摘要
藉XPS,XRD和PZC(零电荷点)方法,研究0.5wt％Pt/CdS表面性质的变化对乙醇水溶液光催化脱氢性能的影响。用光还原法制备的Pt/CdS,经510℃的空气处理,其表面的O/S原子比和PZC都随处理时间的延长而增大(即表面碱性增强),产氢速率(~rH_2)也随之变化。当处理时间为45min时,~rH_2呈现最大值。空气和氩气处理的Pt/CdS样品的X-衍射结果表明。CdS体相六方晶形丰度的增加与其光催化脱氢性能无直接的联系。
The influence of the surface properties of air-treated 0.5 ( wt ) % Pt/CdS on the photocatalytic activity for the dehydrogenation of aqueous ethanol was studied by means of XPS, XRD and PZC. The photo-catalytic activities of 0.5 wt% Pt/CdS for dehydrogenation of ehtanol solution are strikingly changed after treating in air for different periods of time at 510 ℃ and a maximum rH2 was observed after 45 min treatment. With the prolongation of air treatment time the surface O/S atomic ratio and the point of zero charge ( PZC ) increase, indicating that the surface basicity became, higher. As is well known that there are two classes of reactions which can take place on the surface of a photocatalyst: (1)the simple recombination reaction of e- and h+, (2) the photocatalytic redox reaction. During the air treatment, the surface composition of Pt/CdS varies and the change of the densities of surface states, which can exchange electrons with the bulk energy bands, would occur. When the densities of the surface states utilized in the redox reactions reach the maximum or the densities of the surface states utilized in the simple recombination reaction reach the minimum, the maximum rH2 is obtained. The XRD results obtained from the samples treated in air and in Ar showed that the abundance of hexagonal crystalline form in the bulk of CdS increases and which seems to be unrelated to the H2 evolving rate
出处
《分子催化》
EI
CAS
CSCD
1991年第4期340-347,共8页
Journal of Molecular Catalysis(China)
