Enhanced photocatalytic H₂-production activity of bicomponent NiO/TiO₂ composite nanofibers.

Hydrogen has been regarded as an ideal candidate for the replacement of conventional fossil fuels due to its environmental friendliness and recycling possibility. In this work, mesoporous NiO/TiO2 bicomponent composite nanofibers were prepared by a electrospinning and calcination method. The H2-production activity of the prepared samples was examined by water splitting using methanol as scavenger under simulated solar Xenon lamp irradiation. The effect of NiO loading on the microstructure and photocatalytic H2-production activity of NiO/TiO2 composite samples was studied and discussed. The results demonstrated that the presence of a small amount of NiO obviously inhibited the growth of TiO2 crystallites. With increasing the NiO content, the average crystallite size further decreased. In contrast, the Brunauer-Emmett-Teller (BET) specific surface areas, pore volumes and average pore size steadily increased. Photocatalytic H2-production experiment confirmed that NiO was an efficient co-catalyst for the photocatalytic H2 production of TiO2. The optimal NiO loading was determined to be 0.25 wt.%, giving a H2-production rate of 337 μmol h(-1) g(-1) with apparent quantum efficiency (QE) of 1.7%, which exceeded the rate on pure TiO2 by more than 7 times. The enhanced H2-production activity was due to the deposition of NiO clusters on the surface of TiO2, which suppressed the recombination of photogenerated electron-hole pairs, reduced the overpotential of hydrogen production and catalyzed production of hydrogen. This work showed that low-cost and earth-abundant NiO could be used as co-catalyst for photocatalytic hydrogen production.