摘要
过氧化氢是一种重要的化工原料,广泛应用于工业和生活中的多个领域.然而,目前工业上主要采用蒽醌法生产过氧化氢,该过程存在高污染和高能耗等问题.为解决上述问题,研发人员一直致力于开发新的、环保的过氧化氢生产方法.近年研究发现,压电催化生产过氧化氢是一种有前途的过氧化氢生产策略,但较低的能量转换效率阻碍了其进一步应用.Bi_(4)O_(5)Br_(2)材料因具有独特的层状晶体结构,高的化学稳定性,良好的可见光吸收及合适的能带结构被认为是具有较好应用前景的光催化材料.虽然Bi_(4)O_(5)Br_(2)的非中心对称结构赋予其独特的压电性能,但该特性往往被研究者忽视,导致其压电潜力未被充分利用.特别是,关于缺陷工程如何影响Bi_(4)O_(5)Br_(2)的压电性能仍存在许多未知之处,需要深入挖掘和探明.本文通过调节水热过程中乙二醇和水溶剂的比例构建了含有不同浓度氧空位的超薄Bi_(4)O_(5)Br_(2)(≈5 nm)纳米片,并研究其在纯水体系中的压电催化生成过氧化氢性能.X射线粉末衍射和高分辨率透射电镜结果证明Bi_(4)O_(5)Br_(2)催化剂的成功合成;X射线光电子能谱和电子顺磁共振(EPR)结果证明氧空位的成功构建.不同气氛下的催化性能实验、活性物种EPR测试和捕获实验结果均表明,过氧化氢的生成主要通过氧还原反应,同时需要水氧化反应的协同作用.此外,旋转环盘电流测试和捕获实验结果进一步表明,过氧化氢的生成主要通过两步单电子的氧还原反应.同时,压电力显微镜和多物理场仿真软件有限元模拟结果表明,超薄结构和氧空位共同增强了所制样品的压电响应和压电电势,因此促进了压电诱导的电荷分离和转移,进而产生更大的压电电流响应和更小的电化学阻抗.差分电荷和Bader电荷研究结果表明,氧空位的存在增强了催化剂与氧气之间的电荷传输和相互作用.密度泛函理论计算结果表明,氧空位增强了催化剂对氧气的吸附和活化能力,并大幅降低反应过程的吉布斯自由能.具有最优氧空位浓度的Bi_(4)O_(5)Br_(2)超薄纳米片表现出很好的催化生成过氧化氢性能,在纯水体系中过氧化氢的生成速率为620μmol g^-(1)h^(-1)(是不含氧空位Bi_(4)O_(5)Br_(2)的2.54倍),在牺牲体系中的生成速率为2700μmol g^-(1)h^(-1),催化性能优于大多数已报道的压电催化剂.综上,本文揭示了Bi_(4)O_(5)Br_(2)作为新型压电催化剂在高效合成过氧化氢中的潜力,丰富了压电催化合成过氧化氢的材料体系,同时为探索缺陷工程和纳米结构协同增强材料压电催化活性提供了参考.
The industrial anthraquinone method for H_(2)O_(2) production has the serious flaws,such as high pollution and energy consumption.Piezocatalytic H2O2 evolution has been proven as a promising strategy,but its progress is hindered by unsatisfied energy conversion efficiency.Hence,we report the efficient piezocatalytic H_(2)O_(2) generation in pure water over oxygen vacancies mediated ultrathin Bi_(4)O_(5)Br_(2)nanosheets(~5 nm).Oxygen vacancies and thin nanostructure not only enhance the piezoelectric properties of Bi_(4)O_(5)Br_(2),but also advance the separation and transfer of piezoinduced charges.Moreover,density functional theory(DFT)calculations also prove that the introduction of oxygen vacancies enhances the O_(2) adsorption and activation ability with largely decreased Gibbs free energy of the reaction pathway.Profiting from these advantages,ultrathin Bi_(4)O_(5)Br_(2)nanosheets optimized by oxygen vacancies exhibit a prominent H_(2)O_(2) evolution rate of 620μmol g^-(1)h^(-1)in pure water and 2700μmol g^-(1)h^(-1)in sacrificial system,dominated by a two-step single electron reaction,which exceeds most of reported piezocatalysts.This work demonstrates that oxygen vacancies and ultrathin structure can synergistically enhance the piezocatalytic performance,which presents perspectives into exploring the strategies of defects and nanostructure fabrication for promoting piezocatalytic activity.
作者
蔡豪
陈芳
胡程
葛伟怡
李彤
张晓磊
黄洪伟
Hao Cai;Fang Chen;Cheng Hu;Weiyi Ge;Tong Li;Xiaolei Zhang;Hongwei Huang(Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources,Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes,National Laboratory of Mineral Materials,School of Materials Science and Technology,China University of Geosciences(Beijing),Beijing 100083,China)
基金
国家自然科学基金(51972288,52272244)
中央高校基本科研业务费(2652022202).
