光催化技术被认为是最有前景的环境污染处理技术,这就使得光催化剂材料备受瞩目.近年来,铁电材料作为新型光催化剂材料受到人们越来越多的关注,其原因在于铁电材料特有的自发极化有望解决催化反应过程中的电子-空穴对复合问题,进而提高光催化活性.本文从两个方面对铁电极化如何影响光催化进行综述:一方面,从铁电极化入手归纳总结其对电子-空穴对分离的影响,进而更深入地从极化引发的退极化场和能带弯曲两个部分来阐述具体的影响机理;另一方面,为了消除静电屏蔽,分别从温度、应力(应变)、电场三个外场因素调控极化入手,归纳总结外场调控极化对电子-空穴对分离的影响,进而影响光催化活性.最后对该领域今后的发展前景进行了展望.
Photocatalytic technology is considered to be the most promising treatment technology of environmental pollution.In this technology, the electronhole pairs generated by the light-responsive materials under sunlight irradiation will produce the oxidation-reduction reactions with the outside world. At present, there are still a series of problems needed to be solved in the photocatalytic technology, among which the recombination of photogenerated electron-hole pairs is a very important limitation. In recent years, the ferroelectric materials have attracted much attention as a new type of photocatalyst because the spontaneous polarizations of ferroelectric materials are expected to solve the recombination problem of electronhole pairs in the catalytic reaction process. However, there are no systematic analyses of the specific mechanisms for ferroelectric materials. In this paper, we review the effects of ferroelectric polarization of ferroelectric materials on photocatalytic activity from three aspects. Firstly, the polarization can give rise to depolarization field and band bending, thereby affecting the separation rate of electron-hole pairs, and speeding up the transmission rate.Therefore, in the first part, the effects of depolarization field and energy band bending on catalytic activity are summarized. This can conduce to understanding the influence of polarization on catalytic activity more clearly from the intrinsic mechanism. Next, the built-in electric field induced by the polarization of ferroelectric material can increase the separation rate of photogenerated carriers and improve the catalytic activity. However, the static built-in electric field easily leads to free carrier saturation due to the electrostatic shielding, which reduces the carrier separation rate. Thus,in order to eliminate the electrostatic shielding, the effects of three external field including temperature, stress(strain)and electric field, which can regulate polarization, on the separation of electronhole pairs and photocatalytic a