Photocatalytic H 2 production on TiO 2 with tuned phase structure via controlling the phase transformation

A series of TiO 2 samples were prepared from the precursor P25 using impregnation method followed by a calcination. The phase compositions of the samples were controlled by addition of various additives, including NaNO 3 , NaHCO 3 , Na 2 SO 4 , Na 3 PO 4 , Na 2 SiO 3 , and Na 2 MoO 4 . X-ray diffraction patterns demonstrate that the phase transformation from anatase to rutile can be suppressed to a different extent by these additives. Photocatalytic H 2 production reactions were performed in methanol aqueous solution. The catalysts, with the addition of NaNO 3 , NaHCO 3 , and Na 2 SO 4 , show a great improvement in the H 2 production activity, while others show a negative effect. This indicates that both the phase structure and the properties of the additives are important for the photocatalytic activity. Infrared spectra of pyridine adsorption on the catalysts reveal that the decreased acidity of the samples may be responsible for the suppressed CO production in the photocatalytic methanol reforming.