Controllable synthesis of Co nanoparticles with the assistance of cucurbit[6]uril and its efficient photoelectrochemical catalysis in water splitting on a g-C3N4 photoanode

Photoelectrochemical water splitting based on g-C3N4 is considered as a promising approach to oxygen generation. Hereinto, an innovative photoanode, g-C3N4/Q[6]–Co NPs, is successfully fabricated by depositing a Co nanocatalyst on the surface of a g-C3N4 film. The nanoparticles are prepared by reduction of a coordination compound of Co[II]–cucurbit[6]uril, in which the macrocycle served as a template and supporter. The resulting g-C3N4/Q[6]–Co NPs provided a significant improvement of the photocurrent density (393 μA cm−2 at 1.23 V vs. RHE) and a higher photoconversion efficiency (0.02419%) than the pristine g-C3N4 catalyst. These results reveal that the high visible light absorption of g-C3N4/Q[6]–Co NPs ensures the formation of a large number of photogenerated electron–hole pairs, and therefore the holes are immediately transferred to the g-C3N4 film through the semiconductor–metal interface, inhibiting the charge recombination process and increasing the photocurrent performance. The approach proposed in this study not only provides a new strategy, in which a macrocyclic compound is employed as the template and supporter in the synthetic process of the nanocatalyst, but also opens a new window for the application of g-C3N4 in PEC water splitting.