“…This is illustrated in the several of the references discussed above, with inhibition increasing at RH levels at which either a fully chemisorbed layer of water is established or at which physisorbed layers become stable. Examples of photooxidation studies on TiO 2 in which authors observed chemisorbed water acting as a site blocker include: CO [783], formaldehyde [1316], methanol [714], ethanol [890,897], acetaldehyde [1321], acetone [752,1026], ethylene [738,1322], 1-butene [1313,1314], butadiene [1311], toluene [941,943], and trichloroethylene [1006,1315]. As an example, Fig.…”