most reported noble-metal NRR electrocatalysts. According to the electrochemical tests, the conversion of SnS2 to an amorphous Sn phase leads to the substantial increase of its catalytic activity, while the amorphous Sn is identified as the active phase. These results provide a guideline for a rational design of low-cost and highly active Sn-based catalysts thus paving a wider path for NRR.

Pd-Co nanoalloys nested on CuO nanosheets for efficient electrocatalytic N2 reduction and room-temperature Suzuki-Miyaura coupling reaction.

Due to their synergistic and tunable effects, bimetallic alloy systems have recently attracted considerable attention as superior catalysts. Herein, Pd-Co bimetallic alloy nanoparticles were uniformly deposited onto CuO nanosheet supports. This nanostructured catalyst was first shown to be an effective catalyst to convert N2 to NH3 in 0.1 M KOH with a yield of 10.04 µg h-1 mg-1cat. and a faradaic efficiency of 2.16%. The catalyst also performed well in the Suzuki-Miyaura coupling reaction at room temperature without an inert atmosphere and any toxic solvents. Thus, the catalyst is consistent with the principles of green chemistry. Due to the synergistic effects, this bimetallic Pd-Co catalyst shows higher catalytic activity than its monometallic counterparts. Moreover, the Pd/Co ratio was tuned to achieve the best catalytic performance. Finally, the Pd-Co/CuO catalyst presented good stability and recyclability. The superior catalytic activity of the bimetallic alloy catalyst make it an alternative material for catalytic applications in the future.

Self-assembled three-dimensional Pd/MoS2/reduced graphene oxide nanocatalyst: A case for homogeneous leaching mechanism.

In this work, a new design of three-dimensional (3D) molybdenum disulfide -reduced graphene oxide nanosheets supported palladium (Pd/MoS2-rGO) catalyst was prepared by a facile one-pot self-assembled procedure. The existence of MoS2 not only succeeded in preventing the restacking of rGO nanosheets and increasing the specific surface area, but also afforded an additional transport platform for Pd nanoparticles to facilitate its catalytic properties. Because of the specific structural and different functional components, the as-prepared Pd/MoS2-rGO showed superior catalytic performance and reusability towards the cross-coupling reactions and the reduction of 4-nitrophenol. Moreover, it was confirmed that the catalytic nature of Pd catalyst is a kind of similar homogeneous leaching mechanism with the hot filtration test, the solid-phase poisoning and the three-phase test, etc. This means that leaching of soluble Pd species promotes the reaction process in the liquid phase, and the leaching Pd can return to the carrier of catalyst after completion of transformation. Therefore, the rational design of 3D MoS2-rGO hydrogel material supported highly active Pd nanoparticles, combined with a facile one-pot self-assembled procedure, provides a universal strategy to construct desirable 3D multifunctional nanocatalysts that can be used to research the catalytic nature of active Pd.

One-pot hydrothermal synthesis of magnetically recoverable palladium/reduced graphene oxide nanocomposites and its catalytic applications in cross-coupling reactions.

A facile, green, economical approach was designed to deposit palladium nanoparticles on magnetic reduced graphene oxide nanosheets (Pd-Fe3O4/rGO) via a one-pot hydrothermal synthesis method. The prepared Pd-Fe3O4/rGO nanocomposites were thoroughly characterized by Transmission electron microscopy, Scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. Importantly, the highly efficient catalytic property of the as-obtained Pd-Fe3O4/rGO catalyst was demonstrated for the Suzuki-Miyaura coupling reaction and Mizoroki-Heck coupling reaction. Significantly, the Suzuki-Miyaura coupling reactions could be efficiently performed in an environmentally friendly aqueous solution with no need for further additives. Besides, the nanocomposites could be conveniently separated from reaction system with an external permanent magnet for recycling and the inherent catalytic activity of the nanocomposites did not exacerbate after six repeated applications.