In recent decades, the most common photocatalyst used in environmental applications has been TiO2, which exhibits a large band gap and can only be photoactivated under UV light. Therefore, the scientific interest has recently focused on the development of visible-light-activated photocatalysts such as g-C3N4. However, the photocatalytic performance of g-C3N4 is significantly hindered by the rapid recombination of photogenerated charges. An interesting approach to overcome this drawback is to fabricate Schottky junctions by combining g-C3N4 with materials demonstrating high metallicity.
In the present study, g-C3N4 was synthesized by forming a urea slurry that was dried and then calcinated at 550 oC for 4 h (CNU). The resulting CNU was ground and calcinated again at 550 oC for 2 h (3×) to achieve thermal exfoliation of its stacked 2D layers (CNUex3). In addition, a quantity of CNUex3 was then subjected to protonation using an HCl solution (pCNUex3). Ti3C2TX MXene was prepared via a top-down methodology using HF to achieve wet-chemical etching of the Al layers from the Ti3AlC2 Max Phase. Subsequently, low amounts of Ti3C2TX were coupled with either CNUex3 or pCNUex3 via a simple sonication methodology to form x%-CNMX or x%-pCNMX 2D/2D Schottky junctions (x = 1, 3 or 5), respectively. The structural, morphological and optical characteristics of all the synthesized materials were investigated using various characterization techniques (PXRD, SEM, ATR-FTIR, Raman spectroscopy, DRS, etc.). Furthermore, their photocatalytic performance was evaluated through laboratory-scale experiments using the antihypertensive drug Valsartan as a model pollutant, since it is commonly detected in various aquatic matrices. The results revealed that the combination of either CNUex3 or pCNUex3 with low amounts of Ti3C2TX improves their photocatalytic performance due to the successful suppression of exciton recombination as a result of the formation of a Schottky barrier at the interface of the two materials.