Highly dispersed ZnO/g-C₃N₄ composites with different doping ratios of g-C₃N₄ were prepared by a hydrothermal method. The preparation method is simple and the energy consumption is low. The composite samples were used to degradate the methyl orange solution. They all showed excellent photocatalytic activity and cycling stability. The optimal loading content of g-C₃N₄ was investigated, and the mechanism of enhanced photocatalytic activity was studied in detail. This study provides a promising photocatalytic material for the removal of organic pollutants.

Dumbbell Ag₂CO₃–ZnO heterojunctions were synthesized for the first time via a simple in situ precipitation method. The as-prepared Ag₂CO₃–ZnO heterojunction showed high photocatalytic activity in the decomposition of methyl orange aqueous solution under simulated solar irradiation. The high improvement of photocatalytic activity compared to that of pure ZnO can be attributed to the formation of the Ag₂CO₃–ZnO heterojunction. Furthermore, the mechanism of photocatalytic activity was investigated in detail. The free radical trapping experiments indicated that the superoxide radical (·O₂^–) was an important active species in the photocatalytic process. This paper provides a new prospect for the preparation of photocatalysts with high catalytic performance in the degradation of dye wastewater.