Fabrication and Comparison of Carbon Dots/Titanium Dioxide Photocatalysts with Different Precursors for Enhanced Wastewater Purification

Abstract

Controlled deposition of co-catalysts on requisite surfaces is highly crucial for myriad applications related to photocatalysis, energy conversion, and sunlight response. Here, carbon dots (CDs)-doped TNs (CDs/TNs), which possess high photocatalytic activity and wastewater purification ability, are synthesized using different precursors of CDs (citric acid: CA and ammonium citrate: AC) respectively. By simply replacing the precursor, the photodegradation efficiency and capacity can be directly enhanced to acquire satisfied results towards the removal of organic pollutants. The prepared CA-CDs/TNs and AC-CDs/TNs are compared using different techniques, including Fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), UV-vis spectrophotometry and electrochemical, and the results are discussed in detail. Benefited from the powerful synergistic effects between the incorporated CDs and TNs, the two CDs/TNs show excellent photocatalytic ability for the degradation of three representative pollutants (Congo-red: CR, Rhodamine B: RhB, and Tetracycline: TC) compared to pure TNs. Specially, based on the obtained results, CA-CDs/TNs exhibit the highest degradation efficiency, having removed ~91.6% of CR, 90.2% of RhB and 96.1% of TC after 120min and 60min. Finally, the degradation fragments of the three pollutants were detected by liquid chromatography-tandem mass spectrometry, and feasible degradation pathways are discussed.

Keywords: wastewater purification, precursor, CDs/TNs, photodegradation efficiency