Engineering Cationic Sulfur-Doped Co3O4 Architectures with Exposing High-Reactive (112) Facets for Photoelectrocatalytic Water Purification

Promoting the generation of intermediate active species (superoxide radical (O-center dot(2)-)) is an important and challenging task for water purification by photoelectrocatalytic (PEC) oxidation. Herein, we have constructed hierarchical cationic sulfur-doped Co3O4 architectures with controllable morphology and highly exposed reactive facets by introducing L-cysteine as a capping reagent and sulfur resource via a one-step hydrothermal reaction. The as-obtained cationic sulfur (1.8 mmol L-cysteine) source doped Co3O4 (SC-1.8) architectures with highly exposed (112) facets exhibited superior PEC activities and long-term stability (similar to 25,000 s) in 1.0 mol.L-1 sulfuric acid for an accelerated reactive brilliant blue KN-R degradation test. Our experimental and theoretical results confirmed that the superior PEC performance of the SC-1.8 architectures could be ascribed the following factors: (1) the highly exposed reactive (112) facets of SC-1.8 promoted carrier transport and diffusion during the PEC process and facilitated separating the electron/hole pairs and producing the predominant active species (O-center dot(2)-) compared with currently used other electrodes. (2) Cationic sulfur doped on the lattice of Co3O4 can narrow the band gap to extend the photoadsorption range and improve the lifetime of O-center dot(2)- to enhance the PEC efficiency. This work not only proves that the SC-1.8 architectures with highly exposed (112) facets are a promising PEC catalyst due to increasing the electron transport and the lifetime of active species but also presents a new strategy for constructing an active PEC catalyst.

Automated summary

The study successfully constructed hierarchical cationic sulfur-doped Co3O4 architectures with highly exposed (112) facets by introducing L-cysteine, showing superior PEC activities and long-term stability. The highly exposed reactive facets promoted carrier transport and diffusion during the PEC process, while cationic sulfur doping on the lattice of Co3O4 narrowed the band gap to extend the photoadsorption range and improve the lifetime of active species. This work proves that the SC-1.8 architectures with highly exposed (112) facets are a promising PEC catalyst and presents a new strategy for constructing an active PEC catalyst.