Comments on “Interlayer Atomic Voids by Partial Cesium Defect in Layered Titanate Activate Photo(electro)catalytic H2 and O2 Generation”

Üstünel et al. ( ACS Appl. Energy Mater., DOI:10.1021/acsaem.5c01514) recently proposed the interesting concept of interlayer Cs voids formation in lepidocrocite-type Cs2Ti6O13. This was accomplished via treatment of the titanate with an aqueous solution of cetyltrimethylammonium bromide, followed by heat treatment at 700 °C. We present an alternative explanation focusing on: (i) unintended proton exchange from the medium; and (ii) subsequent thermal dehydration/dehydroxylation to anatase and “defective Cs2Ti6O13”. Our interpretation based on the classical chemistry of layered materials is consistent with their experimental results.