Nanodiamond-Embedded p-Type Copper(I) Oxide Nanocrystals for Broad-Spectrum Photocatalytic Hydrogen Evolution

Copper(I) oxide (Cu2O) is an attractive photocatalyst because of its abundance, low toxicity, environmental compatibility, and narrow direct band gap, which allows efficient light harvesting. However, Cu2O exhibits poor photocatalytic performance and photostability because of its short electron diffusion length and low hole mobility. Here, it is demonstrated that nanodiamond (ND) can greatly improve the photocatalytic hydrogen evolution reaction (HER) of the p-type photocatalyst Cu2O nanocrystals by nanocomposition. Compared with pure Cu2O nanocrystals, this composite shows a tremendous improvement in HER performance and photostability. HER rates of 100.0 mg NDs-Cu2O nanocrystals are 1597 and 824 under the simulated solar light irradiation (AM 1.5, 100 mW cm(-2)) and visible light irradiation (420-760 nm, 77.5 mW cm(-2)), respectively. The solar-to-hydrogen conversion efficiency of this composite is 0.85%, which is nearly ten times higher than that of pure Cu2O. The quantum efficiency of the composite is high, with values of 0.17% at and 0.23% at . The broad spectral response of ND provides numerous carriers for the subsequent reactions. The electron-donating ability of ND and suitable band structures of the two components promote electron injection from ND to Cu2O. These results suggest the broad applicability of ND to ameliorate the photoelectric properties of semiconductors.