Photocatalytic water splitting is a sustainable platform that can address the ever growing global energy demands and environmental concerns. Ta3N5 highlights an intriguing paradigm for photocatalytic water splitting owing to its narrow bandgap to absorb visible light; however, pristine Ta3N5 is still far from its theoretical performance due to the defects originating from ammonolysis. However, enhanced performance of Ta3N5 was observed by aliovalent cation substitution. Mg2+(72 pm) is a potential dopant for Ta5+(64 pm) due to similar ionic radii. Its substitution for Ta5+ causes replacement of some of the N3- by O2- to maintain the charge balance, creating an oxynitride, MgxTa3-xO3xN5-3x. This Mg introduction also promotes electron migrations in the photocatalyst, leading to enhanced catalytic activity. Typically, irregular morphologies of Mg doped Ta3N5 will result through the conventional synthetic techniques, which in turn limits performance. Ultrasonic spray synthesis (USS) provides a facile route toward complex metal oxides as a fine powder composed of microspheres, which can potentially be converted to oxynitrides with preservation of the microsphere morphology. Here, Ta-O microspheres with different levels of Mg doping are achieved via USS. These particles then serve as precursors, yielding porous microspheres of MgxTa3-xO3xN5-3x with nitridation. The synthesis and characterization of MgxTa3-xO3xN5-3x are presented herein, with future plans outlined.

Toward Mg-doped tantalum oxynitrides for photocatalysis: Aerosol synthesis of oxide precursors with tunable dopant content

2019 Spring National Meeting

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