Heterostructure of Ta3N5 nanorods and CaTaO2N nanosheets fabricated using a precursor template to boost water splitting under visible light

Fabrication of heterostructure composed of one-dimensional (1D) and 2D semiconductors has inspired extensive interest in promoting photogenerated charge separation as well as performances of solar fuel production, but it is still challenging for (oxy)nitride photocatalysts due to their uncontrollable ammonia thermal preparative process. In this work, we report a synthesis on heterostructure of Ta3N5 nanorods and CaTaO2N (CTON) nanosheets (denoted as Ta3N5/CTON) by directly nitriding a 2D Dion-Jacobson (DJ) type of perovskite KCa2Ta3O10 (KCTO) precursor under the assistance of K2CO3 flux. It is demonstrated that the 2D morphology of KCTO can be well inherited to get 2D CTON, and the Ta-rich (non-stoichiometric ratio of Ca:Ta compared to CTON) feature of the KCTO as well as the easy evaporation of K species results in the formation of 1D Ta3N5 nanorods. Meanwhile, the formation of intermediate species K2Ca2Ta3O9N owning similar crystal lattice as Ta3N5 was detected and deduced to be responsible for the generation of Ta3N5 nanorods and observation of intimate interface between CTON and Ta3N5. Benefitting from the formation of special 1D/2D type-II heterostructure, obviously promoted charge separation as well as photocatalytic water splitting performance can be obtained. Extended discussion demonstrates the generality of the hard-template preparative strategy developed here. To our knowledge, this should be the first fabrication of 1D/2D heterostructure for the (oxy)nitride semiconductors, and the developed hard-template strategy may provide an alternative way of fabricating heterostructures of other semiconductors prepared at high temperature.