Rondiya Sachin R, Karbhal Indrapal, Jadhav Chandradip D, Nasane Mamta P, Davies Thomas E, Shelke Manjusha V, Jadkar Sandesh R, Chavan Padmakar G, Dzade Nelson Y
School of Chemistry, Cardiff University Main Building, Park Place Cardiff CF10 3AT Wales UK
Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory Pune 411008 MH India.
RSC Adv. 2020 Jul 10;10(43):25988-25998. doi: 10.1039/d0ra03360j. eCollection 2020 Jul 3.
The unique structural merits of heterostructured nanomaterials including the electronic interaction, interfacial bonding and synergistic effects make them attractive for fabricating highly efficient optoelectronic devices. Herein, we report the synthesis of MnO nanorods and a rGO/MnO nano-heterostructure using low-cost hydrothermal and modified Hummers' methods, respectively. Detailed characterization and confirmation of the structural and morphological properties are done X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Compared to the isolated MnO nanorods, the rGO/MnO nano-heterostructure exhibits impressive field emission (FE) performance in terms of the low turn-on field of 1.4 V μm for an emission current density of 10 μA cm and a high current density of 600 μA cm at a relatively very low applied electric field of 3.1 V μm. The isolated MnO nanorods display a high turn-on field of 7.1 for an emission current density of 10 μA cm and a low current density of 221 μA cm at an applied field of 8.1 V μm. Besides the superior FE characteristics of the rGO/MnO nano-heterostructure, the emission current remains quite stable over the continuous 2 h period of measurement. The improvement of the FE characteristics of the rGO/MnO nano-heterostructure can be ascribed to the nanometric features and the lower work function (6.01 and 6.12 eV for the rGO with 8% and 16% oxygen content) compared to the isolated α-MnO(100) surface ( = 7.22 eV) as predicted from complementary first-principles electronic structure calculations based on density functional theory (DFT) methods. These results suggest that an appropriate coupling of rGO with MnO nanorods would have a synergistic effect of lowering the electronic work function, resulting in a beneficial tuning of the FE characteristics.
异质结构纳米材料独特的结构优点，包括电子相互作用、界面键合和协同效应，使其在制造高效光电器件方面具有吸引力。在此，我们分别报告了使用低成本水热法和改进的Hummers法合成MnO纳米棒和rGO/MnO纳米异质结构。通过X射线衍射（XRD）、场发射扫描电子显微镜（FESEM）和透射电子显微镜（TEM）对结构和形态特性进行了详细表征和确认。与孤立的MnO纳米棒相比，rGO/MnO纳米异质结构在发射电流密度为10 μA/cm²时的低开启场为1.4 V/μm，在相对非常低的3.1 V/μm外加电场下具有600 μA/cm²的高电流密度，表现出令人印象深刻的场发射（FE）性能。孤立的MnO纳米棒在发射电流密度为10 μA/cm²时的开启场为7.1 V，在8.1 V/μm的外加电场下电流密度为221 μA/cm²。除了rGO/MnO纳米异质结构具有优异的场发射特性外，在连续2小时的测量期间发射电流保持相当稳定。rGO/MnO纳米异质结构场发射特性的改善可归因于纳米尺寸特征以及与基于密度泛函理论（DFT）方法的互补第一性原理电子结构计算预测的孤立α-MnO(100)表面（功函数 = 7.22 eV）相比更低的功函数（含8%和16%氧含量的rGO分别为6.01和6.12 eV）。这些结果表明，rGO与MnO纳米棒的适当耦合将产生降低电子功函数的协同效应，从而对场发射特性进行有益的调节。
