Carbon dots modified bismuth antimonate for broad spectrum photocatalytic degradation of organic pollutants: Boosted charge separation, DFT calculations and mechanism unveiling

Abstract

• A novel CDs-BiSbO 4 photocatalyst was successfully fabricated. • The CDs in CDs-BiSbO 4 composite displayed excellent up-converted property. • The optimal composite exhibited enhanced photocatalytic degradation performance. • A strong interfacial interaction exists in the interlayer of CDs and BiSbO 4 . • The degradation pathways were proposed in detail by analyzing the intermediates. Developing a photocatalyst that simultaneously has broad spectral response and strong redox property of photoinduced carriers still remains challenging. Herein, carbon dots modified BiSbO 4 composites (CDs-BiSbO 4 ) were synthesized via a simple ultrasonication-calcination method without changing the electron property in the bulk of BiSbO 4 and perfectly reserving its strong oxidation ability. The admirable up-converted property of CDs efficiently converts long wavelength from 550 to 900 nm to short wavelength from 320 to 500 nm, endowing BiSbO 4 with a broad spectral response property. Moreover, CDs can serve as electron sinks, greatly inhibiting the recombination of photoinduced carriers originated from BiSbO 4 . X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations together validate a strong electron screening effect exists between the interlayer of CDs and BiSbO 4 , forming an ultrahigh electron transfer tunnel at the interlayer. More interestingly, the adsorption energy (E ads ) of O 2 onto CDs (−0.338 eV) was more negative than that onto BiSbO 4 (−0.230 eV), demonstrating the O 2 adsorbed on the CDs is more stable than that on BiSbO 4 . When O 2 molecules are adsorbed on the surface of CDs, all electrons at the interlayer are inclined to accumulate on O 2 , offering an ideal platform for the activation of molecular oxygen. This work offers an idea for constructing novel photocatalysts with both powerful redox property and broad spectral response for efficient photocatalytic degradation of organic pollutants.