Unveiling Hierarchical Dendritic Co₃O₄–SnO₂ Heterostructure for Efficient Water Purification

The construction of a desirable, environmentally friendly, and cost-effective nanoheterostructure photoanode to treat refractory organics is critical and challenging. Herein, we unveiled a hierarchical dendritic Co₃O₄-SnO₂ heterostructure via a sequential hydrothermal process. The time of the secondary hydrothermal process can control the size of the ultrathin SnO₂ nanosheets on the basis of the Ostwald solidification mass conservation principle. Ti/Co₃O₄-SnO₂-168h with critical growth size demonstrated a photoelectrocatalysis degradation rate of ∼93.3% for a high dye concentrate of 90 mg/L with acceptable long-term cyclability and durability over reported Co₃O₄-based electrodes because of the large electrochemically active area, low charge transfer resistance, and high photocurrent intensity. To gain insight into the photoelectric synergy, we proposed a type-II heterojunction between Co₃O₄ and SnO₂, which prevents photogenerated carriers' recombination and improves the generation of dominant active species •O₂⁻, ¹O₂, and h⁺. This work uncovered the Ti/Co₃O₄-SnO₂-168 as a promising catalyst and provided a simple and inexpensive assembly strategy to obtain binary integrated nanohybrids with targeted functionalities.