Insights into the structural, and functionality of RuO2/TiO2 and Ni(OH)2/RuO2/TiO2 for water splitting and dye degradation

Abstract

Heterogeneous catalysis and the uniform interface are playing a vital role in environmental protection and are amenable to photoelectrochemical transformation reactions. Herein, a mixed metal oxide catalyst composed of RuO2 or RuO2/Ni(OH)2 supported on TiO2 is developed via the facile sol-gel method. Structural and morphological analyses confirm the presence of RuO2 and Ni(OH)2 beside the anatase phase in the composite catalysts . The band gap of TiO2 is tuned after contacting with RuO2 (2.35 eV) and the surface area is doubled. XPS shows the existence of a high level of defects and VSM demonstrates a ferromagnetic-like hysteresis loop for TiRu. A fast positron annihilation is observed of TiRu compared to TiO2 indicating smaller free volume defects in the composite powders. The oxidation tests of water display a high current density of 18.6 mA/cm2 and dimensional stability for the TiRu sample with negligible electroactivity for TiRuNi. On the other hand, the photoelectrochemical water splitting activity is found to be the lowest for the composite samples compared to TiO2. The photocatalytic efficiency is further examined via the removal of two industrial dyes (Dianix Blue and Indigo Carmine dyes) and the performance is correlated to the results obtained from Mott-Schottky.