Nickel-loaded nitrogen-doped titanate nanostructured catalysts for solar-light driven hydrogen evolution and environmental remediation

Abstract

In this work hydrogen production activity of a series of the nickel-loaded, nitrogen-doped titanate-based photocatalysts was tested by water splitting reaction in isopropanol-water mixture. The utilization of ammonium ions during catalyst synthesis and subsequent calcination led to successful formation of nitrogen-doped nanotubular titanates with lower sodium content, favored titanate-to-anatase transformation and enhanced textural, morphological and interface properties. The photocatalytic tests revealed that hydrogen production activity of nitrogen-doped titanates is ten times higher compared to nitrogen-free titanates. The presence of highly photoactive anatase phase, improved anatase crystallinity and lower amount of sodium ions are found to be decisive factors for increased hydrogen production activity. The optimal nickel loading was determined and the variation in photocatalytic activity with reduction temperature was explained. Stability tests gave quantitative analysis of the effects of reaction products accumulation and photocorrosion on the catalyst deactivation.