Decorating Ag3PO4 nanodots on mesoporous silica-functionalized NaYF4:Yb,Tm@NaLuF4 for efficient sunlight-driven photocatalysis: synergy of broad spectrum absorption and pollutant adsorption-enrichment†
Efficiently harvesting solar energy for photocatalysis remains a challenge because near infrared (NIR) light with low excitation energy cannot be directly utilized by general semiconductor photocatalysts, although it makes up 46% of the solar spectrum. Herein, a broad-spectrum photocatalyst with pollutant adsorption-enrichment capability to enable natural sunlight-driven photocatalysis was synthesized by decorating a small amount of silver orthophosphate (Ag3PO4) nanodots on mesoporous silica (mSiO2)-functionalized upconversion nanoparticles (UCNPs; NaYF4:Yb,Tm@NaLuF4). The UCNPs play the role of broadening the absorption spectrum by upconverting NIR light into visible light, which can be absorbed by the Ag3PO4 nanodots. The functionalized hydrophilic mSiO2 shell not only facilitates the decoration of Ag3PO4 nanodots but is also capable of adsorbing and enriching pollutants around the Ag3PO4 nanodots to enhance the photocatalytic activity. Upon natural sunlight irradiation, the as-prepared photocatalyst (UCNP@mSiO2-Ag3PO4) exhibited remarkable photocatalytic activity with degradation rate constants of 0.24 and 0.051 min−1 under stirring and static conditions, exceeding that of the pure Ag3PO4 sample by factors of 4.2 and 12.5, respectively. Thus, it can be anticipated that the design of photocatalysts with the synergy of broadband absorption and pollutant adsorption-enrichment will be a promising strategy to realize efficient sunlight-driven photocatalysis, even without extra mechanical stirring for future scaled-up water treatment.