Fabrication of TiO(2) on porous g-C(3)N(4) by ALD for improved solar-driven hydrogen evolution

Porous graphitic carbon nitride (P-g-C(3)N(4)) thin sheets were fabricated by a one-step calcination of a mixture of urea, melamine, and ammonia chloride at 550 °C. P-g-C(3)N(4) showed 48% higher photocatalytic H(2) production from methanol aqueous solution than conventional urea-derived graphitic carbon nitride (g-C(3)N(4)) because the existence of numerous pores reduces the recombination rate of charge carriers. In order to further enhance the photocatalytic activity, TiO(2) was uniformly deposited on P-g-C(3)N(4) by 60–300 cycles of atomic layer deposition (ALD) to form the TiO(2)@P-g-C(3)N(4) composite. They exhibited much higher photocatalytic hydrogen production rates than both TiO(2) and P-g-C(3)N(4). Among all composites, the sample deposited with 180 ALD cycles of TiO(2) showed the highest H(2) production because of optimal diffusion length for electrons and holes. It also performed better than the sample of g-C(3)N(4) deposited with 180 cycles of TiO(2).