In this paper, a new metal-free photocatalyst (g-C3N4/C) coupled by graphitic carbon nitride (g-C3N4) and biomass carbon (waste paper used as carbon source) has been successfully synthesized. The g-C3N4/C exhibits obviously improved photocatalytic activity for degrading tetracycline, the degradation rate is more than 80%. It is more than four times than that of pure g-C3N4. Based on the structure and morphology characterization, the as-prepared g-C3N4/C represents a porous structure, which can provide a large surface area, increase the transmission route of photo-generated carriers and suppress the charge recombination. In addition, the capture experiments and ESR exploration show that both the h(+), center dot OH and center dot O(2)(-)play the important roles in this metal-free photocatalytic reaction. More importantly, our work not only designs a better photocatalytic material, but also provides a new thinking for, waste recycling which coincides with the concept of sustainable development (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.