Photo-induced in-situ synthesis of Cu₂O@C nanocomposite for efficient photocatalytic evolution of hydrogen

Cuprous oxide (Cu₂O) is an ideal visible light catalyst owing to its narrow band gap, environmental benignity and abundant storage; however, the fast recombination of photogenerated charge carriers and poor stability of Cu₂O has impeded its application in photocatalysis. Herein, we demonstrate that Cu₂O@C nanocomposite can spontaneously evolve from a methanol aqueous solution containing cupric ions under the induction of irradiation. Compared with the traditional carbon coating method, the Cu₂O@C nanocomposite obtained by the photo-induced in-situ synthesis can reserve superior original characteristics of the semiconductor under mild reaction conditions, promote the charge transfer and enhance the separation efficiency of charge carriers; in addition, the carbon shells can also effectively prevent Cu₂O from photo-corrosion. As a result, the Cu₂O@C nanocomposite exhibits excellent photocatalytic activity in the hydrogen evolution in comparison with the Cu₂O particles; the H₂ evolution rate over the Cu₂O@C nanocomposite reaches 1.28 mmol/(g·h) under visible light, compared with the value of 0.065 mmol/(g·h) over Cu₂O. Moreover, the Cu₂O@C nanocomposite displays good cycle stability, viz., without any deactivation in the catalytic activity after five cycles.