One of the core issues in the photocatalytic oxidation of nitric oxide is the effective co nversion of NO into the final product(nitrate).More than just improving the visible light photocatalytic performance of BiOCl,...One of the core issues in the photocatalytic oxidation of nitric oxide is the effective co nversion of NO into the final product(nitrate).More than just improving the visible light photocatalytic performance of BiOCl,we aim to inhibit the generation of toxic by-product NO_(2) during this process.In this study,we demonstrate that the oxygen vacancies(OVs)modulate its surface photogene rated carrier transfer to inflect the NO conversion pathway by a facile mixed solvent method to induce OVs on the surface of BiOCl.The photocatalytic NO removal efficiency under visible light increased from 5.6%to 36.4%.In addition,the production rate of NO_(2) is effectively controlled.The effects of OVs on the generation of reactive oxygen species,electronic transfer,optical properties,and photocatalytic NO oxidation are investigated by combining density functional theory(DFT)theoretical calculations,the in situ FTIR spectra and experimental characterization.The OVs on the surface of BiOCl speed the trapping and transfer of localized electrons to activate the O_(2),producing O_(2)·,which avoid NO_(2) formation,resulting in complete oxidation of NO(NO+O_(2)·→NO_(3)).These findings can serve as the basis for controlling and blocking the generation of highly toxic intermediates through regulating the reactive species during the NO oxidation.It also can help us to understand the role of OV on the BiOCl surface and application of photocatalytic technology for safe air purification.展开更多
基金supported by the National Natural Science Foundation of China(21501016,21777011,51871037,51501024)the Innovative Research Team of Chongqing(CXTDG201602014)+1 种基金the Key Natural Science Foundation of Chongqing(cstc2017jcyjBX0052)the Plan for "National Youth Talents" of the Organization Department of the Central Committee~~
文摘窄带隙Bi OI光催化剂因电荷重组速率快而导致其可见光下的光催化效率较低.本文以NaBH4为还原剂,采用简单的常温原位组装法在Bi OI上构建氧空位、金属Bi颗粒和Bi_2O_2CO_3共作用,以克服Bi OI的缺点.在合成的三元Bi/BiOI/(BiO)_2CO_3中,氧空位、双异质结(即Bi/BiOI和Bi OI/(BiO)_2CO_3)以及Bi粒子的表面等离子体共振效应均促进了电子-空穴分离和电荷载流子浓度的增加,从而提高了可见光的整体光催化效率.将制备的催化剂用于可见光下去除连续流空气中的ppb级NO.结果表明, Bi/BiOI/(BiO)_2CO_3的NO去除率显著增强,大约为50.7%,并远高于BiOI(1.2%).密度泛函理论计算和实验结果表明, Bi/BiOI/(BiO)_2CO_3复合材料可明显促进光催化NO氧化的活性氧生成.本文可提供一个新的策略来改性窄带隙半导体和探索其他含铋异质结构的可见光驱动光催化剂.XRD结果发现, BOI-70中出现Bi和(BiO)_2CO_3的特征峰,但BOI却很微弱; XPS结果表明,高价态Bi^(3+)被NaBH4部分还原而形成低价态金属Bi颗粒,且I3d峰位结合能进一步证实了BOI-70样品中存在BiOI,由此可见,成功制备了三元Bi/BiOI/(BiO)_2CO_3异质结催化剂, EPR结果表明氧空位的产生.SEM和TEM结果表明, Bi OI和三元Bi/BiOI/(BiO)_2CO_3催化剂为纳米片组装的花状结构.HRTEM的结果进一步显示了金属铋、正方晶相Bi OI和(BiO)_2CO_3对应的晶格间距.紫外-可见光催化去除NO的测试结果表明, BOI-70(50.7%)的光催化活性明显高于BOI(1.2%)和P25(11.5%),且在循环测试实验中表现出优异的稳定性.UV-visDRS测试结果显示, BOI-70具有更强的光吸收;PL结果表明,其光生电子-空穴对的分离效率更高.ESR结果表明,参与反应的主要活性物种为·O2-和·OH自由基.DFT计算结果证实了OVs对电荷载流子的局部环境和快速传输:OV为电子捕获陷阱,使电子从OVs转移到O_2分子形成活性氧物种;O2表面的吸附能从无缺陷BiOI时的–0.29 e V降到有缺陷的–0.76 eV, O-O键长从1.30增至1.37?,说明OVs通过降低氧的吸附能可促进O2分子在光催化剂表面的吸附.综上所述,由于BiNPs的异质结效应和SPR效应以及OVs的存在, Bi/BiOI/(BiO)_2CO_3三元体系的原位组装通过增加载流子浓度和加速电子空穴分离使光催化活性显著增加.
基金the National Natural Science Foundation of China(Nos.21822601,21777011 and 21501016)the Plan for"National Youth Talents"of the Organization Department of the Central Committee。
文摘One of the core issues in the photocatalytic oxidation of nitric oxide is the effective co nversion of NO into the final product(nitrate).More than just improving the visible light photocatalytic performance of BiOCl,we aim to inhibit the generation of toxic by-product NO_(2) during this process.In this study,we demonstrate that the oxygen vacancies(OVs)modulate its surface photogene rated carrier transfer to inflect the NO conversion pathway by a facile mixed solvent method to induce OVs on the surface of BiOCl.The photocatalytic NO removal efficiency under visible light increased from 5.6%to 36.4%.In addition,the production rate of NO_(2) is effectively controlled.The effects of OVs on the generation of reactive oxygen species,electronic transfer,optical properties,and photocatalytic NO oxidation are investigated by combining density functional theory(DFT)theoretical calculations,the in situ FTIR spectra and experimental characterization.The OVs on the surface of BiOCl speed the trapping and transfer of localized electrons to activate the O_(2),producing O_(2)·,which avoid NO_(2) formation,resulting in complete oxidation of NO(NO+O_(2)·→NO_(3)).These findings can serve as the basis for controlling and blocking the generation of highly toxic intermediates through regulating the reactive species during the NO oxidation.It also can help us to understand the role of OV on the BiOCl surface and application of photocatalytic technology for safe air purification.
