Realizing selective water splitting hydrogen/oxygen evolution on ferroelectric Bi3TiNbO9 nanosheets

Water splitting hydrogen-oxygen evolution is the most promising way to solve the current energy crisis. Realizing the selective generation of hydrogen and oxygen via water splitting in a single photocatalyst is significant but still a challenge. Herein a layered ferroelectric material Bi3TiNbO9 was synthesized by a modified molten-salt method and solid state method. The exposed facets of the nanosheets synthesized with the modified molten-salt method were {001} and {110}, and the ratio of which can be well-tuned by adjusting the synthesis temperature. Bi3TiNbO9 nanosheets present both hydrogen and oxygen evolution via water splitting under illumination, and the hydrogen generation or oxygen generation can be selectively optimized by simply adjusting the ratio value of {001}/{110} exposed facets. The as-prepared samples with the highest {001} exposed facet displayed the highest hydrogen evolution activity (342.6 μmol h−1g−1), while the samples with the highest {110} exposed facet showed the highest oxygen evolution activity (275.2 μmol h−1g−1), indicating that the {001} and {110} facets of the Bi3TiNbO9 were the active hydrogen generating facet and the active oxygen generating facet respectively. This research is very instructive in the rational design of highly efficient hydrogen generation or oxygen generation respectively in the similar photocatalyst.