Fabricating α-MnO2@NiMoO4 Heterostructure Architecture With Superior Photoelectrocatalytic Water Purification

Abstract

Heterostructure catalyst is highly efficient for photoelectrolytic (PEC) wastewater remediation, while rationally constructing the photoelectrocatalyst with a high-quality interface is still challenging. Herein, a simple hydrothermal process prepares a heterostructure NiMoO₄@α-MnO₂ with a uniform interface between NiMoO₄ nanosheets and α-MnO₂ nanowires. NiMoO₄@α-MnO₂ exhibited significant advantages as follows: (1) α-MnO₂ nanowires act as charge transport channels like the arteries that transport nutrients, promoting the migration and separation of induced charges; (2) the pollutants can be electrostatically concentrated to the surface of the NiMoO₄@α-MnO₂. Specifically, the gossamer-like NiMoO₄ nanosheets adhering on the surface of the α-MnO₂ have a large surface area, beneficial for electrolyte penetration and utilization of active sites. (3) Unfolded gossamer-like NiMoO₄, like a vast extended solar panel of an artificial satellite, can harvest more solar energy, generating lots of electron (e⁻)/hole (h⁺) pairs and active species, offering multiple transfer pathways and speeding up the rate of the degradation reaction. The optimized heterostructured NiMoO₄@α-MnO₂-3.5 catalysts showed superior PEC activity and remarkable stability for degrading reactive brilliant blue KN-R. Z-scheme heterojunction between α-MnO₂ and NiMoO₄ is proposed based on their energy band structure and free radical quenching experiment.