For photocatalytic water splitting rate enhancement, it is said efficient to add oxidizing sacrifice agents to water, which can consume produced O
2, in order to repress the reverse reaction,
i.e. re-coupling of produced H
2 and O
2. From the viewpoint of carbon-neutral taking photosynthesis in nature into account, saccharides of foodstuffs are selected as experiementing oxidizing sacrifice agents. Additionally, a pyroligneous acid is also adopted as one of candidates of nonfood oxidizing sacrifice agents together with an acetic acid of its main component as a reference chemical. Since the most promising photocatalyst for water splitting is TiO
2, that is clear from its electronic band structure, three commercial TiO
2 are utilized after loading Pt. A simple batch vessel is employed as an apparatus since the purposes of this study are to clarify the fundamental characteristics of photocatalytic H
2 production and to optimize the operating conditions. As the results, 0.10 wt%-Pt loaded P25 is realized to provide the highest H
2 producing rate of 2.60
l/(m
2 · h) from 50 g/
l glucose aqueous solution. Though slightly higher efficiency can be obtained by regulating pH value, above-mentioned operating conditions with free pH are concluded superior from the viewpoint of consuming chemical for intending pH to efficiency increment. On the contrary to similar high photocatalytic H
2 producing rates from solutions of monosaccharide (glucose and fructose) and disaccharide (sucrose), solution of polysaccharide (starch) shows remarkably slow H
2 producing rate down to one-eighth of prescribed ones from monosaccharide and disaccharide, resulting in necessity of pretreating such macromolecules to unimolecules and/or micromolecules, controlling their adsorption to photocatalyst in order to adopt them as oxidizing sacrifice agents. A remarkably low H
2 producing rate is recognized from a solution of nonfood pyroligneous acid. Therefore, searches for other natural oxidizing sacrifice agents remain as an indispensable future task.
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