Abstract:
Here, we present the integration of a commercially
available titanosilicate zeolite with photocatalyst graphitic carbon
nitride (g-C3N4) toward the development of an effective heterojunction
photocatalyst, TCN(1-8-8). The formation of this porous heterojunction
and its structural details have been confirmed by X-ray
diffraction, N2 adsorption, electron microscopy, thermogravimetric
analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron
spectroscopy. The visible light absorption and band structure
have been determined from diffused reflectance ultraviolet−visible
spectroscopy. For its fabrication, the contents of both the constituent
materials have been optimized systematically. Its photocatalytic activity
has been found to be impressive in the visible light-assisted degradation
of a variety of water pollutants (dyes and antibiotics) and in the
hydroxylation of phenol. Control experiments, radical scavenging/trapping experiments, influence of the reaction environment,
and photoelectrochemical measurements have been carried out to establish the structure−activity relationship and the plausible
reaction mechanisms. The various fragmented products, formed during the degradation of parent molecules, have been further
confirmed using electrospray ionization mass spectrometry analysis. The photocatalytic degradation of 98, 96, 95, and 92%; rate
constants of 0.0125, 0.01244, 0.0058, and 0.0040 min−1; and reduction of total organic concentrations of 63, 59, 57, and 55%
for rhodamine B, sulforhodamine B, tetracycline, and ciprofloxacin have been achieved in 6 h, respectively. The activity of
TCN(1-8-8) has been observed to be better than the state-of-the-art photocatalyst TiO2 (Degussa P25). Besides, it has also
exhibited excellent degradation activity in natural solar light. The effective adsorption of pollutant molecules over the active
surface, efficient charge separation at the interface, migration and retardation of charge carriers recombination process, and
tailored charge-carrier dynamics in the excited state have all been identified as reasons for the higher activity. This study,
therefore, provides a comprehensive and systematic grasp on the development of an economical catalyst for photocatalytic
hydroxylation reaction and wastewater treatment.
