Atomic layer deposition (ALD) is a viable means to add corrosion protection to copper metal. Ultrathin films of AlO, TiO, ZnO, HfO, and ZrO were deposited on copper metal using ALD, and their corrosion protection properties were measured using electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). Analysis of ∼50 nm thick films of each metal oxide demonstrated low electrochemical porosity and provided enhanced corrosion protection from aqueous NaCl solution. The surface pretreatment and roughness was found to affect the extent of the corrosion protection. Films of AlO or HfO provided the highest level of initial corrosion protection, but films of HfO exhibited the best coating quality after extended exposure. This is the first reported instance of using ultrathin films of HfO or ZrO produced with ALD for corrosion protection, and both are promising materials for corrosion protection.
The
sequential vapor infiltration (SVI) method, based on atomic
layer deposition chemistry, allows the creation of a polymer–inorganic
hybrid material through the diffusion of metal–organic vapor
reagents into a polymer substrate. This study investigates the reactivity
of the ester, amide, and carboxylic acid functional groups of poly(methyl
methacrylate) (PMMA), poly(vinylpyrrolidone) (PVP), and poly(acrylic
acid) (PAA), respectively, in the presence of trimethylaluminum (TMA)
vapor. This work explores the possible reaction mechanisms of these
functional groups through in situ Fourier transform infrared spectroscopy
and ab initio quantum chemical analysis. At temperatures of ≤100
°C, TMA physisorbs to the carbonyl groups of PMMA. As the temperature
is increased, TMA forms a covalent bond with PMMA. TMA physisorbs
to PVP and then partially desorbs in the presence of water for all
studied temperatures of ≤150 °C. PAA readily reacts with
TMA to form a covalent bond with the carbonyl group at 60 °C.
This increased reactivity is attributed to the acidic proton in the
carboxylic acid moiety based on TMA’s reactivity with hydroxyl-terminated
surfaces and ab initio calculations. At temperatures of ≥100
°C, TMA catalyzes anhydride formation in PAA. These insights
will help with the prediction of chemical interactions in SVI processes
for the development of organic–inorganic hybrid materials.
The lithium supply issue mainly lies in the inability of current mining methods to access lithium sources of dilute concentrations and complex chemistry. Electrochemical intercalation has emerged as a highly selective method for lithium extraction; however, limited source compositions have been studied, which is insufficient to predict its applicability to the wide range of unconventional water sources (UWS). This work addresses the feasibility and identifies the challenges of Li extraction by electrochemical intercalation from UWS, by answering three questions: 1) Is there enough Li in UWS? 2) How would the solution compositions affect the competition of Li
+
to major ions (Na
+
/Mg
2+
/K
+
/Ca
2+
)? 3) Does the complex solution composition affect the electrode stability? Using one-dimensional olivine FePO
4
as the model electrode, we show the complicated roles of major ions. Na
+
acts as the competitor ion for host storage sites. The competition from Na
+
grants Mg
2+
and Ca
2+
being only the spectator ions. However, Mg
2+
and Ca
2+
can significantly affect the charge transfer of Li
+
and Na
+
, therefore affecting the Li selectivity. We point to improving the selectivity of Li
+
to Na
+
as the key challenge for broadening the minable UWS using the olivine host.
A review detailing existing electrode materials, cell architectures, and charge transfer mechanisms related to electrochemically driven desalination and selective element extraction in aqueous environments.
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