Oxide-derived copper (OD-Cu) materials exhibit extraordinary catalytic activities in the electrochemical carbon dioxide reduction reaction (CORR), which likely relates to non-metallic material constituents formed in transitions between the oxidized and the reduced material. In time-resolved operando experiment, we track the structural dynamics of copper oxide reduction and its re-formation separately in the bulk of the catalyst material and at its surface using X-ray absorption spectroscopy and surface-enhanced Raman spectroscopy. Surface-species transformations progress within seconds whereas the subsurface (bulk) processes unfold within minutes. Evidence is presented that electroreduction of OD-Cu foams results in kinetic trapping of subsurface (bulk) oxide species, especially for cycling between strongly oxidizing and reducing potentials. Specific reduction-oxidation protocols may optimize formation of bulk-oxide species and thereby catalytic properties. Together with the Raman-detected surface-adsorbed *OH and C-containing species, the oxide species could collectively facilitate *CO adsorption, resulting an enhanced selectivity towards valuable C products during CORR.
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http://dx.doi.org/10.1038/s42004-024-01151-0 | DOI Listing |
ACS Nano
December 2024
State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
Surface engineering is sought to stabilize nickel-rich layered oxide cathodes in high-energy-density lithium-ion batteries, which suffer from severe surface oxygen loss and rapid structure degradation, especially during deep delithiation at high voltages or high temperatures. Here, we propose a well-designed oxygen-constraining strategy to address the crisis of oxygen evolution. By integrating a La, Fe gradient diffusion layer and a LaFeO coating into the Ni-rich layered particles, along with incorporating an antioxidant binder into the electrodes, three progressive lines of defense are constructed: immobilizing the lattice oxygen at the subsurface, blocking the released oxygen at the interface, and capturing the residual singlet oxygen on the external surface.
View Article and Find Full Text PDFJ Hazard Mater
December 2024
Faculty of Enginnering, Gifu University, Gifu, Japan.
Oxidation states and distribution of arsenic (As) in annually laminated (varved) lacustrine deposits were analyzed with a seasonal resolution. This deposit was formed in the mid-Holocene landslide-dammed paleolake in the upper reaches of the Ane River, central Japan and the paleolake watershed consists of the Jurassic accretionary complexes (Mino-Tamba belt) including sedimentary and igneous rocks. In the outcrop, centimeter-to-decimeter-scale silty clay layers alternating with laminated layers are well developed.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Collaborative Innovation Center of Chemistry for Energy Material, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Key Laboratory of Computational Physical Science, Department of Chemistry, Fudan University, Shanghai 200433, China.
Rh-hydride phases were believed to be key causes of the exceptional catalytic ability of Rh catalysts under H reductive conditions. Here, we utilize the large-scale machine-learning-based global optimization to explore millions of Rh bulk, surface, and nanoparticle structures in contact with H, which rules out the presence of subsurface/interstitial H in Rh and Rh-hydride phases as thermodynamically stable phases under ambient conditions. Instead, an exceptional Rh-H affinity is identified for surface Rh atoms in Rh nanoparticles that can accommodate a high concentration of adsorbed H, with the surface Rh to H ratio reaching ∼2.
View Article and Find Full Text PDFACS Appl Mater Interfaces
December 2024
Department of Surface and Plasma Science, Charles University, Prague 18000, Czech Republic.
Perovskites exhibit outstanding performance in applications such as photocatalysis, electrochemistry, or photovoltaics, yet their practical use is hindered by the instability of these materials under operating conditions, specifically caused by the segregation of alkali cations toward the surface. The problem arises from the bulk strain related to different cation sizes, as well as the inherent electrostatic instability of perovskite surfaces. Here, we focus on atomistic details of the surface-driven process of interlayer switching of alkali atoms at the inorganic perovskite surface.
View Article and Find Full Text PDFThe diversity and abundance of diagenetic textures observed in sedimentary rocks of the clay-sulfate transition recorded in the stratigraphic record of Gale crater are distinctive within the rover's traverse. This study catalogs all textures observed by the MAHLI instrument, including their abundances, morphologies, and cross-cutting relationships in order to suggest a paragenetic sequence in which multiple episodes of diagenetic fluid flow were required to form co-occurring color variations, pits, and nodules; secondary nodule populations; and two generations of Ca sulfate fracture-filling vein precipitation. Spatial heterogeneities in the abundance and diversity of these textures throughout the studied stratigraphic section loosely correlate with stratigraphic unit, suggesting that grain size and compaction controls on fluid pathways influenced their formation; these patterns are especially prevalent in the Pontours member, where primary stratigraphy is entirely overprinted by a nodular fabric, and the base of the stratigraphic section, where increased textural diversity may be influenced by the underlying less permeable clay-bearing rocks of the Glen Torridon region.
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