Synergistic Cocatalytic Effect of Carbon Nanodots and Co3 O4 Nanoclusters for the Photoelectrochemical Water Oxidation on Hematite.

Cocatalysis plays an important role in enhancing the activity of semiconductor photocatalysts for solar water splitting. Compared to a single cocatalyst configuration, a cocatalytic system consisting of multiple components with different functions may realize outstanding enhancement through their interactions, yet limited research has been reported. Herein we describe the synergistic cocatalytic effect between carbon nanodots (CDots) and Co3 O4 , which promotes the photoelectrochemical water oxidation activity of the Fe2 O3 photoanode with a 60 mV cathodically shifted onset potential. The C/Co3 O4 -Fe2 O3 photoanode exhibits a photocurrent density of 1.48 mA cm(-2) at 1.23 V (vs. reversible hydrogen electrode), 78 % higher than that of the bare Fe2 O3 photoanode. The slow reaction process on the single Co(III) -OH site of the Co3 O4 cocatalyst, oxidizing H2 O to H2 O2 with two photogenerated holes, could be accelerated by the timely H2 O2 oxidation to O2 catalyzed on CDots.