Effects of Calcination Temperature on the Physical Properties and Hydrogen Evolution Activities of La5Ti2Cu(S1‐xSex)5O7 Photocatalysts

Abstract

AbstractLa5Ti2Cu(S1‐xSex)5O7 (LTCS1‐xSexO) solid solutions are found to function as visible‐light‐driven photocatalysts to evolve H2 from aqueous solutions containing sacrificial electron donors. However, this photocatalytic activity is reduced with increasing Se concentrations because of excessive particle growth during calcination at high temperatures. In the present study, the physical properties and photocatalytic H2 evolution activities of LTCS1‐xSexO (0 ≤ x ≤ 0.6) solid solution photocatalysts synthesized by solid‐state reactions at varying temperatures are assessed. It is found that the photocatalyst particle sizes are reduced upon lowering the calcination temperature. In addition, the calcination temperature resulting in the highest photocatalytic H2 evolution rates for NiS‐loaded LTCS1‐xSexO is shown to become lower with increasing Se content. The H2 evolution activity of LTCS1‐xSexO (0.2 ≤ x ≤ 0.6) is improved several‐fold by optimizing the calcination temperature because the excessive growth of particles is avoided. The activity of these materials is further improved by coloading Pt and NiS cocatalysts. This work demonstrates the importance of controlling the particle size of narrow bandgap LTCS1‐xSexO oxysulfoselenides so as to effectively utilize visible light during photocatalytic H2 evolution.