Graphdiyne-Promoted Highly Efficient Photocatalytic Activity of Graphdiyne/Silver Phosphate Pickering Emulsion Under Visible-Light Irradiation

As a new kind of two-dimensional carbon allotrope, graphdiyne (GDY) consists of sp- and sp²-hybridized carbon atoms and has recently been used for developing highly efficient photocatalytic systems because of its unique properties. In this study, we find that GDY can form a Pickering emulsion with silver phosphate (Ag₃PO₄) nanoparticles that exhibits largely enhanced photocatalytic activity in the visible-light region. In this system, Ag₃PO₄ acts as a photocatalytically active semiconductor with GDY as the hydrophobic nanostructure. Photocatalytic activity of the Ag₃PO₄/GDY-based Pickering emulsion toward the photodegradation of methylene blue (MB) and photooxidation of water is investigated under visible-light irradiation. Compared to previous Ag₃PO₄/CNT- or Ag₃PO₄/graphene-based Pickering emulsions, the Ag₃PO₄/GDY-based emulsion efficiently catalyzes MB degradation with a higher apparent rate constant k being ∼0.477 min^-1, while for water oxidation its photocatalytic activity is also improved by 1.89 and 1.75 times, respectively. Such an enhancement in the photocatalytic activity is mainly ascribed to the capability of GDY in acting as an acceptor of the photogenerated electrons from Ag₃PO₄ nanoparticles and in facilitating the hole transportation as well as in reducing Ag⁺ to Ag⁰. This study demonstrates that GDY is a new candidate with a promising future in developing photocatalytic systems with high efficiency for real applications.