A green approach: scalable dry media synthesis of a γ-TaON photocatalyst for solar H2 production and rhodamine B degradation

Abstract

Extending the light absorption range and facilitating the separation of photo-induced charge carriers are effective strategies to improve the performance of the photocatalytic process. Here, we report a new, scalable and low temperature solid state method for the synthesis of different TaON polymorphs. Tantalum oxynitride (TaON), a visible light active photocatalyst, was investigated for photocatalytic H₂ production as well as degradation of Rhodamine B under artificial solar light (Xe lamp) and natural sunlight. XPS confirms substitutional (N_s) as well as interstitial (N_i) nitrogen incorporation into the Ta₂O₅ lattice. Optical characterization reveals a red shift in absorption from the UV to visible region for TaON samples. XRD confirms the crystalline phase of different polymorphs of TaON such as γ, β etc. The results of the photocatalytic activity of the synthesized catalysts for hydrogen (H₂) production via H₂O splitting and degradation of the Rhodamine B pollutant show that among the series of synthesized catalysts, the pure γ-TaON phase displays the highest H₂ production of 1393.6 μmol per 0.1 g per hour under natural solar light, whereas under similar experimental conditions 833.6 μmol per 0.1 g hour under a xenon lamp using triethanolamine as a sacrificial electron donor is observed. Likewise, the synthesized γ-TaON photocatalyst decomposes 99.8% of 10 ppm Rhodamine B solution in just 100 min under natural solar light.