Physical and photo-electrochemical properties of oxygen-rich delafossite CuYO2.25

Fabrication of CuYO2 Nanofibers by Electrospinning and Applied to Hydrogen Harvest

Hydrogen can be employed as an alternative renewable energy source in response to climate change, global warming, and the energy problem. Methanol gas steam reforming (SRM) is the major method used in industry to produce hydrogen. In the SRM process, the catalyst nature offers benefits such as low cost, simplicity, and quickness. In this work, delafossite copper yttrium oxide (CuYO2) nanofibers were successfully prepared by electrospinning. The prepared CuYO2 nanofibers have different physical and chemical properties including thermoelectric behavior. The electrospinning method was used to produce as-spun fibers and annealed in an air atmosphere to form Cu2Y2O5 fibers; then, Cu2Y2O5 fibers were annealed in a nitrogen atmosphere to form CuYO2 nanofibers. X-ray diffraction studies and thermogravimetric and transmission electron microscope analysis confirmed the formation of CuYO2 nanofibers. The CuYO2 nanofibers were applied to methanol steam reforming for hydrogen production to confirm their catalytic ability. The CuYO2 nanofibers exhibited high catalytic activity and the best hydrogen production rate of 1967.89 mL min-1 g-cat-1 at 500 °C. The highly specific surface area of CuYO2 nanofibers used in steam reforming reactions could have significant economic and industrial implications. The performance of these CuYO2 nanofibers in hydrogen generation could be very important in industries with a global economic impact. Furthermore, the H2 production performance increases at higher reaction temperatures.

Anion Photoelectron Spectroscopy and Quantum Chemical Calculations of Bimetallic Oxide Clusters YCu2On-/0 (n = 2-5)

The structural and electronic properties of bimetallic oxide clusters, YCu₂O_n^- and YCu₂O_n (n = 2-5), are investigated using anion photoelectron spectroscopy and density functional theory calculations. The experimental vertical detachment energies of YCu₂O₂^-, YCu₂O₃^-, YCu₂O₄^-, and YCu₂O₅^- were measured to be 1.59, 1.76, 3.85, and 3.78 eV, respectively. Vibrationally resolved photoelectron spectra have been obtained for YCu₂O₂^-, with a spacing of 726 ± 80 cm^-1 assigned to the Y-O stretching vibrational mode. It is found that YCu₂O₂^- and YCu₂O₂ have C_2v symmetric planar five-membered ring structures. YCu₂O₃^- and YCu₂O₃ have C_2v symmetric planar six-membered ring structures. The most stable structure of YCu₂O₄^- is a quasi-planar structure which can be viewed as one O atom interacting with the Y atom of the YCu₂O₃ six-membered ring, while the most stable structure of YCu₂O₄ is a planar seven-membered ring. YCu₂O₅^- and YCu₂O₅ have nonplanar structures, which can be viewed as an O₂ unit interacting with the Y atom of the YCu₂O₃ six-membered ring. In YCu₂O_3,4,5^-/0, the Y-O and Cu-O bonds are dominant, while the Y-Cu and Cu-Cu interactions are weak.