Atomic Molybdenum Dispersed on Graphitic Carbon Nitride Nanosheets for Photocatalytic Degradation of Antibiotics

High-performance photocatalysts are being intensively pursued for environmental remediation. In this work, atomic molybdenum (Mo) dispersed g-C3N4 (Mo/CN) photocatalyst was obtained via a three-step preparation process containing direct calcination, microwave hydrothermal treatment, and recalcination. Mo/CN displays a configuration of atomic Mo in-plane coordination with two N atoms of g-C3N4 in the big loop. A remarkable augmentation of specific surface area and construction of the amorphous–crystalline interface of Mo/CN are achieved. The specific surface area of the Mo/CN sample is ca. 1.8-fold of g-C3N4 without Mo incorporation (m-CN) and 7.7-fold of pristine g-C3N4 (p-CN), respectively. The introduction of Mo single atom narrows the energy band of g-C3N4, slows down the combination of photogenerated carriers, and promotes the adsorption of O2 molecules over g-C3N4. The optimal Mo/CN-0.075 exhibits an enhanced photocatalytic activity toward antibiotics with a removal efficiency of tetracycline reaching 92.1%, higher than m-CN (74.0%) and p-CN (50.8%) as well as most of the other reported g-C3N4-based photocatalysts. Active species •O2– and 1O2 play a dominant role in the photocatalytic removal of the antibiotics. The growth experiment of hemp peas and treatment of local printing and dyeing wastewater show a possible real-world application of Mo/CN-0.075. This work offers some insights into the improvement of g-C3N4-based photocatalysts with high surface area and tailored electronic properties for efficacious wastewater treatment.