Bi@H-TiO2/B-C3N4 heterostructure for enhanced photocatalytic hydrogen generation activity under visible light

Abstract

Herein, a ternary Bi@H-TiO2/B-C3N4 type II heterostructure is successfully designed and prepared via metal Bi as cocatalyst for photocatalytic H2 generation. As expected, under λ > 300 nm light, the highest photocatalytic hydrogen production rate (HPR) of Bi@H-TiO2/B-C3N4 is up to 223.08 μmol g−1 h−1. Excitingly, under visible light (λ > 400 nm), the highest HPR of Bi@H-TiO2/B-C3N4 is increased to 18.84 μmol g−1 h−1, which is about 67.3 times, 37.7 times and 6.8 times as high as that of H-TiO2, B-C3N4 and H-TiO2/B-C3N4 under the same conditions, respectively. Moreover, the electrochemical impedance spectroscopy and transient photocurrent tests manifest that the interface resistance of Bi@H-TiO2/B-C3N4 composite decreases and the photocurrent density increases after loading metal Bi. These results indicate that loading metal Bi as cocatalyst (providing more electron trapping sites) is beneficial to improve photocatalytic activity in the type II heterostructure composite. And the electron transfer directions (B-C3N4 → H-TiO2 → Bi or B-C3N4 → Bi) are proved by ultraviolet photoelectron spectroscopy test. Therefore, the Bi@H-TiO2/B-C3N4 photocatalyst with strong visible light absorption is expected to be a promising candidate in photocatalytic fields under visible light.