Study of Surface Acid-Base Properties Of Gas-Sensitive Metal Oxides

Binary (ZnO, Fe
₂
O
₃
) and ternary (ZnFe
₂
O
₄
) gas-sensitive oxide materials are synthesized, and the correlation between their sensitivity to ethanol vapors and the functional chemical composition of the surface is studied by X-ray photoelectron spectroscopy and adsorption of acid-base indicators. It is found that the sensitivity to ethanol vapors increases with increasing acid sites with pK
_a
= 2.5 and with increasing percentage of surface oxygen of OH/CO
₃
/C-O groups. This correlation is caused by the specific interaction between ethanol molecules and hydroxyl groups on the surface of the oxides.