During H2 production photocatalytically P-25 TiO2 gives almost 3 times more hydrogen than pure anatase Hombikat TiO2 having a surface area of 300 m2/g as compared to 50 m2/g for P-25.
Even surface area & having pure phase its yield is much lower during production what other factors like crytallite size pore Volume Pore diameter etc is more prominent play a role and P-25 is mixed is that a synergistic effect of both phase?? which is more dominant?
Herr Salz, Sie haben recht.
To my way of thinking, combination of rutile and anatase found in P-25 (Evonik) results in increase of photocatalytic properties - it's a matter of general experience, you know. Furthermore, you'd better compare the crystallites' sizes of both materials studied. The bigger size is, the higher is the efficiency of TiO2-based photocatalysts. SBET must be taken into account only under consideration of ks, i.e. when photocatalytic activity is evaluated via relation of k1(first-order reaction constant) to m2/g of a photocatalyst used. In your case, SBET is not of essential importance because there's no adsorption process occurring in the course of hydrogen production.
Your welcome!
but more surface area more active sites can be possible so where it is lacking
Nope. It's not important provided there are even more sites which are less active than more active ones located on smaller area. You have to focus on the character of the sites before their quantity would be discussed.
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