Penta-BCN monolayer: a metal-free photocatalyst with a high carrier mobility for water splitting.

Photocatalytic water splitting has been regarded as a promising strategy to provide clean energy and solve the energy crisis; thus, extensive efforts have been devoted to developing highly efficient photocatalysts. Herein, based on density functional theory computations, we demonstrated that the penta-BCN monolayer is a promising photocatalyst for water splitting. The penta-BCN monolayer is semiconducting with a moderate direct band gap of 2.87 eV, and its band edge positions straddle the redox potentials of water. Remarkably, the penta-BCN monolayer also has a pronounced optical absorption in the ultraviolet and visible light regions and exhibits an ultrahigh hole mobility (∼2 × 10 5 cm 2 V -1 s -1 ). These desirable properties render the penta-BCN monolayer a promising candidate for photocatalytic water splitting.