Designing Waste Bioresource-derived Value-Added Nanohybrids for Efficient Photocatalysis Water Treatment

Although photocatalysis with ultraviolet-visible (UV-vis) light has made considerable advances, it is limited by the low efficiency of UV-vis energy conversion. To overcome this problem, UV-vis light can be replaced with near-infrared (NIR) light. Herein, we coupled eggshell-derived CaCO3 with a NIR-absorbing CuSe semiconductor and fabricated an insulator-based heterojunction structure. In application case studies of 4-nitrophenol (4-NP) and bacteria, the nanocomposites showed enhanced photocatalysis activity under NIR light induction. A first-principles calculation indicated that photoexcited electrons could transfer from the conduction band of CuSe to the conduction band of CaCO3. The main reactive species generated by the photocatalysis were ·CO3-, and ·OH free radicals. The antibacterial mechanisms of photocatalysis on the cell permeability and DNA layers of the bacterial cells were also revealed. Besides providing novel perspectives and mechanistic understanding of the fabrication of NIR light-driven photocatalysts, this study demonstrates the valorization of eggshell bio-wastes in environmental remediation.