A type-II α-MnO2@Co3O4 architecture with superior photoelectrocatalytic performance toward water purification

Designing an environmentally friendly and cost-effective heterogeneous structure to treat refractory organic wastewater for long-term environmental benefits is a challenge in the photoelectrocatalytic (PEC) process, and one-dimensional (1D) semiconductor nanowires can be utilized as a suitable platform to interface with other components, constructing nanohybrids heterostructures with functionalities not found in the individual components. Herein, a two-step hydrothermal process prepared a necklace-like alpha-MnO2@Co3O4 (MC) heterostructure that integrated 1D alpha-MnO2 and Co3O4 octahedron with the exposed (111) facets. The optimized MC-2 with a suitable amount of Co3O4 exhibited superior PEC performance for removing reactive brilliant blue KN-R (KN-R) (removal rate of similar to 88.44% and super long-term accelerated stability of similar to 5000 s), which can be ascribed to its high oxygen evolution potential, large electrochemically active surface area, low charge transfer resistance, and low fiat band potential. To gain insight into the significant photoelectric synergy, the type-II heterojunction between alpha-MnO2 and Co3O4 was proposed, effectively preventing photogenerated carriers' recombination and improving the dominant active species h(+) and center dot O-2(-) generation. This work uncovered the MC-2 heterostructure for the PEC degradation of KN-R, guiding the other heterogeneous materials to decrease industrial costs and realize large-scale water purification applications.

Automated summary

Designing a cost-effective and environmentally friendly heterogeneous structure is challenging in the photoelectrocatalytic (PEC) process for treating refractory organic wastewater. This study introduces a necklace-like alpha-MnO2@Co3O4 (MC) heterostructure, which integrates 1D alpha-MnO2 and Co3O4 with exposed (111) facets. The optimized MC-2 exhibits superior PEC performance with a removal rate of 88.44% for reactive brilliant blue KN-R and a long-term stability of 5000 s. The type-II heterojunction between alpha-MnO2 and Co3O4 effectively prevents carrier recombination and enhances the generation of h(+) and center dot O-2(-) species. This work provides valuable insights for the PEC degradation of KN-R and guides the development of heterogeneous materials for large-scale water purification applications with reduced costs.