Simultaneous Tuning Band Gaps of Cu₂O and TiO₂ to Form S‐Scheme Hetero‐Photocatalyst

Abstract

Photocatalytic Z or S scheme merits higher redox potentials and faster charge separation. However, heterostructure photocatalysts with band gaps of bulk materials often have a type I band structure leading to poor photocatalytic activity. In view of this, we report simultaneous tuning of band gaps of Cu 2 O and TiO 2 , where quantum dot Cu 2 O nanoparticles were formed on doped TiO 2 with Ti 3 + . The reduced size of Cu 2 O made its conduction band more negative, whereas the introduction of Ti 3 + made the absorption edge red shift to the visible light region. The as-formed heterostructure enabled an S-Scheme mechanism with remarkable activity and stability for visible light photodegradation of 4-chlorophenol (4-CP). The as-obtained photocatalysts' activity demonstrated ca. 510-fold increase as compared to individual ones and a mechanical blend. The asobtained photocatalysts maintained over 80 % for 5 cycles and 2 months exposure to O 2 did not decrease the degradation rate. ESR characterization and scavenger experiments proved the S-Scheme mechanism.

Role of Interfacial Morphology in Cu2O/TiO2 and Band Bending: Insights from Density Functional Theory

“…The heterostructures with different degrees of lattice mismatch (strain) were generated using the QuantumATK software developed by Synopsys, which provides a user-friendly setting to adjust the lattice vectors and align the crystal structures to create the desired heterostructures. In generating the interfaces, Cu 2 O was subjected to strain (treated as a film), a consequence of its deposition as the top layer in the Cu 2 O/TiO 2 fabrication process. , …”

“…In generating the interfaces, Cu 2 O was subjected to strain (treated as a film), a consequence of its deposition as the top layer in the Cu 2 O/TiO 2 fabrication process. 68 , 69 …”

“…In generating the interfaces, Cu 2 O was subjected to strain (treated as a film), a consequence of its deposition as the top layer in the Cu 2 O/ TiO 2 fabrication process. 68,69 ■ RESULTS AND DISCUSSION Surfaces. Determining suitable surface orientations for the construction of a heterostructure poses a challenge due to its impact on band bending characteristics.…”

Oxygen vacancy enhanced photocatalytic activity of Cu2O/TiO2 heterojunction

“…In theory, the difference in band structure between TiO 2 and Cu 2 O can easily lead to the formation of type Ⅱ heterojunctions, 6 S-type heterojunctions, 7 and Z-type heterojunctions. 8 However, TiO 2 and Cu 2 O may not form heterostructures during preparation, or the resulting heterostructures may not significantly improve catalytic activity.…”