原位透射电子显微镜揭示电子和光子剂量在氧化石墨烯逐步激光诱导完全脱氧中的协同作用
Synergistic Role of Electron and Photon Dose in Stepwise Laser-Induced Complete Deoxygenation of Graphene Oxide Revealed by In-situ TEM
AI总结：
研究利用原位动态透射电子显微镜监测，通过改变脉冲序列、光子和电子剂量，实现氧化石墨烯完全脱氧。明确累积电子剂量对还原机制的作用，建立多参数策略，为可控可扩展石墨烯合成提供方法。
AI中文摘要：
激光诱导还原氧化石墨烯是一种很有前景的石墨烯合成方法。本文介绍了一种采用532nm脉冲激光的逐步激光还原策略，通过原位动态透射电子显微镜实时监测。通过系统改变脉冲序列以及累积光子和电子剂量，实现了氧化石墨烯的完全脱氧并保持薄膜完整性。电子能量损失谱证实了氧官能团的完全去除和sp²石墨网络的恢复。关键的是，累积电子剂量是控制还原机制的一个有效参数，电子束曝光约占初始脱氧的5at.%，并协同降低后续激光驱动脱氧的能垒，过度电子曝光会通过裂纹形成损害薄膜完整性。最优配置在累积光子剂量为2.5 x 10³ mJ/cm²时实现完全脱氧，具有优异的面内晶体学有序性和最小的束致变薄。这项工作建立了一种通过电子束和激光辐照相结合的可控可扩展石墨烯合成的通用多参数策略。
英文摘要：
Laser-induced reduction of graphene oxide (GO) represents a highly promising route to graphene synthesis, offering spatially localized processing, elimination of hazardous chemical reagents, and compatibility with ambient conditions. Here, we introduce a stepwise laser reduction strategy employing a 532 nm pulsed laser, monitored in real-time by in situ dynamic transmission electron microscopy (DTEM). By systematically varying the pulse sequence and the cumulative photon and electron dose, complete deoxygenation of GO is achieved while preserving film integrity. Core-loss EELS confirms full removal of oxygen functional groups and restoration of the sp$^2$ graphitic network, evidenced by a $π^*-σ^*$ energy separation of 7.0 eV, in close agreement with graphite (7.1 eV). Crucially, the cumulative electron dose is identified as an active parameter governing the reduction mechanism: electron beam exposure accounts for approximately 5 at. % of the initial oxygen removal and synergistically lowers the energy barrier for subsequent laser-driven deoxygenation, while excessive electron exposure compromises film integrity through crack formation. The optimal configuration achieves complete deoxygenation at a cumulative photon dose of 2.5 x 10$^3$ mJ/cm$^2$ with superior in-plane crystallographic order and minimal beam-induced thinning. This work establishes a versatile multi-parameter strategy for controlled scalable graphene synthesis via combined electron beam and laser irradiation.
