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Magnetron sputtering is a versatile method for investigating model system catalysts thanks to its simplicity, reproducibility, and chemical-free synthesis process. It has recently emerged as a promising technique for synthesizing δ-Ni 5 Ga 3 thin films. Physically deposited thin films have significant potential to clarify certain aspects of catalysts by eliminating parameters such as particle size dependence, metal-support interactions, and the presence of surface ligands. In this work, we demonstrate the potential of magnetron sputtering for the synthesis and analysis of thin film catalysts, using Ni 5 Ga 3 as a model system. Initially, deposition conditions were optimized by varying the deposition pressure, followed by an investigation of the temperature effects, aiming to map a structure zone dependence on temperature and pressure as in the Thornton model. The evolution of film crystallinity was monitored using a combination of grazing incidence X-ray diffraction (GI-XRD) and high-resolution scanning electron microscopy (HR-SEM). Additionally, ultrathin films were synthesized and annealed in H 2 at high temperatures to demonstrate the possibility of producing size-controlled nanoparticles by adjusting the annealing conditions. This work demonstrates the full potential of magnetron sputtering as a technique for synthesizing model system catalysts in various forms, opening new avenues for the research and development of additional catalytic systems., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

While model studies with small nanoparticles offer a bridge between applied experiments and theoretical calculations, the intricacies of working with well-defined nanoparticles in electrochemistry pose challenges for experimental researchers. This perspective dives into nanoparticle electrochemistry, provides experimental insights to uncover their intrinsic catalytic activity and draws conclusions about the effects of altering their size, composition, or loading. Our goal is to help uncover unexpected contamination sources and establish a robust experimental methodology, which eliminates external parameters that can overshadow the intrinsic activity of the nanoparticles. Additionally, we explore the experimental difficulties that can be encountered, such as stability issues, and offer strategies to mitigate their impact. From support preparation to electrocatalytic tests, we guide the reader through the entire process, shedding light on potential challenges and crucial experimental details when working with these complex systems.

Colloidal synthesis is an excellent tool for the study of cooperative effects in nanoalloys. In this work, bimetallic CuNi nanoparticles of defined size and composition are fully characterized and tested for the oxygen evolution reaction. Copper addition to nickel leads to modifications in the structural and electronic properties, showing a higher concentration of surface oxygen defects and formation of active Ni 3+ sites under reaction conditions. The ratio O V /O L between oxygen vacancies and lattice oxygen shows a clear correlation with the overpotential, being an excellent descriptor of the electrocatalytic activity. This is attributed to modifications in the crystalline structure, leading to lattice strain and grain size effects. Bimetallic Cu 50 Ni 50 NP showed the lowest overpotential (318 mV vs RHE), low Tafel slope (63.9 mV dec -1 ), and excellent stability. This work unravels the relative concentration between oxygen defects and lattice oxygen (O V /O L ) as an excellent descriptor of the catalytic activity of bimetallic precatalysts., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A facile and rational approach to synthesize bimetallic heterogeneous tandem catalysts is presented. Using core-shell structures, it is possible to create spatially controlled ensembles of different nanoparticles and investigate coupled chemocatalytic reactions. The CO 2 hydrogenation to methane and light olefins was tested, achieving a tandem process successfully., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The Ni II literature complex cis -[Ni(C 6 F 5 ) 2 (THF) 2 ] is a synthon of cis -Ni(C 6 F 5 ) 2 that allows us to establish a protocol to measure and compare the ligand effect on the Ni II → Ni 0 reductive elimination step (coupling), often critical in catalytic processes. Several ligands of different types were submitted to this Ni-meter comparison: bipyridines, chelating diphosphines, monodentate phosphines, PR 2 (biaryl) phosphines, and PEWO ligands (phosphines with one potentially chelate electron-withdrawing olefin). Extremely different C 6 F 5 -C 6 F 5 coupling rates, ranging from totally inactive (producing stable complexes at room temperature) to those inducing almost instantaneous coupling at 25 °C, were found for the different ligands tested. The PR 2 (biaryl) ligands, very efficient for coupling in Pd, are slow and inefficient in Ni, and the reason for this difference is examined. In contrast, PEWO type ligands are amazingly efficient and provide the lowest coupling barriers ever observed for Ni II complexes; they yield up to 96% C 6 F 5 -C 6 F 5 coupling in 5 min at 25 °C (the rest is C 6 F 5 H) and 100% coupling with no hydrolysis in 8 h at -22 to -53 °C.

A Pd complex, cis-[Pd(C 6 F 5 ) 2 (THF) 2 ] (1), is proposed as a useful touchstone for direct and simple experimental measurement of the relative ability of ancillary ligands to induce C-C coupling. Interestingly, 1 is also a good alternative to other precatalysts used to produce Pd 0 L. Complex 1 ranks the coupling ability of some popular ligands in the order P t Bu 3 >o-TolPEWO-F≈tBuXPhos>P(C 6 F 5 ) 3 ≈PhPEWO-F>P(o-Tol) 3 ≈THF≈tBuBrettPhos≫Xantphos≈PhPEWO-H≫PPh 3 according to their initial coupling rates, whereas their efficiency, depending on competitive hydrolysis, is ranked tBuXPhos≈P t Bu 3 ≈o-TolPEWO-F>PhPEWO-F>P(C 6 F 5 ) 3 ≫tBuBrettPhos>THF≈P(o-Tol) 3 >Xantphos>PhPEWO-H≫PPh 3 . This "meter" also detects some other possible virtues or complications of ligands such as tBuXPhos or tBuBrettPhos., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)