氧掺杂对VN-g-C3N4催化剂光催化固氮性能的影响

Effect of Oxygen on Photocatalytic Nitrogen Fixation Performance of N Vacancy-embedded Graphitic Carbon Nitride

采用介质阻挡放电等离子体法合成了氧原子掺杂的具有氮空穴的石墨相氮化碳催化剂(g⁃C3N4),并对催化剂的结构和形貌进行了表征分析.结果表明,等离子体处理没有改变催化剂的形貌,并同时将氮空穴和氧原子引入了g⁃C3N4的晶格.在可见光条件下,制备的共掺杂g⁃C3N4催化剂的铵离子产率高达5.9 mg·L^-1·h^-1·g^-1 cat,分别是具有氮空穴的g⁃C3N4和纯g⁃C3N4的2.2倍和20倍,同时还表现出优异的催化稳定性.密度泛函理论计算结果显示,与具有氮空穴的g⁃C3N4相比,氧原子的引入能提高氮空穴对反应物氮气分子的活化能力,提高光催化固氮性能.

N vacancy and oxygen co-doped g-C3N4 with outstanding N2 photofixation ability was synthesized by dielectric barrier discharge plasma treatment.XRD,UV-Vis,N2 adsorption,SEM,XPS,PL and TPD were used to characterize the as-prepared catalysts.The result shows that plasma treatment does not change the morphology of as-prepared catalyst but introduce nitrogen vacancies and oxygen into g-C3N4 lattice simultaneously.The as-prepared co-doped g-C3N4 displays the ammonium ion production rate as high as 5.9 mg·L^-1·h^-1·g^-1 cat,which is 2.2 and 20 times that of individual N vacancy-doped g-C3N4 and neat g-C3N4,as well as good catalytic stability.Experimental and density functional theory(DFT)calculation results indicate that,compared with individual N vacancies doping,the introduction of oxygen can promote the activation ability of N vacancies to N2 molecule,leading to the promoted N2 photofixation performance.