Combining photocatalytic nitrogen fixation with antibiotic wastewater degradation reaction is of great significance. As a metal-free photocatalyst, g-C3N4 has great application prospect in the field of bifunctional photocatalytic reaction because of its abundant raw materials, simple preparation method, low toxicity, and high stability. However, the further development of g-C3N4 is limited by its wide band gap (2.7 eV) and high recombination rate of carriers. In this paper, AgInS2 nanospheres modified g-C3N4 nanosheets were successfully prepared by a simple hydrothermal method. The photocatalytic nitrogen fixation activity of the obtained AgInS2-g-C3N4 hybrid was nearly two times (91 μmol/h/g) higher than that of g-C3N4. In addition, by adding a proper amount of tetracycline pollutant into the photocatalytic system, the photocatalytic nitrogen fixation activity was further increased to 248 μmol/h/g, and the synergistic degradation of tetracycline environmental pollutants was realized. Through a series of experimental characterization and theoretical calculation, the morphology and carrier dynamics of photocatalyst were systematically explored. The results show that the introduction of AgInS2 nanospheres improves the utilization rate of sunlight, surface active sites and carrier transport rate of g-C3N4. This work provides references for the design of environmentally friendly photocatalysts and their applications in the fields of environmental purification and energy conversion.

The development of bifunctional reaction by combining CO2 reduction with antibiotics degradation is of great significance. Designing bifunctional catalysts with excellent performance is the focus of scholars' research. In this paper, Co-doped BiOBr ultra-thin nanosheets exposing rich (102) active crystal faces were prepared by one-step hydrothermal method. Since Co2+ has a smaller radius than Bi3+, Co was successfully incorporated into the lattice of BiOBr, which changed the crystal structure of BiOBr and obtained thinner nanosheets with rich lattice defects. The Gibbs free energy of CO2 reduction reaction was synergistically optimized by the combination of exposing (102) active crystal faces and introducing lattice defects. In addition, the addition of Co changed the band structure of BiOBr and improved the carrier separation ability, making Co-BiOBr be an excellent bi-functional photocatalyst for CO2 reduction and co-degradation of tetracycline, realizing the synergistic process of environmental purification and energy conversion. This work provides theoretical and experimental reference for the rational design of bifunctional photocatalysts.