Due to the industry's rapid growth, the presence of organic pollutants, especially antibiotics, in water and wastewater resources is the main concern for wildlife and human health. Therefore, these days, a significant challenge is developing an efficient, sustainable, and eco-friendly photocatalyst. Natural biological models have numerous advantages compared to artificial model materials. Biological models with unique multi-level structures and morphology can be used to create porous bio-templates to produce hierarchical materials. So, in this work, for the first time, this was achieved by using sorghum grain seeds as a bio-template (natural waste material) and urea as a precursor, through a simple and environmentally friendly method. We believed that natural waste materials with high carbon atom content could be used as both a carbon doping agent and a bio-template, thus improving the physical and optical properties of the resulting materials. In comparison to previous studies on the synthesis of C-doped g-C3N4, our work offers a greener and more cost-effective approach to synthesis, while also reducing waste material. We succeeded in the photo-degradation of a series of organic pollutants such as phenol, bisphenol A (BPA), and amoxicillin (AMX) in an aqueous solution under solar light illumination.