Oxygen-deficient photostable Cu₂O for enhanced visible light photocatalytic activity

Abstract

Oxygen vacancies in inorganic semiconductors play an important role in reducing electron-hole recombination, which may have important implications in photocatalysis. Cuprous oxide (Cu2O), a visible light active p-type semiconductor, is a promising photocatalyst. However, the synthesis of photostable Cu2O enriched with oxygen defects remains a challenge. We report a simple method for the gram-scale synthesis of highly photostable Cu2O nanoparticles by the hydrolysis of a Cu(i)-triethylamine [Cu(i)-TEA] complex at low temperature. The oxygen vacancies in these Cu2O nanoparticles led to a significant increase in the lifetimes of photogenerated charge carriers upon excitation with visible light. This, in combination with a suitable energy band structure, allowed Cu2O nanoparticles to exhibit outstanding photoactivity in visible light through the generation of electron-mediated hydroxyl (OH˙) radicals. This study highlights the significance of oxygen defects in enhancing the photocatalytic performance of promising semiconductor photocatalysts.

Pompon Dahlia‐like Cu2O/rGO Nanostructures for Visible Light Photocatalytic H2 Production and 4‐Chlorophenol Degradation

“…Band energies were investigated by valence band XPS (Figure S4a–c); the VB potential maxima of hierarchical Cu 2 O and the Cu 2 O/rGO nanocomposite were +1.30 and +1.10 eV respectively relative to the Fermi level, and corresponding CB minima edges (derived from the optical band gap and valence band XP spectra) were −1.12 eV and −1.03 eV for Cu 2 O/rGO. The CB minimum is therefore unaffected by formation of the Cu 2 O/rGO heterojunction, albeit more negative than previous reports (e. g. −0.42 for oxygen‐deficient Cu 2 O nanoparticles), and in both cases much greater than required for photocatalytic hydrogen production from water (−0.65 eV at pH )…”

Significantly Enhanced Aqueous Cr(VI) Removal Performance of Bi/ZnO Nanocomposites via Synergistic Effect of Adsorption and SPR-Promoted Visible Light Photoreduction

“…However, compared with bare ZnO, all BiNPs/ZnO composites exhibited stronger adsorption intensity in the visible light region. At the same time, the band gap energy estimated from the intercepts of the tangents to the plots of (Ahν) 2 vs. photon energy was shown in Figure 5b [42,43], which also suggested that the band gap energy of the Bi-ZnO-80 composite was not significantly changed, as compared with that of pure ZnO. Therefore, the enhancement of absorption in the visible light region of BiNPs/ZnO was not due to the change of the band gap energy.…”

Reusable, Free‐Standing MoS2/rGO/Cu2O Ternary Composite Films for Fast and Highly Efficient Sunlight Driven Photocatalytic Degradation

“… and are edge potential of conduction and valence band respectively. is the bandgap of the semiconductor, is the free electron energy on the hydrogen scale (4.5 eV) and χ is absolute electronegativity of the semiconductor. The value of χ for MoS 2 and Cu 2 O is 5.32 and 5.305 respectively …”

“…The absorption peak of MB at 664 nm, in Figure (a) also, show blue‐shift and decrease in absorption intensity (hypsochromic effect). This process corresponds to the de‐methylation of MB dye with various intermediate structures . Therefore, the ternary composite MoS 2 /rGO/Cu 2 O structure with its lowest recombination rate and separation efficiency of photogenerated charge carriers are responsible for the degradation phenomenon.…”