全固态Z型WO_(3)/Ag/Ag_(3)PO_(4)的制备及光降解RhB性能的研究

Preparation of all-solid Z-type WO_(3)/Ag/Ag_(3)PO_(4) and its photodegradation property of RhB

光催化剂在环境净化、太阳能转换和水分解等各个领域都具有广泛的应用。其中全固态Z型光催化剂因其结构稳定,催化性能高效等优点而备受关注。三氧化钨低毒,性质相对稳定,价带氧化能力较强,但对可见光响应能力和催化活性不强;磷酸银对可见光响应能力强,但易发生光腐蚀。Ag_(3)PO_(4)与三氧化钨带隙匹配,将二者协同复合,构建全固态Z型催化体系,可以同时提高催化剂的催化活性和稳定性。以五水合氧化钨铵盐为原料,草酸作为诱导剂,以水热法首先合成具有核壳结构的氧化钨(WO_(3)/WO_(3)-X);再通过原位沉积法,将其与Ag_(3)PO_(4)复合,构建全固态Z型催化剂WO_(3)/Ag/Ag_(3)PO_(4)(简写为AW)。通过XRD、TEM、XPS、UV-Vis等表征方法证明,原位沉积的过程中,Ag+与WO_(3)/WO_(3)-X表面的氧空位发生原位氧化还原反应,使得部分Ag^(+)被氧空位缺陷还原成Ag,并紧密附着在氧化钨表面;同时,磷酸银原位沉积在WO_(3)/Ag表面,构筑成Z型催化体系。通过AW在可见光条件下降解罗丹明B(RhB)的实验,优化其组分含量,并得到磷酸银含量为83%时催化性能最佳,在4 min时可以将RhB完全降解。最后结合光催化机理的探究,提出Z型催化机制。

Photocatalyst has a wide range of applications in environmental purification,solar energy conversion and water decomposition.Among them,all-solid Z-type photocatalytic system have attracted much attention because of their stable structure and high catalytic performance.Tungsten trioxide is a stable semiconductor with low toxicity and the hole carrier in valence band has strong oxidation capacity,but it is week in response to visible light and catalytic activity.Silver phosphate is highly responsive to visible light,but is prone to photocorrosion.Ag_(3)PO_(4) and tungsten trioxide match in band gap,so the composite catalyst catalytic can be improved in activity and stability by combining the two semiconductors to construct the all-solid Z-type catalytic system.In this study,tungsten oxide with core-shell structure(WO_(3)/WO_(3)-X)was firstly synthesized by hydrothermal method with tungsten oxide pentahydrate ammonium salt as raw material and oxalic acid as inducer.And then,the all-solid Z-type catalyst WO_(3)/Ag/Ag_(3)PO_(4)(Abbr eViated AW)was prepared by in-situ deposition method and composite with Ag_(3)PO_(4).By the characterization methods of XRD,TEM,XPS,UV-Vis and so on,it was proved that Ag^(+) and oxygen vacancy on WO_(3)/WO_(3)-X surface undergo in-situ redox reaction,so that part of Ag^(+) is reduced to Ag by oxygen vacancy defect,and closely adhered to the surface of tungsten oxide.Through the experiment of degrading rhodamine B(RhB)by AW under visible light condition,the each component content in AW is optimized.The result is that the best catalytic performance was obtained when the content of silver phosphate was 83%.And RhB could be completely degraded in 4 min.Finally,combining with the study of photocatalysis mechanism,the Z-type catalysis mechanism is proposed.