Positive Ni(HCO₃)₂ as a Novel Cocatalyst for Boosting the Photocatalytic Hydrogen Evolution Capability of Mesoporous TiO₂ Nanocrystals

Abstract

A highly efficient hybrid photocatalytic system consisting of Ni(HCO3)2 and mesoporous TiO2 microrods was successfully fabricated by a hydrothermal approach. The involvement of Ni(HCO3)2 cocatalyst resulted in significant improvement of the hydrogen evolution on the host TiO2 photocatalyst under artificial sunlight irradiation. The optimized hybrid photocatalysis system with 2.5% (mole ratio) Ni(HCO3)2 loading displayed the highest hydrogen evolution rate of 1798.0 μmol g–1 h–1, which was more than 18 times higher than that of pure mesoporous TiO2. On the basis of the photoluminescence spectroscopy and photoelectrochemical measurement results, it is proposed that the enhancement of photocatalytic hydrogen evolution capability on the TiO2–Ni(HCO3)2 host photocatalyst–cocatalyst is not only attributed to the efficient separation of photoinduced electron–hole pairs, but also derived from the Ni(HCO3)2 cocatalyst acting as active reaction sites toward hydrogen production.