Core–shell Pd–P@Pt–Ni nanoparticles with enhanced activity and durability as anode electrocatalyst for methanol oxidation reaction

The Pd–P@Pt–Ni core–shell nanoparticles consist of an amorphous core and a low-crystalline shell. They exhibit the excellent catalytic properties in MOR owing to the double synergistic effects from the core and the nickel species in the shell.

Aerobic Oxidation-Functionalization of the Aryl Moiety in van Koten’s Pincer Complex (NCN)Ni(II)Br: Relevance to Carbon-Heteroatom Coupling Reactions Promoted by High-Valent Nickel Species

The growing popularity of metal-promoted C-H functionalization methodologies has led to increased efforts aimed at improving our understanding of the mechanistic underpinnings of C-C or C-heteroatom bond forming steps. One...

Nano-Sized NiO Immobilized on Au/CNT for Benzyl Alcohol Oxidation: Influences of Hybrid Structure and Interface

Tiny gold nanoparticles were successfully anchored on carbon nanotubes (CNT) with NiO decoration by a two-step synthesis. Characterizations suggested that Ni species in an oxidative state preferred to be highly dispersed on CNT. During the synthesis, in situ reduction by NaBH4 and thermal treatment in oxidation atmosphere were consequently carried out, causing the formation of Au-Ni-Ox interfaces and bimetal hybrid structure depending on the Ni/Au atomic ratios. With an appropriate Ni/Au atomic ratio of 8:1, Ni atoms migrated into the sub-layers of Au particles and induced the lattice contraction of Au particles, whilst a higher Ni/Au atomic ratio led to the accumulation of NiO fractions surrounding Au particles. Both contributed to the well-defined Au-Ni-Ox interface and accelerated reaction rates. Nickel species acted as structure promoters with essential Au-Ni-Ox hybrid structure as well as the active oxygen supplier, accounting for the enhanced activity for benzyl alcohol oxidation. However, the over-layer of unsaturated gold sites easily occured under a high Ni/Au ratio, resulting in a lower reaction rate. With an Au/Ni atomic ratio of 8:1, the specific rate of AuNi8/CNT reached 185 μmol/g/s at only 50 °C in O2 at ordinary pressure.

Experimental Electrochemical Potentials of Nickel Complexes

Nickel-catalyzed cross-coupling and photoredox catalytic reactions has found widespread utilities in organic synthesis. Redox processes are key intermediate steps in many catalytic cycles. As a result, it is pertinent to measure and document the redox potentials of various nickel species as precatalysts, catalysts, and intermediates. The redox potentials of a transition-metal complex are governed by its oxidation state, ligand, and the solvent environment. This article tabulates experimentally measured redox potentials of nickel complexes supported on common ligands under various conditions. This review article serves as a versatile tool to help synthetic organic and organometallic chemists evaluate the feasibility and kinetics of redox events occurring at the nickel center, when designing catalytic reactions and preparing nickel complexes.1 Introduction1.1 Scope1.2 Measurement of Formal Redox Potentials1.3 Redox Potentials in Nonaqueous Solution2 Redox Potentials of Nickel Complexes2.1 Redox Potentials of (Phosphine)Ni Complexes2.2 Redox Potentials of (Nitrogen)Ni Complexes2.3 Redox Potentials of (NHC)Ni Complexes

Steam Reforming of Chloroform-Ethyl Acetate Mixture to Syngas over Ni-Cu Based Catalysts

NiCuMoLaAl mixed oxide catalysts are prepared and applied in the steam reforming of chloroform-ethyl acetate (CHCl3-EA) mixture to syngas in the present work. The pre-introduction of Cl- ions using chloride salts as modifiers aims to improve the chlorine poisoning resistance. Catalytic tests show that KCl modification is obviously advantageous to increase the catalytic life. The destruction of catalyst structure induced by in situ produced HCl and carbon deposits that occurred on acidic sites are two key points for deactivation of reforming catalysts. The presence of Cl− ions gives rise to the formation of an Ni-Cu alloy, which exhibits a synergetic effect on catalyzing reforming along with metallic Ni crystals formed from excess nickel species, and giving an excellent catalytic stability. Less CHCl3 and more steam can also increase the catalytic stable time of KCl-modified NiCuMoLaAl reforming catalyst.

Preparation and characterization of NiO/HY catalyst

NiO/HY catalyst was prepared by impregnation method with the nickel acetate as the precursor and the HY as the carrier. The influences of impregnation solution acidity, the nickel species and the calcination process on the catalyst structure were studied by the nitrogen physical adsorption and XRD. The hydrogenation reaction of dicyclopentadiene (DCPD) was selected to evaluate the catalytic performance of the prepared catalyst. Experiments showed that the structure of the catalyst is critical to its performance, and NiO/HY catalyst has a good application prospect.

Modulation of Metal Species as Early Control Point for Ni-catalyzed Stereodivergent Semihydrogenation of Alkynes with Water

A base-assisted metal species modulation mechanism enables Ni-catalyzed stereodivergent semihydrogenation of alkynes with water, delivering both olefinic isomers smoothly using cheap and nontoxic catalysts and additives. Different from most precedents, in which E-alkenes derive from the isomerization of Z-alkene products, the isomers were formed in orthogonal catalytic pathways. Mechanistic studies suggest base as a key early element in modulation of the reaction pathways: by adding different bases, nickel species with disparate valence states could be accessed to initiate two catalytic cycles toward different stereoisomers. The practicability of the method was showcased with nearly 70 examples, including internal and terminal triple bonds, enynes and diynes, affording semi-hydrogenated products in high yields and selectivity.

Quantification of Classified Nickel Species in Spent FFC Catalysts

The paper presents a quick method for the quantification of nickel species in spent FFC catalysts; the quantification of known quantities NiO and $$\hbox{NiAl}_2\hbox{O}_{4}$$ NiAl 2 O 4 is first done in a matrix of fresh zeolite Y, and then in a complex matrix, similar to the one of a real spent catalyst. The method is carefully checked and the errors in the quantification are critically evaluated. After the validation of the method with known quantities of NiO, well below the law limit for direct re-use, a set of real spent catalysts (representative of a period of 12 months) is analysed. Graphic Abstract