羧酸类前驱体对铁酸铋物相及性质的影响

Influence of Carboxylic Acid Precursors on Phase and Properties of Bismuth Ferrate

利用羧基的桥联以及螯合作用形成5种含Bi^(3+)和Fe^(3+)双金属的异核配位前驱体,然后通过热分解前驱体法制备铁酸铋纳米颗粒。采用TG,XRD,FT-IR,SEM,FL和电化学等手段研究配体对前驱体热稳定性、灼烧产物组成、表面形貌、电化学性能、光催化性能以及磁性强弱的影响。结果显示:前驱体的热稳定性随配体所含羧基数目以及与金属形成螯合环数目的增加而增强;由甘氨酸所得灼烧产物为单相铁酸铋,由氨三乙酸所得灼烧产物为铁酸铋与氧化铋的复合物;而其他配体所得灼烧产物为铁酸铋和软铁矿构成的复合物;所有灼烧产物对MO的光降解均具有催化性,其中由氨三乙酸所得灼烧产物的催化效果最好,由甘氨酸所得灼烧产物的催化效果最差,光照4 h MO仅降解40%,从灼烧产物组成、两相比例及粒径等方面分析了引起催化性差异的原因;电化学测试结果显示由甘氨酸所得灼烧产物电子传递阻力大,而由氨三乙酸所得灼烧产物电子传递快,寿命较长;磁铁对由甘氨酸所得灼烧产物不能吸引,而对其他配体所得灼烧产物均可较强吸引。

Five kinds of heteronuclear coordination precursors containing Bi^(3+)and Fe^(3+)bimetals were formed by bridging and chelating actions of carboxyl groups,and then bismuth ferrate nanoparticles were prepared by thermal decomposition of the precursors.TG,XRD,FT-IR,SEM,FL and electrochemical tests were used to study the effects of ligands on the thermal stability of precursors,the composition,surface morphology,electrochemical and photocatalytic properties,and magnetic strength of the calcined products.The results show that the thermal stability of the precursor increases with the increase of the number of carboxyl groups contained in the ligand and the number of chelated rings formed with the metal.The calcination products obtained from glycine(Gly)and aminotriacetic acid(NTA)coordination precursors are single-phase bismuth ferrate and a complex of bismuth ferrate and bismuth oxide,respectively,while the products obtained from other precursors are complexes of bismuth ferrate and soft iron ore.All the calcination products are catalytic for the photodegradation of MO,among which the calcined products obtained from NTA coordination precursor exhibit the best catalytic activity,while the calcined products obtained from Gly coordination precursor show the worst catalytic activity(only 40%of MO is degraded after 4 h light irradiation).The reasons for the difference in catalytic activity were analyzed from the aspects of the composition,the ratio of the two phases,and the particle size of the calcined products.Electrochemical test results show that the calcined products obtained from Gly coordination precursor have high electric transfer resistance,while the calcined products obtained from NTA coordination precursor have fast electric transfer and longer electronic lifetime.Finally,the magnet cannot attract the calcined products obtained from Gly coordination precursor,but it can strongly attract the calcined products obtained from other precursors.