Energy level mediation of Bi2O2CO3 cooperates with the noble metal-like catalysis of Bi for enhancing the photodegradation activity of organic pollutants

The photocatalytic efficiency of Bi2O2CO3 is greatly limited by rapid recombination of photogenerated carriers. This is due to the fact that the conduction potential cannot meet the generation potential of superoxide radical, the accumulation of electrons accelerates its recombination with holes. Hence, I- doping strategy is used to regulate the energy band of Bi2O2CO3 to improve the reduction ability of valence band electrons to molecular oxygen, promote the efficient use of superoxide radicals and photogenerate holes in the degradation of pollutants. In addition, the solvent ethylene glycol in-situ reduces Bi3+ to Bi0, the tiny Bi0 particles are deposited onto BOC sheets, serving as cocatalysts similar to precious metals and enhancing the separation and transfer of photogenerated carriers. The results indicate that I-doping leads to a decrease in the work function of Bi2O2CO3 and an upward shift of the conduction band, which enhances the activation of molecular oxygen and the generation of superoxide radicals. The formation of Bi0/5I-Bi2O2CO3 not only promotes surface reaction, but also expands light absorption. The Bi0/5I-Bi2O2CO3 shows excellent photocatalytic activity for photodegradation of organism. After 60 min exposure to simulated sunlight, the UV–vis absorption peak of lignin at 280 nm disappeares completely, and the mineralization rate reaches 48.9 %. Rhodamine B only needs 1 min to completely fade. Where, vanillin is used as a lignin model, its degradation intermediates are determined by LCMS, and the possible photodegradation pathway is proposed in detail.