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 (•O2–)) 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 (∼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 (•O2–) 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 •O2– 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.