Controlled Growth Of Mesoporous Barium Titanate And Its Photocatalytic Properties

In this work,strontium titanate(SrTiO3,STO)is synthesized by hydrothermal method.Sodium carboxymethylcellulose(CMC)and hexadecyl trimethyl ammonium bromide(CTAB)are utilized to control growth of morphology and pore size.Consequently,mesoporous and microporous STO have been obtained using these two additives successfully.Average pore size of mesoporous STO is around 10 nm,average pore size decreases 37.45%.Average pore size distribution is around 1.89 nm of microporous STO,average pore size decreases 88.45%.Then,the degradation performances are tested,pore size and dye molecules effect is analyzed.Interestingly,cross-linked STO is controlled by CMC and its size decreases with increase of CMC amount.On the other hand,cube,porous sphere and polyhedron microporous STO are obtained with increasing of CTAB amount.Photocatalytic degradation performance,kinetics and mechanism to unitary and binary dye solutions are explored.Subsequently,Fe and Ag doping and Pd-Ni-P amorphous alloy modification are successfully complished on STO.Degradation ratio to methyl orange(MO)increases 30%,50%and 40%respectively.Lastly,different initial concentration of dye solutions and reaction pH to degradation kinetics and surface C potential are studied.Increasing kinetic constant is explained.Meanwhile,degradation model of binary dye solution is obtained.(1)Photodegradation performance of rhodamine B(RhB)and methyl orange(MO)is compared:mesoporous>microporous STO(for both RhB and MO).Degradation order is as following:RhB>MO.(2)CMC controlled mesoporous STO shows preferential photodegradation performance to MB in binary dye solution(RhB+MB),which is better than CTAB controlled microporous STO.Kinetic ratio of methylene blue(MB)to RhB is 3.50 that means degradation rate of MB(from 10 nm mesoporous STO)is 3.50 faster than RhB.Pore size with 10 nm shows preferential and selective degradation performance to MB.Degradation order is as following:MB>RhB.(3)In order to get enhanced photodegradation performance,Fe and Ag are selected to dope and Pd-Ni-P amorphous alloy is modified on STO.Fe and Ag formed oxide decreases 0.1 eV of STO Eg.After 30 min of illuminance,degradation ratio of MO increases by 30%,50%and 40%.Oxide and surface alloy promote degradation of MO.(4)Effect of pH and species of binary dye solutions are mainly explored for STO.According to ? potential and molecular orbitals(the lowest unoccupied molecular orbital(LUMO)and highest occupied molecular orbital(HOMO)),degradation models of binary dye solutions are obtained.RhB sensitizing STO and sensitized MB promote separation of carriers.Cyclic voltammetry is used to illustrate pH-induced kinetics change.Degradation order is as following:MB>RhB>MO.H+ concentration change has affected competitive adsorption and led to redox potential change molecules.