Visible light photocatalysis: efficient Z-scheme LaFeO3/g-C3N4/ZnO photocatalyst for phenol degradation.

In this work, a Z-scheme LaFeO3/g-C3N4/ZnO heterojunction photocatalyst with large specific surface (68.758 m2/g) and low cost (0.00035 times the cost of per gram of Au) was easily synthesized by glucose-assisted hydrothermal method. The structure, surface morphology, and optical properties of the photocatalyst were investigated. The constructed Z-scheme heterojunction catalysts can enhance the visible light absorption and carrier separation efficiency. Among these photocatalysts, the 10%-LaFeO3/g-C3N4/ZnO composite possesses the premium performance for efficient degrading 97.43% of phenol within 120 min. Even after 5 cycles, it still sustains an excellent photocatalytic stability (92.13% phenol degradation). According to the XPS surface states and the capture of active species on LaFeO3/g-C3N4/ZnO, the electrons would be transferred from ZnO and LaFeO3 to g-C3N4. In addition, ·OH plays an important role in photocatalytic reactions for phenol degradation. Thus, the proposed possible photocatalytic reaction mechanism of Z-scheme LaFeO3/g-C3N4/ZnO can provide a more economical and efficient conception for phenol degradation.

Wetting effect of branched anionic Gemini surfactant aqueous solution on PMMA surface.

In this paper, the adsorption behaviour and wetting modification ability of the sodium salts of bis-octadecenoyl succinate (GeminiC3, GeminiC6) and monomers on polymethyl methacrylate (PMMA) surfaces were investigated. The difference in spacer length led to slightly different behaviour of surfactant molecules in solution. The large molecular structure and short flexible spacer of GeminiC3 led to a complex self-aggregation behaviour in solution, forming micelles at low concentrations, leading to a rapid decrease in surface tension and subsequent transition to monolayer or multilayer vesicles. In GeminiC6, the longer flexible spacer groups act as spatial structure modifiers that hinder the formation of vesicles. The adsorption behaviour of the gas-liquid interface was analysed in three stages for the peculiar inflection points where surface tension appears. Combining contact angle measurements, adhesion tension and interfacial tension data showed that GeminiC3 and C6 formed a saturated monolayer on the adsorbed PMMA surface at low concentrations and a bilayer structure at high concentrations. Due to the low resistance of molecular space sites, the monomers adsorbed heavily on the PMMA surface, forming semi-colloidal aggregates with the lowest contact angle of monomeric surfactant solutions reaching 38° on the PMMA surface. Also, the monomer and GeminiC3 and C6 surfactants in this paper have a very high hydrophilic modification ability on the PMMA surface compared to other literature.