Area-selective atomic layer deposition (AS-ALD) is attracting increasing interest because of its ability to enable both continued dimensional scaling and accurate pattern placement for next-generation nanoelectronics. Here we report a strategy for depositing material onto three-dimensional (3D) nanostructures with topographic selectivity using an ALD process with the aid of an ultrathin hydrophobic surface layer. Using ion implantation of fluorocarbons (CFx), a hydrophobic interfacial layer is formed, which in turn causes significant retardation of nucleation during ALD. We demonstrate the process for Pt ALD on both blanket and 2D patterned substrates. We extend the process to 3D structures, demonstrating that this method can achieve selective anisotropic deposition, selectively inhibiting Pt deposition on deactivated horizontal regions while ensuring that only vertical surfaces are decorated during ALD. The efficacy of the approach for metal oxide ALD also shows promise, though further optimization of the implantation conditions is required. The present work advances practical applications that require area-selective coating of surfaces in a variety of 3D nanostructures according to their topographical orientation.

Area-selective atomic layer deposition (ALD) is envisioned to play a key role in next-generation semiconductor processing and can also provide new opportunities in the field of catalysis. In this work, we developed an approach for the area-selective deposition of metal oxides on noble metals. Using O2 gas as co-reactant, area-selective ALD has been achieved by relying on the catalytic dissociation of the oxygen molecules on the noble metal surface, while no deposition takes place on inert surfaces that do not dissociate oxygen (i.e., SiO2, Al2O3, Au). The process is demonstrated for selective deposition of iron oxide and nickel oxide on platinum and iridium substrates. Characterization by in situ spectroscopic ellipsometry, transmission electron microscopy, scanning Auger electron spectroscopy, and X-ray photoelectron spectroscopy confirms a very high degree of selectivity, with a constant ALD growth rate on the catalytic metal substrates and no deposition on inert substrates, even after 300 ALD cycles. We demonstrate the area-selective ALD approach on planar and patterned substrates and use it to prepare Pt/Fe2O3 core/shell nanoparticles. Finally, the approach is proposed to be extendable beyond the materials presented here, specifically to other metal oxide ALD processes for which the precursor requires a strong oxidizing agent for growth.

A new generation of catalysts is needed to meet society's energy and resource requirements. Current catalyst synthesis does not fully achieve optimum control of composition, size, and structure. Atomic layer deposition (ALD) is an emerging technique that allows for synthesis of highly controlled catalysts in the form of films, nanoparticles, and single sites. The addition of ALD coatings can also be used to introduce promoters and improve the stability of traditional catalysts. Evolving research shows promise for applying ALD to understand catalytically active sites and create next-generation catalysts using advanced 3D nanostructures.

Rhodium (Rh) catalysts are among the major candidates for syngas conversion to higher oxygenates (C2+oxy), with manganese (Mn) as a commonly used promoter for enhancing the activity and selectivity toward C2+oxy. In this study, we use atomic layer deposition (ALD) to controllably modify Rh catalysts with MnO, by depositing manganese oxide as a support layer or an overlayer, in order to identify the function of the Mn promoter. We also compare the ALD-modified catalysts with those prepared by coimpregnation. An ultrathin MnO support layer shows the most effective enhancement for C2+oxy production. Transmission electron microscopy, temperature-programmed reduction, and diffuse reflectance infrared Fourier transform spectroscopy characterization indicates that formation of Rh–MnO interface sites is responsible for the observed activity and selectivity improvements, while ruling out Rh nanoparticle size and alloy or mixed oxide formation as significant contributors. MnO overlayers on Rh appear to suffer from poor stability upon CO adsorption and are less effective than a MnO support layer. Density functional theory (DFT) calculations show that MnO species on the Rh(111) surface lower the transition state energy for CO bond dissociation and stabilize the key transition state for C2+oxy synthesis more significantly than that for methane synthesis, leading to enhanced activity and C2+oxy selectivity.

Methanol is a major fuel and chemical feedstock currently produced from syngas, a CO/CO /H mixture. Herein we identify formate binding strength as a key parameter limiting the activity and stability of known catalysts for methanol synthesis in the presence of CO . We present a molybdenum phosphide catalyst for CO and CO reduction to methanol, which through a weaker interaction with formate, can improve the activity and stability of methanol synthesis catalysts in a wide range of CO/CO /H feeds.

This paper reports the synthesis of 2.5 nm gold clusters on the oxygen free and chemically labile support carbon nitride (C 3 N 4 ). Despite having small particle sizes and high enough water partial pressure these Au/C 3 N 4 catalysts are inactive for the gas phase and liquid phase oxidation of carbon monoxide. The reason for the lack of activity is attributed to the lack of surface −OH groups on the C 3 N 4 . These OH groups are argued to be responsible for the activation of CO in the oxidation of CO. The importance of basic −OH groups explains the well documented dependence of support isoelectric point versus catalytic activity.

In situ characterization of catalysts gives direct insight into the working state of the material. Here, the design and performance characteristics of a universal in situ synchrotron-compatible X-ray diffraction cell capable of operation at high temperature and high pressure, 1373 K, and 35 bar, respectively, are reported. Its performance is demonstrated by characterizing a cobalt-based catalyst used in a prototypical high-pressure catalytic reaction, the Fischer-Tropsch synthesis, using X-ray diffraction. Cobalt nanoparticles supported on silica were studied in situ during Fischer-Tropsch catalysis using syngas, H 2 and CO, at 723 K and 20 bar. Post reaction, the Co nanoparticles were carburized at elevated pressure, demonstrating an increased rate of carburization compared with atmospheric studies.

Nickel–iron oxyhydroxide (Ni–Fe–OOH) catalysts have been widely studied for their high activity for the oxygen evolution reaction (OER). Here we demonstrate improved OER activity through incorporation of a third cation, aluminum. Atomic layer deposition (ALD) was used to deposit thin films of nickel oxide (Ni–O) and nickel–aluminum oxide (Ni–Al–O) to measure activity for the OER. Electrochemical preconditioning of the oxide films led to the formation of the OER-active oxyhydroxide catalysts. For Ni–Al–O films, electrochemical preconditioning resulted in aluminum dissolution until a stable composition at a Ni:Al ratio of 9:1 was reached. Because iron can be incorporated into the films from the solution, compositional effects of iron were studied by controlling the iron impurity level in the electrolyte. Turnover frequencies (TOFs) were determined for each catalyst, and it was found that the highest performing electrocatalysts were the films containing nickel, aluminum, and iron, confirming that aluminum exerts a promotion effect on nickel oxyhydroxide catalysts. Studies showed that unlike the Ni–Fe–OOH films, for which the TOF had very little thickness dependence, the activity of Ni–Al–Fe–OOH catalysts was dependent on thickness. This effect may arise from morphological changes in the catalyst film that modulate the density of the active site with thickness. For the thinnest films, aluminum doping improved the TOF of Ni–Fe–OOH catalysts by over 3-fold.