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Bronze surfaces were modified by methyl, carboxyl and amino terminated phosphonic acids films to assess the impact of the terminal group and the film thickness on the corrosion resistance of coated samples. The structure of the adsorbed films was characterized by goniometry, specular IR, and SFG spectroscopy. Corrosion studies were conducted for three weeks of continuous immersion in acid rain solution using polarization measurements and electrochemical impedance spectroscopy. Films formed in 1 mM solutions of phosphonic acids provided better corrosion protection than those formed in 0.1 mM solutions. Carboxyl terminated phosphonic acid films exhibited the least protective film on bronze.

Photocatalytic splitting of water into hydrogen and oxygen by utilizing sunlight and a photocatalyst is a promising way of generating clean energy. Here, we report a molecular-level study on heavy water (D2O) interacting with TiO2 as a model photocatalyst. We employed the surface specific technique Sum-Frequency-Generation (SFG) spectroscopy to determine the nature of the hydrogen bonding environment and the orientation of interfacial water molecules using their OD-stretch vibrations as reporters. By examining solutions with various pD-values, we observe an intensity-minimum at around pD 5, corresponding to the balance of protonation and deprotonation of TiO2 (point of zero charge). The majority of water molecules' deuterium atoms point away from the interface when the pD is below 5, and point towards the surface when the pD is higher than 5, with strong hydrogen bonds towards the surface.

Funding Information: Financial support from the German Research Foundation through grant KU1980/14-1, the European Commission through ERC Starting Grant 336679, and the joint program by DAAD (57313835) and National Research Foundation of Korea (NRF-2016K2A9A2A14912842) is gratefully acknowledged. Y.M.J. was supported by the Academy of Finland (project no. 314862). A.S.F. was supported by the World Premier International Research Center Initiative (WPI), MEXT, Japan. Y.M.J. and J.T. acknowledge the use of the computational resources provided by the Aalto Science-IT project and CSC, Helsinki. We thank Hao Lu for the XPS experiments. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society. Mineral-water interfaces play an important role in many natural as well as technological fields. Fundamental properties of these interfaces are governed by the presence of the interfacial water and its specific structure at the surface. Calcite is particularly interesting as a dominant rock-forming mineral in the earth's crust. Here, we combine atomic force microscopy, sum-frequency generation spectroscopy, and molecular dynamics simulations to determine the position and orientation of the water molecules in the hydration layers of the calcite surface with high resolution. While atomic force microscopy provides detailed information about the position of the water molecules at the interface, sum-frequency generation spectroscopy can deduce the orientation of the water molecules. Comparison of the calcite-water interface to the interfaces of magnesite-water, magnesite-ethanol, and calcite-ethanol reveals a comprehensive picture with opposite water orientations in the first and second layer of the interface, which is corroborated by the molecular dynamics simulations.

The synergistic effects of area ratio and microstructure on the galvanic corrosion of A508/309 L/308 L dissimilar metals weld (DMW) are studied by a multi-analytical approach. It was demonstrated that decreasing the anode/cathode surface area ratio obviously enhances the corrosion rate of A508, both locally and globally. Deeper analyses of the AFM results enabled quantitative comparison of the corrosion behaviour of the different surface constituents. It was revealed that in the galvanic interaction of the DMW, the grain refined region corrodes most, followed by the partial grain refined region and base metal matrix of the A508, respectively. The electrochemical localization index (LI) estimation method and AFM analysis both confirmed the presence of a mixed (localized and uniform) corrosion phenomenon occurring on the surface of the A508 anode metal in the galvanic interaction of the dissimilar metals. Finally, the degree of synergism equation was utilized to describe the synergistic effects of anode/cathode area ratio and the microstructure of the samples on the galvanic corrosion of LAS A508/309L/308L SS DMW.

In the present study, the impact of copper substrate grain size on the structure of the succeeding electrodeposited nickel film and its consequent corrosion resistance in 3.5% NaCl medium were evaluated before and after functionalization with stearic acid. Nickel layers were electrodeposited on two different copper sheets with average grain size of 12 and 25 &micro, m, followed by deposition of stearic acid film through self-assembly. X-ray diffraction analysis of the electrodeposited nickel films revealed that the deposition of nickel film on the Cu substrate with small (12 &micro, m) and large (25 &micro, m) grains is predominantly governed by growth in the (220) and (111) planes, respectively. Both electrodeposited films initially exhibited a hydrophilic nature, with water-contact angles of 56&deg, and &lt, 10&deg, respectively. After functionalization with stearic acid, superhydrophobic films with contact angles of ~150&deg, were obtained on both samples. In a 3.5% NaCl medium, the corrosion resistance of the nickel layer electrodeposited on the copper substrate with 25 &micro, m grains was three times greater than that deposited on the copper substrate with 12 &micro, m grains. After functionalization, the corrosion resistance of both films was greatly improved in both short and long immersion times in 3.5% NaCl medium.

The synergestic role of boric acid, as a crystal modifier, and screw dislocation step defects on the crystal growth and formation mechanism of nickel micro-nanocones during electrocrystallization is explained using density functional theory (DFT) and Monte Carlo (MC) calculations. Earlier atomic force microscopy (AFM) studies provided direct evidences on the effect of boric acid on morphology distribution of nickel micro-nanocones and confirmed the presence of terraces and steps due to the spiral growth of screw dislocation. In the presence of boric acid, the formation of nickel-borate complex leads to a decrease in the system’s supersaturation and in turn provides an appropriate condition for screw dislocation driven-growth. DFT and MC simulations reveal that the nickel-borate complex primarily adsorb in the step edges with the lowest adsorption energy barrier, after which the crystal growth is inhibited on these edges resulting in the formation of nanocone structures.

In this study, we report on a combined microscopic, analytical and electrochemical characterization of the nanoscopic passive layer on a tungsten‑molybdenum-containing super duplex stainless steel. We used scanning transmission electron microscopy/energy dispersive X-ray spectroscopy, scanning Kelvin probe force microscopy, scanning tunneling spectroscopy, and Mott–Schottky electrochemical impedance spectroscopy analysis to correlate the local chemical composition and electronic properties of passive layers on austenite and ferrite phases. The passive layer on the ferrite phase contains a higher amount of Mo, W, and Cr, which accommodates a higher nobility of ferrite and a higher local energy of the band gap compared to those on the austenite. The two aforementioned phases exhibit a different composition and semi-conductive properties of their passive layers leading to dissimilar local corrosion susceptibility. These findings are of pivotal importance in further studies of austenite and ferrite phase resolved corrosion resistance of duplex stainless steel demanding a dedicated alloying strategy.

A new recycling and film formation scheme is developed for spent Li-ion batteries, which involves the combination of ascorbic-assisted sulfuric leaching and electrodeposition to fabricate a corrosion resistance superhydrophobic coating. The idea behind the simultaneous use of sulfuric and ascorbic is to benefit from the double effect of ascorbic acid, as a leaching reducing agent and as morphological modifier during electrodeposition. Quantum chemical calculations based on the density functional theory are performed to explain the cobalt-ascorbate complexation during the electrocristalization. The optimum parameters for the leaching step are directly utilized in the preparation of an electrolyte for the electrodeposition process, to fabricate a superhydrophobic film with a contact angle of &gt, 150° on plain carbon steel. The potentiodynamic polarization measurments in 3.5 wt % NaCl showed that boric-pulsed electrodeposited cobalt film has 20-times lower corrosion current density and higher corrosion potential than those on the non-coated substrate.