Nonmetal Plasmon-Induced Carrier Backflow and Prolonged Lifetime for CO₂ Photoreduction

Constructing traditional heterojunctions involving noble metal cocatalysts is a well-established strategy for boosting photocatalytic efficiency by separating electron/hole pairs and improving light absorption through localized surface plasmon resonance (LSPR) effects. However, the high cost and limited availability of noble metals constrain their application, while the impact of plasmon effects on charge carrier dynamics and lifetimes, crucial for regulating photocatalytic performance, has been overlooked. Here, we propose integrating graphitic carbon dots (CDs) as proficient nonmetal cocatalysts into SnO2 nanofibers to facilitate high-efficiency photoreactions. Under light irradiation, photoelectrons within the SnO2 migrate to the CDs driven by the bent bands and the internal electric field, alongside inherent free electrons, stimulating into high-energy excited electrons due to LSPR effects. These energized electrons subsequently backflow to the SnO2 for stabilization, initiating a cyclic process that effectively prolongs carrier lifetimes within the SnO2/CDs nanohybrids, as confirmed by femtosecond transient absorption spectroscopy. Synergizing with enhanced optical absorption and CO2 chemisorption facilitated by the CDs, the resulting SnO2/CDs nanofibers demonstrate improved CO2 photoreduction performance.