Graphitic carbon nitride (g-C3N4) was synthesized from three different precursors such as urea, thiourea and mixture of urea and thiourea containing each in the ratio 1:1. The variation in the thermal decomposition and condensation pathways of precursors led to the formation of g-C3N4 with different morphological and photophysical aspects. These were loaded upon TiO2/bentonite nanocomposite to make it visible active. The g-C3N4 synthesized from urea (UC3) was found to be highly influential sensitizer due to its thin and long nanosheet-like morphology, and the nanocomposite prepared by loading of g-C3N4 on TiO2/bentonite (UC3TB) effectively degraded about 85% of the reactive brilliant red-X3BS (RBR-X3BS) dye under visible light irradiation. The high activity was attributed due to the high surface area and pore volume of the nanocomposite along with effective charge separation.