一步低温水热合成太阳光催化性能的片花状Ag/ZnO
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摘要
采用简单原料,利用低温水热法一步合成出片花状Ag/ZnO。通过X射线衍射仪(XRD),场发射扫描电镜(FESEM),透射电镜(TEM), X射线光电子能谱仪(XPS),固体荧光光谱(PL),紫外可见漫反射光谱(UV-Vis DRS)及瞬态光电流响应等测试技术对催化剂进行了表征。探究了Ag沉积量和降解物pH值对光催化剂性能的影响。结果表明, Ag纳米颗粒沉积在片花状ZnO的表面可以有效提高其太阳光催化性能,其中Ag/ZnO-4(4%Ag,质量分数)样品光催化性能最好,其光催化降解GR黑的反应速率为纯ZnO的5.7倍。Ag/ZnO-4在pH为3～12的范围内对GR黑能保持较高的光催化降解性能,其降解前后的形貌及晶体结构没有发生明显变化,说明Ag的沉积还可以有效提高ZnO的耐酸碱能力。Ag/ZnO-4样品对其他类型的染料及抗生素甲硝唑等也具有较好的光催化降解效果。光催化循环测试结果表明Ag/ZnO-4具有良好的稳定性。自由基捕获实验结果表明·O~-_2和h~+是光催化降解过程中的主要活性物种,·OH在光催化过程中仅起辅助作用。Ag/ZnO太阳光催化性能的提高主要归因于Ag纳米颗粒的等离子体效应增加了ZnO对太阳光的吸收利用以及Ag能作为电子陷阱有效提高ZnO的光生电荷分离效率。
Nanosheets-assembled flower-like Ag/ZnO were synthesized by one pot hydrothermal method at low temperature. The samples were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscope(XPS), photoluminescence(PL), UV-Vis diffuse reflectance spectroscope(UV-Vis DRS) and transient photocurrent responses, etc. The effects of amounts of Ag deposition and pH of the degradation solution on photocatalytic performance of Ag/ZnO were also investigated. The results showed that the sunlight photocatalytic performance of ZnO could be effectively improved by the deposition of Ag nanoparticles, and Ag/ZnO-4(4% Ag, mass fraction) sample exhibited the best photocatalytic performance. The rate constant of Ag/ZnO for reactive black(GR) degradation was about 5.7 times that of pure ZnO. Furthermore, Ag/ZnO-4 could keep its excellent photocatalytic performance in pH 3～12 for GR degradation, and its morphology and crystal structure had no discernible changes after degradation. This revealed that the resistance ability of ZnO to acid and alkali was improved by the deposition of Ag. Other kinds of organic dyes as well as metronidazole were also degraded well by Ag/ZnO-4. In addition, Ag/ZnO-4 showed good stability in the process of photocatalytic cycling tests. The results of radical trapping tests indicated that both h~+ and ·O~-_2 radicals were main oxidative species, while ·OH only played assistant roles. The enhanced photocatalytic performance of Ag/ZnO was attributed to the improved sunlight absorption and the effective separation of photogenerated charge carriers, based on the surface plasmon resonance effect and serving as electron reservoirs of Ag nanoparticles, respectively.
Nanosheets-assembled flower-like Ag/ZnO were synthesized by one pot hydrothermal method at low temperature. The samples were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscope(XPS), photoluminescence(PL), UV-Vis diffuse reflectance spectroscope(UV-Vis DRS) and transient photocurrent responses, etc. The effects of amounts of Ag deposition and pH of the degradation solution on photocatalytic performance of Ag/ZnO were also investigated. The results showed that the sunlight photocatalytic performance of ZnO could be effectively improved by the deposition of Ag nanoparticles, and Ag/ZnO-4(4% Ag, mass fraction) sample exhibited the best photocatalytic performance. The rate constant of Ag/ZnO for reactive black(GR) degradation was about 5.7 times that of pure ZnO. Furthermore, Ag/ZnO-4 could keep its excellent photocatalytic performance in pH 3～12 for GR degradation, and its morphology and crystal structure had no discernible changes after degradation. This revealed that the resistance ability of ZnO to acid and alkali was improved by the deposition of Ag. Other kinds of organic dyes as well as metronidazole were also degraded well by Ag/ZnO-4. In addition, Ag/ZnO-4 showed good stability in the process of photocatalytic cycling tests. The results of radical trapping tests indicated that both h~+ and ·O~-_2 radicals were main oxidative species, while ·OH only played assistant roles. The enhanced photocatalytic performance of Ag/ZnO was attributed to the improved sunlight absorption and the effective separation of photogenerated charge carriers, based on the surface plasmon resonance effect and serving as electron reservoirs of Ag nanoparticles, respectively.
引文
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[22] Raizada P,Singh P,Kumar A,Sharma G,Pare B,Jonnalagadda S B,Thakur P.Solar photocatalytic activity of nano-ZnO supported on activated carbon or brick grain particles:role of adsorption in dye degradation [J].Applied Catalysis A:General,2014,486:159.
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[25] Muthirulan P,Meenakshisundararam M,Kannan N.Beneficial role of ZnO photocatalyst supported with porous activated carbon for the mineralization of alizarin cyanin green dye in aqueous solution [J].Journal of Advanced Research,2013,4(6):479.
[26] Xiong J,Sun Q,Chen J,Li Z,Dou S.Ambient controlled synthesis of advanced core-shell plasmonic Ag@ZnO photocatalysts [J].CrystEngComm,2016,18(10):1713.
[27] Long J,Chang H,Gu Q,Xu J,Fan L,Wang S,Zhou Y,Wei W,Huang L,Wang X,Liu P,Huang W.Gold-plasmon enhanced solar-to-hydrogen conversion on the (001) facets of anatase TiO2 nanosheets [J].Energy & Environmental Science,2014,7(3):973.
[28] Kuriakose S,Choudhary V,Satpati B,Mohapatra S.Facile synthesis of Ag-ZnO hybrid nanospindles for highly efficient photocatalytic degradation of methyl orange [J].Physical Chemistry Chemical Physics,2014,16(33):17560.
[2] Fageria P,Gangopadhyay S,Pande S.Synthesis of ZnO/Au and ZnO/Ag nanoparticles and their photocatalytic application using UV and visible light [J].RSC Advances,2014,4(48):24962.
[3] Sawant S Y,Cho M H.Facile and single-step route towards ZnO@C core-shell nanoparticles as an oxygen vacancy induced visible light active photocatalyst using the thermal decomposition of Zn(an)2(NO3)2 [J].RSC Advances,2016,6(74):70644.
[4] Feng Y,Feng N,Wei Y,Zhang G.An in situ gelatin-assisted hydrothermal synthesis of ZnO-reduced graphene oxide composites with enhanced photocatalytic performance under ultraviolet and visible light [J].RSC Advances,2014,4(16):7933.
[5] Chabri S,Dhara A,Show B,Adak D,Sinha A,Mukherjee N.Mesoporous CuO-ZnO p-n heterojunction based nanocomposites with high specific surface area for enhanced photocatalysis and electrochemical sensing [J].Catalysis Science & Technology,2016,6(9):3238.
[6] Wang H X,Wu R,Wei S H,Yu L R.Preparation of ZnTe/ZnO globular-like composites and its photocatalytic performance [J].Journal of Henan Normal University (Natural Science Edition),2016,44(3):41.(王海霞,吴荣,位顺航,余利瑞.ZnTe/ZnO类球状复合材料的制备及其光催化性能 [J].河南师范大学学报(自然科学版),2016,44(3):41.)
[7] Liu X,Iocozzia J,Wang Y,Cui X,Chen Y,Zhao S,Li Z,Lin Z.Noble metal-metal oxide nanohybrids with tailored nanostructures for efficient solar energy conversion,photocatalysis and environmental remediation [J].Energy & Environmental Science,2017,10(2):402.
[8] Andrade G R S,Nascimento C C,Lima Z M,Teixeira-Neto E,Costa L P,Gimenez I F.Star-shaped ZnO/Ag hybrid nanostructures for enhanced photocatalysis and antibacterial activity [J].Applied Surface Science,2017,399:573.
[9] Zhang X,Wang Y,Hou F,Li H,Yang Y,Zhang X,Yang Y,Wang Y.Effects of Ag loading on structural and photocatalytic properties of flower-like ZnO microspheres [J].Applied Surface Science,2017,391:476.
[10] Wang H,Liu X,Han S.The synthesis of a Ag–ZnO nanohybrid with plasmonic photocatalytic activity under visible-light irradiation:the relationship between tunable optical absorption,defect chemistry and photocatalytic activity [J].Cryst Eng Comm,2016,18(11):1933.
[11] Zhang L,Zhu D,He H,Wang Q,Xing L,Xue X.Enhanced piezo/solar-photocatalytic activity of Ag/ZnO nanotetrapods arising from the coupling of surface plasmon resonance and piezophototronic effect [J].Journal of Physics and Chemistry of Solids,2017,102:27.
[12] Jang E S,Won J H,Hwang S J,Choy J H.Fine tuning of the face orientation of ZnO crystals to optimize their photocatalytic activity [J].Advanced Materials,2006,18(24):3309.
[13] Li B,Wang Y.Facile synthesis and enhanced photocatalytic performance of flower-like ZnO hierarchical microstructures [J].The Journal of Physical Chemistry C,2010,114(2):890.
[14] Wang J,Xia Y,Dong Y,Chen R,Xiang L,Komarneni S.Defect-rich ZnO nanosheets of high surface area as an efficient visible-light photocatalyst [J].Applied Catalysis B:Environmental,2016,192:8.
[15] Zhao X H,Su S,Wu G L,Lou X D,Qin Z,Zhou J G.Preparation and sunlight photocatalytic performance of flower-like ZnO@carbon sphere core-shell structure [J].Chinese Journal of Inorganic Chemistry,2017,33(2):276.(赵晓华,苏帅,武广利,娄向东,秦喆,周建国.片花状ZnO@碳球核壳结构的制备及太阳光催化性能 [J].无机化学学报,2017,33(2):276.)
[16] Xue J,Ma S,Zhou Y,Zhang Z,Jiang P.Synthesis of Ag/ZnO/C plasmonic photocatalyst with enhanced adsorption capacity and photocatalytic activity to antibiotics [J].RSC Advances,2015,5(24):18832.
[17] Wang F,Liang L,Shi L,Liu M,Sun J.CO2-assisted synthesis of mesoporous carbon/C-doped ZnO composites for enhanced photocatalytic performance under visible light [J].Dalton Transactions,2014,43(43):16441.
[18] Wang X,Liu H,Zhang W,Cheng W,Liu X,Li X,Wu J.Synthesis and characterization of polymer-coated AgZnO nanoparticles with enhanced photocatalytic activity [J].RSC Advances,2014,4(83):44011.
[19] Ansari S A,Khan M M,Ansari M O,Lee J,Cho M H.Biogenic synthesis,photocatalytic,and photoelectrochemical performance of Ag-ZnO nanocomposite [J].The Journal of Physical Chemistry C,2013,117(51):27023.
[20] Guo Z L,Zhao H X,Zhao W.Preparation and characterization of self-cleaning and anti-reflection ZnO-SiO2 nanometric films [J].Acta Physica Sinica,2016,65(6):064206.(郭昭龙,赵海新,赵卫.纳米ZnO-SiO2自清洁增透薄膜的制备及其性能 [J].物理学报,2016,65(6):064206.)
[21] Wang J W,Wang C Y,Zhu S P,Luo X P,Li Z H,Xu L L.Benzohydroxamic acid photodegradation by prepared Ce modified TiO2 [J].Chinese Journal of Rare Metals,2018,42(4):393.(王俊蔚,王春英,祝思频,罗仙平,李智慧,徐亮亮.稀土Ce改性TiO2的制备及光催化降解苯甲羟肟酸的研究 [J].稀有金属,2018,42(4):393.)
[22] Raizada P,Singh P,Kumar A,Sharma G,Pare B,Jonnalagadda S B,Thakur P.Solar photocatalytic activity of nano-ZnO supported on activated carbon or brick grain particles:role of adsorption in dye degradation [J].Applied Catalysis A:General,2014,486:159.
[23] Wang H,Xie C,Zhang W,Cai S,Yang Z,Gui Y.Comparison of dye degradation efficiency using ZnO powders with various size scales [J].Journal of Hazardous Materials,2007,141(3):645.
[24] Muthirulan P,Devi C N,Sundaram M M.TiO2 wrapped graphene as a high performance photocatalyst for acid orange 7 dye degradation under solar/UV light irradiations [J].Ceramics International,2014,40(4):5945.
[25] Muthirulan P,Meenakshisundararam M,Kannan N.Beneficial role of ZnO photocatalyst supported with porous activated carbon for the mineralization of alizarin cyanin green dye in aqueous solution [J].Journal of Advanced Research,2013,4(6):479.
[26] Xiong J,Sun Q,Chen J,Li Z,Dou S.Ambient controlled synthesis of advanced core-shell plasmonic Ag@ZnO photocatalysts [J].CrystEngComm,2016,18(10):1713.
[27] Long J,Chang H,Gu Q,Xu J,Fan L,Wang S,Zhou Y,Wei W,Huang L,Wang X,Liu P,Huang W.Gold-plasmon enhanced solar-to-hydrogen conversion on the (001) facets of anatase TiO2 nanosheets [J].Energy & Environmental Science,2014,7(3):973.
[28] Kuriakose S,Choudhary V,Satpati B,Mohapatra S.Facile synthesis of Ag-ZnO hybrid nanospindles for highly efficient photocatalytic degradation of methyl orange [J].Physical Chemistry Chemical Physics,2014,16(33):17560.