A directional built-in electric field assisted 2D/1D g-C3N4/CeO2 S-scheme heterojunction for efficient RhB degradation and highly-selective CO2 photoreduction

This study synthesized a well-designed 2D/1D g-C3N4/CeO2 visible-light-driven photocatalyst through a straightforward approach. The binary photocatalyst emerged remarkable photo-degradation performance with a removal rate of 99.07% towards RhB in 120min and the k value of 0.0361 min−1, which maintained over 95% in four cycles. Fascinatingly more, highly-active converting CO2 to CH4 instead of CO during CO2 photo-reduction. The yield rate of CH4 reached 14.63 µmol·g−1·h−1, which was 26.13 folds than the CO generation rate (0.56 µmol·g−1·h−1). Moreover, the CH4 yield rate of g-C3N4/CeO2 heterojunction was 22.4 and 20.9 times improvement in comparison with pristine CeO2 nanorods and CN nanosheets, respectively. On account of HPLC-MS, ESR, active species scavenger investigation, and accurate energy-band structure analysis, a possible RhB degradation mechanism over 2D/1D g-C3N4/CeO2 heterojunction was elucidated. Meanwhile, an S-scheme mechanism with a built-in electric field was illuminated, which helped understand the preeminent photocatalytic performance. This research offers systematic insights into the preparation, activity, and mechanism of g-C3N4-based photocatalysts for environmental purification projects.