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

Developing a photocatalyst that simultaneously has broad spectral response and strong redox property of photoinduced carriers still remains challenging. Herein, carbon dots modified BiSbO4 composites (CDs-BiSbO4) were synthesized via a simple ultrasonication-calcination method without changing the electron property in the bulk of BiSbO4 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 BiSbO4 with a broad spectral response property. Moreover, CDs can serve as electron sinks, greatly inhibiting the recombination of photoinduced carriers originated from BiSbO4. 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 BiSbO4, forming an ultrahigh electron transfer tunnel at the interlayer. More interestingly, the adsorption energy (Eads) of O2 onto CDs (−0.338 eV) was more negative than that onto BiSbO4 (−0.230 eV), demonstrating the O2 adsorbed on the CDs is more stable than that on BiSbO4. When O2 molecules are adsorbed on the surface of CDs, all electrons at the interlayer are inclined to accumulate on O2, 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.