Photo-Chemical Energy Conversion by Pillared Hydrotalcite

通过Cd(edta)^<2->和S^<2->的化学反应，将CdS和CdS- zns混合半导体颗粒掺入水滑石夹层中。掺入的颗粒似乎很小，厚度小于0.4 nm。cd和层间ZnS顺序析出cd的带隙能略大于普通晶体cd的带隙能。另一方面，cd /ZnS混合物在层间共析出的带隙能几乎等于正晶cd和ZnS的带隙能的平均值。在Na_2S和/或Na_2SO_3作为牺牲供体存在的情况下，CdS和CdS/ZnS混合物在可见光照射下能够高效析氢。在水滑石中掺入催化剂的产氢活性依次为：先析出CdS，后析出ZnS >，同时析出CdS-ZnS混合物>> CdS。产物通过中间层的传质问题限制了水滑石中半导体在可见光诱导析氢中的效率。SO_3^<2->水溶液与未负载的CdS/ZnS光化学氧化反应生成的S_2O_6^<2->和SO_4^<2->的量基本相同，但与cd /ZnS掺入水滑石反应生成的S_2O_6^<2->的量明显减少。

CdS and CdS-ZnS mixed semiconductor particles were incorporated into the interlayer of hydrotalcite by the chemical reactions between Cd(edta)^<2-> and S^<2-> in the interlayer. The incorporated particles seemed to be small as less than 0.4 nm in thickness. The band gap energies of CdS and sequentially precipitated CdS followed by ZnS in the interlayer were slightly larger than that of normal-crystalline CdS. On the other hand, the band gap energy of CdS/ZnS mixture coprecipitated in the interlayer was almost equal to the average value of those of normal-crystalline CdS and ZnS. The CdS and CdS/ZnS mixture incorporated into hydrotalcite were capable of efficient hydrogen evolution by irradiation with visible light in the presence of Na_2S and/or Na_2SO_3 as a sacrificial donor. The hydrogen production activities of the catalyst incorporated in hydrotalcite were in the order of sequentially precipitated CdS followed by ZnS > simultaneously precipitated CdS-ZnS mixture >> CdS. Mass transfer problems of the products through the interlayer restricted the efficiency of the semiconductor incorporated into hydrotalcite for the visible light induced hydrogen evolution. Almost the same amounts of S_2O_6^<2-> and SO_4^<2-> were formed by the photochemical oxidation of SO_3^<2-> aqueous solution with unsupported CdS/ZnS, but that of S_2O_6^<2-> produced in the same reaction with CdS/ZnS incorporated into hydrotalcite significantly decreased.