直接Z型LaNiO_(3)/Mn_(0.2)Cd_(0.8)S异质结催化剂光解水产氢性能及机理探究

Direct Z-Scheme LaNiO_(3)/Mn_(0.2)Cd_(0.8)S Heterojunction Photocatalysts:Enhanced Photocatalytic Performance for H Evolution and Investigation of Mechanism

以LaNiO_(3)纳米颗粒为基质,在水热法制备CdS的过程中引入Mn2+离子,原位合成直接Z型LaNiO_(3)/Mn_(0.2)Cd_(0.8)S异质结光催化剂。分别采用场发射扫描电镜、X射线衍射、X射线光电子能谱、紫外可见漫反射光谱、氮气吸附-脱附测试以及电化学测试等分析方法对制备的催化剂进行表征。在光解水产氢测试中,LaNiO_(3)/Mn_(0.2)Cd_(0.8)S异质结光催化剂在5 h的H_(2)产量达到1 190.3μmol,相较于CdS和Mn_(0.2)Cd_(0.8)S,其H_(2)产量分别提高了 25倍和10倍。荧光和电化学实验证实,Mn2+的引入能够有效地促进光生载流子的分离,同时LaNiO_(3)/Mn_(0.2)Cd_(0.8)S之间异质结的构筑能有效地促进光生载流子在界面间的迁移、分离,从而促进其光解水产氢效率和稳定性的提高。结合一系列表征和活性测试结果提出直接Z型光解水反应机理,很好地阐述了其光解水产氢活性和稳定性的增强。

Direct Z-scheme LaNiO_(3)/Mn_(0.2)Cd_(0.8)S heterojunction photocatalysts were synthesized in situ by the introduction of Mn2+ ions in the hydrothermal preparation of CdS using LaNiO_(3) nanoparticles matrix and fully characterized by field emission scanning electron microscope,powder X-ray diffraction,X-ray photoelectron spectroscopy,UV-Vis diffuse reflectance spectra,N2 adsorption-desorotion test and electrochemistry test.LaNiO_(3)/Mn_(0.2)Cd_(0.8)S heterojunction photocatalysts showed improved photocatalytic H_(2) evolution and stability.The photocatalytic H_(2) evolution over LaNiO_(3)/Mn_(0.2)Cd_(0.8)S heterojunction photocatalysts reached to 1 190.3 μmol in 5 h,which was 25-fold and 10-fold enhanced compared with pure CdS and Mn0.8Cd0.8S.The enhanced performance of LaNiO_(3)/Mn_(0.2)Cd_(0.8)S heterojunction photocatalysts was ascribed to the formation of heterojunction between LaNiO_(3) and Mn_(0.2)Cd_(0.8)S as well as the introduced Mn2+ ion,which both can inhibit the recombination of the photoinduced electron-hole.Based on the above results,the direct Z-scheme photocatalytic reaction mechanism was proposed to elucidate the improved performance of LaNiO_(3)/Mn_(0.2)Cd_(0.8)S heterojunction photocatalysts.