SrTiO3 catalysts prepared from topochemical conversion of Bi4Ti3O12 nanoplatelets: Surface characterizations and interactions with isopropanol

The heterostructural Bi4Ti3O12-SrTiO3 (or BIT-STO) platelets with various STO contents (i.e., 40, 65, and 100%) were synthesized by the topochemical conversion of well-defined BIT platelets via the alkaline hydrothermal treatment. The surface properties of synthesized BIT-STO platelets were characterized, and probed by the temperature-programmed surface reaction of isopropanol (IPA). It is found that all BIT-STO catalysts are highly selective in IPA dehydrogenation (to yield acetone) as opposed to IPA dehydration (to yield propene). With the increase in STO content, the desorption temperature of acetone from the BIT-STO surface gradually decreases, suggestive of an improved IPA dehydrogenation activity. The BIT-derived STO exhibits much higher activity and selectivity in IPA dehydrogenation in comparison to the hydrothermally-synthesized STO and commercial STO, which is attributed to the desirable (100) facet with abundant surface defects formed during the topochemical conversion. In-situ infrared spectroscopy indicates that upon IPA adsorption, the BIT-derived STO shows a higher proportion of bridged isopropoxide (IPO) presents on the surface than the reference STO samples. It is proposed that the abundant oxygen vacancies present on the surface of BIT-derived STO could facilitate the bridged adsorption of IPO intermediate that favors further decomposition into acetone, thus promoting the selective IPA dehydrogenation.