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

Abstract

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 α-MnO2@Co3O4 (MC) heterostructure that integrated 1D α-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 ∼ 88.44% and super long-term accelerated stability of ∼ 5000 s), which can be ascribed to its high oxygen evolution potential, large electrochemically active surface area, low charge transfer resistance, and low flat band potential. To gain insight into the significant photoelectric synergy, the type-II heterojunction between α-MnO2 and Co3O4 was proposed, effectively preventing photogenerated carriers' recombination and improving the dominant active species h+ and •O2− 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.