Strong coupling effect at the interface of cobalt phosphate-carbon dots boost photocatalytic water splitting

Hydrogen and oxygen produced by water splitting under solar energy are ideal future energy sources. At present, obtaining the efficient, stable and inexpensive photocatalyst for photocatalytic overall water splitting is still a huge challenge. Cobalt phosphate (Co₃PO₄, CoPi) possesses proper band positions for water splitting. However, the fast recombination of photogenerated electron and hole pairs for CoPi restricts its application. Herein, strongly coupling Co₃PO₄-carbon dots (CoPi-CDs) composite was constructed as an effective strategy to depress the fast recombination behavior of photogenerated electron and hole pairs. CoPi-CDs show superior photocatalytic water splitting activity than that of single CoPi. When the concentration of CDs in the composite is 0.002 g_CDs/g_catalyst, the hydrogen production rate was obtained for approximately 0.592 μmol h^-1, as well as the oxygen evolution rate about 0.258 μmol h^-1 (with 2:1 stoichiometry), which are both nearly 33 times than that of pristine CoPi. This enhanced photocatalytic activity of CoPi-CDs should ascribe to the efficient coupling effect between CoPi and CDs, which allows fast electron transfer at the interface of CoPi and CDs and thus effectively boosts the photocatalytic water splitting. The strongly coupling nanocomposites should be inspiring for further nanocomposite building for photocatalytic overall water splitting.