Chemical information from XPS: Theory and experiment for Ni(OH)2.

The features and the electronic character of the states for the Ni 2p x-ray photoelectron spectroscopy (XPS) of Ni(OH)2 were analyzed. This detailed analysis is based on ab initio molecular orbital wavefunctions for a cluster model of Ni(OH)2. The theory is validated by comparison with experiment.

Parts-Per-Million Carbonate Mineral Quantification with Thermogravimetric Analysis-Mass Spectrometry.

Mitigating the deleterious effects of climate change requires the development and implementation of carbon capture and storage technologies. To expand the monitoring, verification, and reporting (MRV) capabilities of geologic carbon mineralization projects, we developed a thermogravimetric analysis-mass spectrometry (TGA-MS) methodology to enable quantification of <100 ppm calcite (CaCO) in complex samples. We extended TGA-MS calcite calibration curves to enable a higher measurement resolution and lower limits of quantification for evolved CO from a calcite-corundum mixture.

Facet-dependent dispersion and aggregation of aqueous hematite nanoparticles.

Nanoparticle aggregates in solution controls surface reactivity and function. Complete dispersion often requires additive sorbents to impart a net repulsive interaction between particles. Facet engineering of nanocrystals offers an alternative approach to produce monodisperse suspensions simply based on facet-specific interaction with solvent molecules.

Photolysis of Dissolved Organic Matter over Hematite Nanoplatelets.

Solar photoexcitation of chromophoric groups in dissolved organic matter (DOM), when coupled to photoreduction of ubiquitous Fe(III)-oxide nanoparticles, can significantly accelerate DOM degradation in near-surface terrestrial systems, but the mechanisms of these reactions remain elusive. We examined the photolysis of chromophoric soil DOM coated onto hematite nanoplatelets featuring (001) exposed facets using a combination of molecular spectroscopies and density functional theory (DFT) computations. Reactive oxygen species (ROS) probed by electron paramagnetic resonance (EPR) spectroscopy revealed that both singlet oxygen and superoxide are the predominant ROS responsible for DOM degradation.

Accumulation mechanisms for contaminants on weak-base hybrid ion exchange resins.

Mechanism of hexavalent chromium removal (Cr(VI) as CrO) by the weak-base ion exchange (IX) resin ResinTech® SIR-700-HP (SIR-700) from simulated groundwater is assessed in the presence of radioactive contaminants iodine-129 (as IO), uranium (U as uranyl UO), and technetium-99 (as TcO), and common environmental anions sulfate (SO) and chloride (Cl). Batch tests using the acid sulfate form of SIR-700 demonstrated Cr(VI) and U(VI) removal exceeded 97%, except in the presence of high SO concentrations (536 mg/L) where Cr(VI) and U(VI) removal decreased to ≥ 80%. However, Cr(VI) removal notably improved with co-mingled U(VI) that complexes with SO at the protonated amine sites.

Facile Metal Release from Pore-Lining Phases Enables Unique Carbonate Zonation in a Basalt Carbon Mineralization Demonstration.

Carbon-negative strategies such as geologic carbon sequestration in continental flood basalts offers a promising route to the removal of greenhouse gases, such as CO, via safe and permanent storage as stable carbonates. This potential has been successfully demonstrated at a field scale at the Wallula Basalt Carbon Storage Pilot Project where supercritical CO was injected into the Columbia River Basalt Group (CRBG). Here, we analyze recovered post-injection sidewall core cross-sections containing carbonate nodules using μ-XRF chemical mapping techniques that revealed compositional zonation within the nodules.

Interplay between Facets and Defects during the Dissociative and Molecular Adsorption of Water on Metal Oxide Surfaces.

Surface terminations and defects play a central role in determining how water interacts with metal oxides, thereby setting important properties of the interface that govern reactivity such as the type and distribution of hydroxyl groups. However, the interconnections between facets and defects remain poorly understood. This limits the usefulness of conventional notions such as that hydroxylation is controlled by metal cation exposure at the surface.

Main and Satellite Features in the Ni 2p XPS of NiO.

The origin and assignment of the complex main and satellite X-ray photoelectron spectroscopy (XPS) features of the cations in ionic compounds have been the subject of extensive theoretical studies using different methods. There is agreement that within a molecular orbital model, one needs to take into account different types of configurations. Specifically, those where a core electron is removed, but no other configuration changes are made and those where in addition to ionization, there are also shake or charge-transfer changes to the ionic configuration.

A microfluidic electrochemical cell for studying the corrosion of uranium dioxide (UO).

We have developed a specialized microfluidic electrochemical cell that enables investigation of the electrochemical corrosion of microgram quantities of redox active solids. The advantage of downscaling is the reduction of hazards, waste, expense, and greatly expanding data collection for hazardous materials, including radioactive samples. Cyclic voltammetry was used to monitor the oxidation-reduction cycle of minute quantities of micron-size uraninite (UO) particles, from the formation of hexavalent uranium (U(vi)), UO and reduction to UO .

Spontaneous Lithiation of Binary Oxides during Epitaxial Growth on LiCoO.

Epitaxial growth is a powerful tool for synthesizing heterostructures and integrating multiple functionalities. However, interfacial mixing can readily occur and significantly modify the properties of layered structures, particularly for those containing energy storage materials with smaller cations. Here, we show a two-step sequence involving the growth of an epitaxial LiCoO cathode layer followed by the deposition of a binary transition metal oxide.

Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion.

Rapid, selective, and in situ detection of pertechnetate (TcO) in multicomponent matrices consisting of interfering anions such as the ubiquitous NO and Cl or the isostructural CrO is challenging. Present sensors lack the selectivities to exclude these interferences or the sensitivities to meet detection limits that are lower than the drinking water standards across the globe. This work presents an affinity-based electrochemical sensor for TcO detection that relies on selective reductive precipitation of aqueous TcO induced by a 1,4-benzenedimethanethiol capture probe immobilized on an electrode platform.

Hierarchical Self-Assembly of a Water-Soluble Organoplatinum(II) Metallacycle into Well-Defined Nanostructures.

A water-soluble metallosupramolecular hexagon containing pendant methyl viologen (MV) and trimethylammonium units at the vertices has been synthesized via an organoplatinum(II) ← pyridyl coordination-driven self-assembly reaction. The MV units of the metallacycle were further utilized in the formation of a heteroternary complex with cucurbit[8]uril and a galactose-functionalized naphthalene derivative, yielding a metallacycle-cored carbohydrate cluster that was subsequently ordered into nanospheres and tapes, depending upon the concentration.

Orthogonal self-assembly of an organoplatinum(II) metallacycle and cucurbit[8]uril that delivers curcumin to cancer cells.

Curcumin (Cur) is a naturally occurring anticancer drug isolated from the plant. It is known to exhibit anticancer properties via inhibiting the STAT3 phosphorylation process. However, its poor water solubility and low bioavailability impede its clinical application.

Hexaaminobenzene as a building block for a Family of 2D Coordination Polymers.

A family of 2D coordination polymers were successfully synthesized through "bottom-up" techniques using Ni, Cu, Co, and hexaaminobenzene. Liquid-liquid and air-liquid interfacial reactions were used to realize thick (∼1-2 μm) and thin (<10 nm) stacked layers of nanosheet, respectively. Atomic-force microscopy and scanning electron microscopy both revealed the smooth and flat nature of the nanosheets.