HNTs@CeO_(2)-Au@Co_(3)O_(4)催化还原对硝基苯酚和染料污染物

HNTs@CeO_(2)-Au@Co_(3)O_(4)catalyst for catalytic reduction of 4-nitrophenol and dye pollutants

制备了HNTs@CeO_(2)-Au@Co_(3)O_(4)核壳中空管状复合催化剂,用于还原降解水体中对硝基苯酚(4-NP)和染料(MB,MO)污染物.采用TEM,SEM,EDS,XRD,N_(2)吸脱附,XPS等方法对催化剂微观结构和物化特征进行表征.结果表明,CeO_(2)和Co_(3)O_(4)作为内外活性层较好地分散固载Au纳米颗粒,通过界面反应构筑于埃洛石纳米管中,形成CeO_(2)/Co_(3)O_(4)叠层结构封装埃洛石载金核壳复合催化剂(HNTs@CeO_(2)-Au@Co_(3)O_(4)).该催化剂分别在3.5,8和3min内可还原去除96%以上的4-NP,MB和MO污染物,其相应的一级反应动力学速率常数(0.856,0.370,1.337min^(-1))和转换频率(10.99,1.90,2.80min^(-1))均明显优于HNTs-Au@Co_(3)O_(4),HNTs@CeO_(2)-Au和HNTs@CeO_(2)@Co_(3)O_(4)对照材料.HNTs@CeO_(2)-Au@Co_(3)O_(4)催化剂连续进行6次使用后,仍保持较高的4-NP,MB和MO污染物还原转化率(91.2%,87.3%,89.5%)和结构稳定性.独特的CeO_(2)/Co_(3)O_(4)叠层结构特征和复合组分协同增强效应有效促进了高性能催化体系的构建,极大提升了Au颗粒的催化活性和稳定性,使HNTs@CeO_(2)-Au@Co_(3)O_(4)催化剂呈现较为优异的催化效能和循环使用性能.

This paper reported the preparation of HNTs@CeO_(2)-Au@Co_(3)O_(4)core-shell hollow tubular composite catalyst for the reductive degradation of aqueous p-nitrophenol(4-NP)and dye(MB,MO)pollutants.The microstructure and physicochemical properties of the catalyst were characterized by the means of TEM,SEM,EDS,XRD,N_(2) adsorption-desorption,XPS,etc.The results showed that CeO_(2)and Co_(3)O_(4)were used as internal and external active layers to well disperse and immobilize Au nanoparticles(NPs),which were constructed upon halloysite nanotubes(HNTs)via interfacial reaction.The formed core-shell composite catalyst(HNTs@CeO_(2)-Au@Co_(3)O_(4))was based on the HNTs carrier encapsulated by the CeO_(2)/Co_(3)O_(4)laminated structure with Au NPs.The catalyst can reduce over 96%of 4-NP,MB and MO pollutants within 3.5,8 and 3min respectively,in which the corresponding first-order kinetic rate constant(0.856,0.370,1.337min-1)and turnover frequency(10.99,1.90,2.80min_(-1))were significantly superior to the control materials including HNTs-Au@Co_(3)O_(4),HNTs@CeO_(2)-Au and HNTs@CeO_(2)@Co_(3)O_(4).Besides,HNTs@CeO_(2)-Au@Co_(3)O_(4)catalyst maintained high reduction conversion of 4-NP,MB and MO pollutants and good structural integrity after 6 consecutive uses.The unique CeO_(2)/Co_(3)O_(4)laminated structural feature and synergistic enhancement effect of composite components effectively promoted the construction of the high-performance catalytic system,greatly improved the catalytic activity and stability of Au NPs,which endowed the HNTs@CeO_(2)-Au@Co_(3)O_(4)catalyst with remarkable catalytic capability and recycling performance.