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1. Templated Growth of a Homochiral Thin Film Oxide

   https://doi.org/10.1021/acsnano.0c00398  

   Schilling, Alex C.; Therrien, Andrew J.; Hannagan, Ryan T.; Marcinkowski, Matthew D.; Kress, Paul L.; Patel, Dipna A.; Balema, Tedros A.; Larson, Amanda M.; Lucci, Felicia R.; Coughlin, Benjamin P.; et al (April 2020, ACS Nano)

   Chiral surfaces are of growing interest for enantioselective adsorption and reactions. While metal surfaces can be prepared with a wide range of chiral surface orientations, chiral oxide surface preparation is much more challenging. Herein, we demonstrate that the chirality of a metal surface can be used to direct the homochiral growth of a thin film chiral oxide. Specifically, we study the chiral ‘29’ copper oxide, formed by oxidizing a Cu(111) single crystal at 650 K. Surface structure spread single crystals which expose a continuous distribution of surface orientations as a function of position on the crystal, enabled us to systematically investigate the mechanism of chirality transfer between metal and oxide with high-resolution scanning tunneling microscopy. We discovered that the local underlying metal facet directs the orientation and chirality of the oxide overlayer. Importantly, single homochiral domains of the ‘29’ oxide were found in areas where the Cu step edges that templated growth were ≤20 nm apart. We used this information to select a Cu(239 241 246) oriented single crystal and demonstrate that a ‘29’ oxide surface can be grown in homochiral domains by templating from the subtle chirality of the underlying metal crystal. This work demonstrates how a small degree of chirality induced by very slight misorientation of a metal surface (~1 sites/ 20 nm2) can be amplified by oxidation to yield a homochiral oxide with a regular array of chiral oxide pores (~75 sites/ 20 nm2). This offers a general approach for making chiral oxide surfaces via oxidation of an appropriately miscut metal surface. 

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2. Giant Decrease in Interfacial Energy of Liquid Metals by Native Oxides

   https://doi.org/10.1002/adma.202406783  

   Jung, Woojin; Vong, Man Hou; Kwon, Kiyoon; Kim, Jong Uk; Kwon, S Joon; Kim, Tae‐il; Dickey, Michael D (November 2024, Advanced Materials)

   Abstract Native oxides form on the surface of many metals. Here, using gallium‐based liquid metal alloys, Johnson‐Kendall‐Roberts (JKR) measurements are employed to show that native oxide dramatically lower the tension of the metal interface from 724 to 10 mN m⁻¹. Like conventional surfactants, the oxide has asymmetry between the composition of its internal and external interfaces. Yet, in comparison to conventional surfactants, oxides are an order of magnitude more effective at lowering tension and do not need to be added externally to the liquid (i.e., oxides form naturally on metals). This surfactant‐like asymmetry explains the adhesion of oxide‐coated metals to surfaces. The resulting low interfacial energy between the metal and the interior of the oxide helps stabilize non‐spherical liquid metal structures. In addition, at small enough macroscopic contact angles, the finite tension of the liquid within the oxide can drive fluid instabilities that are useful for separating the oxide from the metal to form oxide‐encased bubbles or deposit thin oxide films (1–5 nm) on surfaces. Since oxides form on many metals, this work can have implications for a wide range of metals and metal oxides in addition to explaining the physical behavior of liquid metal. 

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3. Effects of Film Thickness of ALD-Deposited Al2O3, ZrO2 and HfO2 Nano-Layers on the Corrosion Resistance of Ti(N,O)-Coated Stainless Steel

   https://doi.org/10.3390/ma16052007  

   Dinu, Mihaela; Wang, Kaiying; Mouele, Emile S.; Parau, Anca C.; Vladescu; Liang, Xinhua; Braic, Viorel; Petrik, Leslie Felicia; Braic, Mariana (March 2023, Materials)

   The goal of this stydy was to explore the potential of the enhanced corrosion resistance of Ti(N,O) cathodic arc evaporation-coated 304L stainless steel using oxide nano-layers deposited by atomic layer deposition (ALD). In this study, we deposited Al2O3, ZrO2, and HfO2 nanolayers of two different thicknesses by ALD onto Ti(N,O)-coated 304L stainless steel surfaces. XRD, EDS, SEM, surface profilometry, and voltammetry investigations of the anticorrosion properties of the coated samples are reported. The amorphous oxide nanolayers homogeneously deposited on the sample surfaces exhibited lower roughness after corrosion attack compared to the Ti(N,O)-coated stainless steel. The best corrosion resistance was obtained for the thickest oxide layers. All samples coated with thicker oxide nanolayers augmented the corrosion resistance of the Ti(N,O)-coated stainless steel in a saline, acidic, and oxidising environment (0.9% NaCl + 6% H2O2, pH = 4), which is of interest for building corrosion-resistant housings for advanced oxidation systems such as cavitation and plasma-related electrochemical dielectric barrier discharge for breaking down persistent organic pollutants in water. 

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4. The coordination chemistry of oxide and nanocarbon materials

   https://doi.org/10.1039/D2DT00459C  

   Bekyarova, Elena; Conley, Matthew P. (June 2022, Dalton Transactions)

   Understanding how a ligand affects the steric and electronic properties of a metal is the cornerstone of the inorganic chemistry enterprise. What happens when the ligand is an extended surface? This question is central to the design and implementation of state-of-the-art functional materials containing transition metals. This perspective will describe how these two very different sets of extended surfaces can form well-defined coordination complexes with metals. In the Green formalism, functionalities on oxide surfaces react with inorganics to form species that contain X-type or LX-type interactions between the metal and the oxide. Carbon surfaces are neutral L-type ligands; this perspective focuses on carbons that donate six electrons to a metal. The nature of this interaction depends on the curvature, and thereby orbital overlap, between the metal and the extended π-system from the nanocarbon. 

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5. Tuning the electronic properties of the γ-Al ₂ O ₃ surface by phosphorus doping

   https://doi.org/10.1039/C9CP03105G  

   Acikgoz, Muhammed; Khoshi, M. Reza; Harrell, Jaren; Genova, Alessandro; Chawla, Rupali; He, Huixin; Pavanello, Michele (July 2019, Physical Chemistry Chemical Physics)

   Tuning the electronic properties of oxide surfaces is of pivotal importance, because they find applicability in a variety of industrial processes, including catalysis. Currently, the industrial protocols for synthesizing oxide surfaces are limited to only partial control of the oxide's properties. This is because the ceramic processes result in complex morphologies and a priori unpredictable behavior of the products. While the bulk doping of alumina surfaces has been demonstrated to enhance their catalytic applications ( i.e. hydrodesulphurization (HDS)), the fundamental understanding of this phenomenon and its effect at an atomic level remain unexplored. In our joint experimental and computational study, simulations based on Density Functional Theory (DFT), synthesis, and a variety of surface characterization techniques are exploited for the specific goal of understanding the structure–function relationship of phosphorus-doped γ-Al 2 O 3 surfaces. Our theoretical calculations and experimental results agree in finding that P doping of γ-Al 2 O 3 leads to a significant decrease in its work function. Our computational models show that this decrease is due to the formation of a new surface dipole, providing a clear picture of the effect of P doping at the surface of γ-Al 2 O 3 . In this study, we uncover a general paradigm for tuning support–catalyst interactions that involves electrostatic properties of doped γ-Al 2 O 3 surface, specifically the surface dipole. Our findings open a new pathway for engineering the electronic properties of metal oxides’ surfaces. 

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