Design and synthesis of a UV–vis-NIR response heterostructure system: For efficient solar energy conversion and BPA photocatalytic degradation

Combining upconversion materials with narrow-wide bandgap semiconductors to construct heterostructured composite photocatalysts effectively improves solar energy conversion efficiency. NYF:Ln3+(Ln = Yb,Er,Tm)@BiOX(X = Cl,Br,I) heterostructures were prepared by a two-step hydrothermal method. This work explores the effects of different lanthanide ion doping and narrow-wide bandgap bismuth oxyhalides on the performance of the heterostructures system. Under near-infrared (NIR) light irradiation, NYF:Yb,Er,Tm@BiOI degraded 94 % BPA within 160 min. Significantly, compared with NYF:Yb,Er@BiOCl, NYF:Yb,Er@BiOBr and the NYF:Yb,Er,Tm/BiOI mechanical mixtures, the photocatalytic activity of NYF:Yb,Er,Tm@BiOI was increased by 9.4 times, 3.7 times and 1.8 times, respectively. The enhanced photocatalytic activity is attributed to the doping of Er-Tm double-activated ions, which provides multiple upconversion emissions and forms more overlap in the narrow bandgap BiOI absorption spectrum, making it advantageous to utilize upconversion light fully. Eventually, an underlying mechanism was proposed that the existence of FRET in the NYF:Yb,Er,Tm@BiOI heterostructure leads to enhanced photocatalytic activity. This work provides new insights into the design of advanced structures for NIR-responsive photocatalysts.