A facile mechanochemical route to a covalently bonded graphitic carbon nitride (g-CN) and fullerene hybrid toward enhanced visible light photocatalytic hydrogen production.

Graphitic carbon nitride (g-CN) as an emerging two-dimensional (2D) nanomaterial has been commonly used as a metal-free photocatalyst with potential applications in visible light photocatalytic water-splitting. However, the photocatalytic activity of g-CN is quite low due to its relatively large band gap and the existence of contact resistance between the nanosheets. Herein we report for the first time the facile synthesis of a covalently bonded g-CN/C hybrid via a solid-state mechanochemical route and its application in photocatalytic hydrogen production under visible light. The g-CN/C hybrid was synthesized by ball-milling g-CN and C in the presence of lithium hydroxide (LiOH) as a catalyst. The hybrid nature and conformation of the g-CN/C hybrid were confirmed by a series of spectroscopic and morphological studies, featuring the covalent bonding of C onto the edges of g-CN nanosheets via a four-membered ring of azetidine, which has never been reported in fullerene chemistry. The g-CN/C hybrid was further applied to metal-free visible light photocatalytic hydrogen production, affording a H production rate of 266 μmol h g without using any noble metal cocatalyst such as Pt, which is about 4.0 times higher than that obtained for the pristine g-CN photocatalyst.