Preparation of Ba1-xSrxTiO3 by the sol-gel assisted solid phase method: Study on its formation mechanism and photocatalytic hydrogen production performance

To explore the formation mechanism of barium strontium titanate (Ba1-xSrxTiO3, BST) in a heat treatment process and the effect of the Ba/Sr proportion on the microstructure and photocatalytic activity of Ba1-xSrxTiO3, a series of Ba1-xSrxTiO3 samples were synthesized by the sol-gel assisted solid phase method. A reaction mechanism model of Ba0.7Sr0.3TiO3 was established, and the nucleation and growth processes during the heat treatment process were determined. It was found that the lattice constant of BST linearly increased as the Ba content increased. The crystal size of Ba1-xSrxTiO3 increased with an increasing Ba content, but when Ba:Sr = 7:3, it was observed that the grain size was 250 nm, which was a smaller value than that of Ba0.6Sr0.4TiO3. In terms of photocatalytic performance, it was found that with an increasing Ba content, the carrier recombination rate gradually increased. However, when Ba:Sr = 7:3, the band gap of BST was the smallest (Eg = 3.027 eV) and had the largest photocatalytic hydrogen production rate (92.05 μmol/g/h).