In situ grown oxygen-vacancy-rich copper oxide nanosheets on a copper foam electrode afford the selective oxidation of alcohols to value-added chemicals

Abstract

Selective oxidation of low-molecular-weight aliphatic alcohols like methanol and ethanol into carboxylates in acid/base hybrid electrolytic cells offers reduced process operating costs for the generation of fuels and value-added chemicals, which is environmentally and economically more desirable than their full oxidation to CO2. Herein, we report the in-situ fabrication of oxygen-vacancies-rich CuO nanosheets on a copper foam (CF) via a simple ultrasonication-assisted acid-etching method. The CuO/CF monolith electrode enables efficient and selective electrooxidation of ethanol and methanol into value-added acetate and formate with ~100% selectivity. First principles calculations reveal that oxygen vacancies in CuO nanosheets efficiently regulate the surface chemistry and electronic structure, provide abundant active sites, and enhance charge transfer that facilitates the adsorption of reactant molecules on the catalyst surface. The as-prepared CuO/CF monolith electrode shows excellent stability for alcohol oxidation at current densities >200 mA·cm2 for 24 h. Moreover, the abundant oxygen vacancies significantly enhance the intrinsic indicators of the catalyst in terms of specific activity and outstanding turnover frequencies of 5.8k s−1 and 6k s−1 for acetate and formate normalized by their respective faradaic efficiencies at an applied potential of 1.82 V vs. RHE.

Investigation of Vacancies Transport in the Bilayer of the Cu2O1–x/CuO1–y Resistive Switching Device and Effect of Growth Temperature on Memristive Switching

“…V Cu is a dopant for both CuO 1– y and Cu 2 O 1– x but its doping efficiency is remarkably different in the two materials. V Cu defect level in CuO 1– y is 0.08 eV above the valence band (Figure d). ,,, The shallow defect ionizes almost completely at room temperature. The V Cu defect level in Cu 2 O 1– x is ∼4 times deeper, nearly 0.3 eV above the valence band (Figure d). ,,− This indicates that unlike CuO 1– y , the Cu 2 O 1– x defect does not fully ionize at room temperature.…”

“…V Cu defect level in CuO 1– y is 0.08 eV above the valence band (Figure d). ,,, The shallow defect ionizes almost completely at room temperature. The V Cu defect level in Cu 2 O 1– x is ∼4 times deeper, nearly 0.3 eV above the valence band (Figure d). ,,− This indicates that unlike CuO 1– y , the Cu 2 O 1– x defect does not fully ionize at room temperature. We experimentally confirmed this behavior using UPS (Figure c).…”

“…Most metal oxide semiconductors are n-type due to oxygen vacancy (V o ). − However, copper oxides are p-type due to the preponderance of copper vacancies (V Cu ). Among these, V Cu is the dominant point defect because its formation energy is lower. ,− The V Cu are primarily responsible for p-type conductivity in copper oxides. − …”

Submerged Photosynthesis of TiO2-CuO Hetero-nanoparticles for the Solar Photo-electrolysis of Multiple Environmental Hazardous Substances

“…The main peak, located at around 529 eV, corresponds to the lattice O 1s peak. The smaller peak at 531 eV is attributed to oxygen vacancies in CuO [44,45]. These results indicate that there are oxygen vacancies on the surfaces of all TCO hetero particles.…”

Investigating the role of oxygen vacancies in metal oxide for enhanced electrochemical reduction of NO3− to NH3: mechanistic insights

“…These peaks corresponded to lattice oxygen (O1), oxygen vacancy (O2), and surface-adsorbed oxygen species (O3), respectively. 200 The Cu-Co 3 O 4− x sample contained 25.9% OVs, which was considerably higher than the oxygen vacancy content of Co 3 O 4 (17.2%), demonstrating that the increased concentration of oxygen vacancies was successfully achieved in Cu-Co 3 O 4− x .…”