Fast electron transfer and enhanced visible light photocatalytic activity of silver and Ag2O co-doped titanium dioxide with the doping of electron mediator for removing gaseous toluene

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Volatile organic compounds (VOCs) can influence air quality and threaten human health; however, the development of an effective method to remediate toxic VOCs is still remain challenge. Herein, a novel silver and Ag2O co-doped TiO2 with fast electron transfer modified by nitrogen doping carbon dots was prepared via a facile chemical precipitation-reduction method. Under 50 min of visible light irradiation, the novel photocatalyst exhibited approximately 50% gaseous toluene degradation efficiency, which was ca. 9.7 times and 2.2 times higher than that of bare TiO2 and silver and Ag2O co-doped TiO2, respectively. Importantly, the photocatalyst also showed a stable structure and good recycling ability after 400 min of photocatalytic degradation with little amount of NCDs. Besides, the up-conversion effect of NCDs could emit high-energetic light and thus generate more e−-h+ pairs, which could facilitate the SPR effect of Ag and thus showed strong visible light response because of the localized surface plasmon resonance (LSPR) excitation. Thus, the excellent photocatalytic performance could attribute to the synergetic effect of up-conversion effect of NCDs and SPR effect of silver which could both facilitate charge carriers separation and improve visible-light response. Finally, a possible mechanism for the excellent photocatalytic activity was proposed, in which the active species including ·O2−, ·OH and h+ were generated and contributed to photocatalytic process. The successful fabrication of DACT provides a potential strategy for the treatment of VOCs in practical applications.