通过氟掺杂调控TiO_(2)的d带中心以增强光催化产H_(2)O_(2)活性  

Regulation of d‐band center of TiO_(2) through fluoride doping for enhancing photocatalytic H_(2)O_(2) production activity

作　　者：赵艳艳 张淑敏 吴珍 朱必成 孙国太 张建军 Yanyan Zhao;Shumin Zhang;Zhen Wu;Bicheng Zhu;Guotai Sun;Jianjun Zhang(College of Biology Pharmacy and Food Engineering,Shangluo University,Shangluo 726000,Shaanxi,China;Hunan Key Laboratory of Applied Environmental Photocatalysis,Changsha University,Changsha 410022,Hunan,China;Department of Chemical Engineering,OrdosInstitute of Technology,Ordos 017000,Inner Mongolia,China;Laboratory of Solar Fuel,Faculty of Materials Science and Chemistry,China University of Geosciences,Wuhan 430074,Hubei,China)

机构地区：[1]商洛学院生物医药与食品工程学院,陕西商洛726000 [2]长沙学院应用环境光催化湖南省重点实验室,湖南长沙410022 [3]鄂尔多斯应用技术学院化学工程学院,内蒙古鄂尔多斯017000 [4]中国地质大学(武汉)材料与化学学院,太阳燃料实验室,湖北武汉430074

出　　处：《Chinese Journal of Catalysis》2024年第5期219-230,共12页催化学报（英文）

基　　金：国家自然科学基金(52202375,52372294,22302183,22362004);陕西省教育厅协同创新项目(22JY015).

摘　　要：光催化产双氧水(H_(2)O_(2))以太阳光、水和空气中的氧气作为原料,将光能转变为化学能,是一种绿色高效节能环保的新技术,具有较好的应用前景.光催化产H_(2)O_(2)主要包括三个关键步骤:(1)催化剂在高能入射光激发下产生光生电子和空穴;(2)光生电子-空穴对分离并迁移到催化剂表面;(3)光生电子与催化剂表面吸附的氧气发生反应生成超氧自由基,其继续与水和光生电子反应,产生H_(2)O_(2).因此,氧气在催化剂表面吸附性能的强弱对光催化产H_(2)O_(2)的性能有着重要影响.d带中心理论表明,金属的d带能级高低决定了催化剂表面活性位点对小分子物质的吸附强度,能级越高,催化剂对小分子物质的吸附能力越强.TiO_(2)具有制备简单、无毒、理化性质稳定、导价带位置跨越多个氧化还原电位等诸多优势,在光催化生产H_(2)O_(2)领域具有较好的应用前景.提升TiO_(2)的d带中心可以提高其对小分子物质如O_(2)的吸附性能,有效提升其光催化产H_(2)O_(2)的活性.本文从氟离子掺杂提升TiO_(2)的d带中心增强对O_(2)的吸附性能入手,通过第一性理论计算、电子顺磁共振实验、飞秒瞬态吸收光谱等方法研究光生载流子的传输机理,阐明F/TiO_(2)光催化产H_(2)O_(2)活性增强机制,并对TiO_(2)光催化产H_(2)O_(2)的前景提出了展望.首先,分别以钛酸四异丙酯和氟化铵作为钛源和氟源,通过溶胶-凝胶法结合高温煅烧制得了F/TiO_(2)光催化剂.第一性理论计算结果表明,F-体相掺杂导致TiO_(2)的电荷分布不均匀,使得d带中心上移,从而增强TiO_(2)与表面吸附O_(2)的相互作用,降低表面氧的吸附能,最终提高光催化生成H_(2)O_(2)的效率.电子顺磁共振实验结果表明,晶格中F-离子的存在诱导了还原性Ti^(3+)中心的形成,这些还原性Ti^(3+)中心可以提供电荷补偿所需的额外电子.O_(2)温度程序解吸实验结果表明,F/TiO_(2)对O_(2)的化Titanium dioxide(TiO_(2))has received extensive attention for photocatalytic hydrogen peroxide(H_(2)O_(2))production,with the d-band center related to the adsorption performance,which affects the photocatalytic reaction process.Herein,an ingenious strategy to lower the antibonding-orbital occupancy in the Ti 3d orbital by fluoride ion(F-)doping is proposed,with density functional theory calculations predicting that F-doping into TiO_(2) induces a non-uniform charge distribution and enables an upshift of the d-band center in F/TiO_(2).This manipulation provides accessible active centers with favorable d-band energy levels,which can improve the charge-transfer behavior,strengthen the interaction between the adsorbed oxygen and the photocatalyst,and reduce the adsorption energy of oxygen,eventually promoting the photocatalytic H_(2)O_(2) production rate.The experimental results further confirm that a lower antibonding-orbital occupancy can intensify the adsorption of atomic oxygen at the Ti sites.Electron paramagnetic resonance experiment reveals that the presence of F-ions in the lattice induces the formation of Ti^(3+)centers that localize the extra electron needed for charge compensation.Femtosecond transient absorption(fs-TA)spectroscopy suggests that photogenerated electrons are transferred from the conduction band of F/TiO_(2) to the Ti^(3+)surface states and surface F-ions,expediting the separation of electrons and holes.Consequently,with F-doping in TiO_(2),the photocatalytic H_(2)O_(2) production yields improved from 277 to 467μmol·g-1·h^(-1),with ethanol as a sacrificial reagent.This study provides a new strategy for regulating the d-band center to optimize the adsorption strength between the photocatalyst and oxygen atoms and achieve enhanced photocatalytic H_(2)O_(2) production performance.

关 键 词：反键轨道 d带中心 氧吸附 电荷转移 双氧水生成 

分 类 号：O643.36[理学—物理化学] O644.1[理学—化学] TQ116.2[化学工程—无机化工]