Unique insights into photocatalytic VOCs oxidation over WO3/carbon dots nanohybrids assisted by water activation and electron transfer at interfaces.

Internal electric field (IEF) at heterojunction interfaces can separate photoexcited charge carriers and promote photocatalytic performance. Here we have modified WO3 nanoplates with carbon dots (CDs) and constructed an interfacial IEF directing from CDs to WO3 with assistance of their remarkably different work functions. Such electric field drove photoexcited electrons to transport towards CDs and retained photoexcited holes to stay at WO3, achieving electron/hole spatial separation. H2O preferred chemisorption on the five-coordinated W atoms of WO3 with an elongated H-O bond and bent H-O-H angle, which allowed the activation of H2O and favorable production of ·OH radicals. The WO3/CDs (WC1) showed a superior photocatalytic activity for visible-light photooxidation of HCHO and CH3COCH3 with CO2 production rate of 411 and 188 µmol g-1 h-1, respectively, outperforming most of WO3-based photocatalysts. The enhanced photocatalytic performance correlated with the IEF-induced charge separation, favorable ·OH production and VOCs chemisorption. Our work confirms the role of CDs cocatalyst in the photocatalytic oxidation of VOCs, which will inspire enthusiasm to develop more advanced heterojunction photocatalysts involving carbon nanomaterials.