Peng Yi, Lu Bingzhang, Wu Feng, Zhang Fengqi, Lu Jia En, Kang Xiongwu, Ping Yuan, Chen Shaowei
Department of Chemistry and Biochemistry , University of California , 1156 High Street , Santa Cruz , California 95060 , United States.
New Energy Research Institute, School of Environment and Energy , South China University of Technology, Guangzhou Higher Education Mega Center , Guangzhou , Guangdong 510006 , China.
J Am Chem Soc. 2018 Nov 14;140(45):15290-15299. doi: 10.1021/jacs.8b08035. Epub 2018 Oct 31.
Photoinduced charge transfer across the metal oxide-organic ligand interface plays a key role in the diverse applications of metal oxide nanomaterials/nanostructures, such as photovoltaics, photocatalysis, and optoelectronics. Thus far, most studies are focused on molecular engineering of the organic chromophores, where the charge-transfer properties have been found to dictate the photo absorption efficiency and eventual device performance. Yet, as the chromophores are mostly bound onto the metal oxide surfaces by hydroxyl or carboxyl anchors, the impacts of the bonding interactions at the metal oxide-ligand interface on interfacial charge transfer have remained largely unexplored. Herein, acetylene derivatives are demonstrated as effective surface capping ligands for metal oxide nanoparticles, as exemplified with TiO, RuO, and ZnO. Experimental studies and first-principles calculations suggest the formation of M-O-C≡C- core-ligand linkages that lead to effective interfacial charge delocalization, in contrast to hopping/tunneling by the conventional M-O-CO- interfacial bonds in the carboxyl-capped counterparts. This leads to the generation of an interfacial state within the oxide bandgap and much enhanced sensitization of the nanoparticle photoluminescence emissions as well as photocatalytic activity, as manifested in the comparative studies with TiO nanoparticles functionalized with ethynylpyrene and pyrenecarboxylic acid. These results highlight the significance of the unique interfacial bonding chemistry by acetylene anchoring group in facilitating efficient charge transfer through the oxide-ligand interfacial linkage and hence the fundamental implication in their practical applications.
光诱导电荷在金属氧化物 - 有机配体界面间的转移，在金属氧化物纳米材料/纳米结构的多种应用中起着关键作用，如光伏、光催化和光电子学领域。到目前为止，大多数研究都集中在有机发色团的分子工程上，已发现电荷转移特性决定了光吸收效率和最终的器件性能。然而，由于发色团大多通过羟基或羧基锚定在金属氧化物表面，金属氧化物 - 配体界面处的键合相互作用对界面电荷转移的影响在很大程度上仍未得到探索充分探索。在此，乙炔衍生物被证明是金属氧化物纳米颗粒有效的表面封端配体，以TiO、RuO和ZnO为例。实验研究和第一性原理计算表明，与羧基封端对应物中传统的M - O - CO - 界面键的跳跃/隧穿不同，形成了M - O - C≡C - 核心 - 配体键，导致有效的界面电荷离域。这导致在氧化物带隙内产生一个界面态，并大大增强了纳米颗粒光致发光发射的敏化以及光催化活性，这在与乙炔基芘和芘羧酸功能化的TiO纳米颗粒的对比研究中得到了体现。这些结果突出了乙炔锚定基团独特的界面键合化学在促进通过氧化物 - 配体界面连接进行有效电荷转移方面的重要性，因此对其实际应用具有重要的基础意义。
