CoP decorated with Co3O4 as a cocatalyst for enhanced photocatalytic hydrogen evolution via dye sensitization

• Published in: Applied surface science 2019-09, Vol.487, p.315-321
• Main Authors: Peng, Shaoqin, Cao, Yang, Zhou, Fengxian, Xu, Zhaodi, Li, Yuexiang
• Format: Article
• Language: English
• Subjects: Cocatalyst; CoP/Co3O4 composite; Dye sensitization; H2 evolution; Visible light
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2019.05.113

Developing effective, stable and cheap hydrogen evolution reaction (HER) cocatalysts have attracted great interest. Herein, noble-metal-free cocatalyst CoP/Co3O4 composite is synthesized via a simple low temperature (300 °C) solid phosphidation reaction using cobalt hydroxide and sodium hypophosphite. The composition, structure, morphology and photoabsorption performance of the as-prepared samples are characterized by XPS, XRD, TEM, UV–Vis DRS and PL technologies. As a HER cocatalyst, the photocatalytic hydrogen evolution activity of CoP/Co3O4 using EY dye as a sensitizer and trimethylamine (TMA) as an electron donor is investigated under visible light irradiation (λ ≥ 420 nm). The result shows that CoP/Co3O4 composite exhibits excellent photocatalytic H2 evolution activity and good stability. The highest apparent quantum yield (AQY) reaches 40.5% under the optimal conditions. The presence of Co3O4 decorated on CoP can promote H2O dissociation in the alkaline medium and decrease the HER overpotential, therefore, the activity of CoP/Co3O4 composite for the H2 evolution is higher than CoP alone. [Display omitted] •CoP decorated with Co3O4 composite is synthesized via a solid phosphidation reaction.•CoP/Co3O4 composite exhibits high dye-sensitized photocatalytic hydrogen evolution activity.•Co3O4 enhances the activity via promoting water dissociation into proton in alkaline medium.•The AQY of 40.5% at 420 nm is achieved under the optimized conditions.