Nanocube-size-dependent Fermi level positioning in Cu2O/TiO2 S-scheme heterojunctions for optimized VOC photodegradation
Year: 2026
Type: article
Abstract: Precise control over interfacial energetics through nanoscale component engineering remains a key challenge in designing efficient heterojunction photocatalysts. This work demonstrates that the Fermi-level position of Cu 2 O—and consequently the interfacial electronic structure of Cu 2 O/TiO 2 S-scheme heterojunctions—can be directly tuned by varying Cu 2 O crystal size (edge lengths: 30, 55, and 315 nm). With a fixed 1 wt% loading, the heterojunction constructed from the smallest nanocubes (CT-30) achieves superior BTX oxidation efficiencies: 84.3% for benzene, 98.2% for toluene, and 94.1% for xylene, significantly outperforming pure TiO 2 , Cu 2 O, and the large-cube composite (CT-315). For toluene, this performance corresponds to an apparent quantum yield of 3.2% and a reaction rate of 6.04 µmol g⁻ 1 h⁻ 1 . Detailed electronic characterization shows that smaller Cu 2 O nanocubes have a more negative conduction band, enlarging the Fermi-level offset (ΔE F ) with TiO 2 . This strengthens the interfacial electric field, forming an efficient S-scheme photocatalysts that separates and preserves high-energy carriers. The retained electrons at the Cu 2 O conduction band (–0.79 V) drive abundant •O 2 ⁻/•OH generation, leading to complete BTX mineralization via intermediates to CO 2 /H 2 O. This work establishes size-mediated Fermi-level engineering as a key design principle for high-efficiency S-scheme photocatalysts.
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,490
Awards: G8265076883, G8970214479, G920264540
OpenAlex ID: W7208751732