This thesis addresses the growing issue of environmental pollution, particularly water contamination, caused by expanding industries. It focuses on visible light-responsive photocatalysis using semiconductors, specifically graphitic carbon nitride (g-C₃N₄), as a sustainable solution for environmental remediation. The study explores the synthesis and photocatalytic use of g-C₃N₄-based composite materials, combined with other semiconductors to form binary hybrid heterostructures. These heterostructures enhance photoelectrochemical properties and optical absorption, making them highly effective for degrading pollutants when activated by visible light, such as sunlight. The research focuses on developing several binary hybrid nanocatalysts: g-C₃N₄/ZrO₂ (CZ) composed of spherical zirconium oxide nanoparticles on g-C₃N₄, g-C₃N₄/CuS (CS) featuring hexagonal copper sulfide nanoplates, and g-C₃N₄/BiOBr (BCN) with round-shaped bismuth oxy bromide nanoplates. These nanocatalysts are designed for efficient photocatalytic degradation of persistent organic and inorganic contaminants such as Cr(VI), methyl orange, methylene blue, and rhodamine B in aqueous solutions under sunlight exposure. In summary, the research on g-C₃N₄-based nanohybrid matters in this dissertation opens promising avenues for efficient nanocatalysis in the field of photocatalytic environmental remediation technologies. These advancements contribute in developing sustainable solutions to mitigate water pollution, ensuring a cleaner and healthier environment for the future.