Bottom-up Assembly of Nanoporous Graphene with Emergent Electronic States
Bottom-up Assembly of Nanoporous Graphene with Emergent Electronic States
复制标题
DOI：
10.1021/jacs.0c05235
复制
发表时间：
2020-08-05
影响因子：
15
通讯作者：
Crommie, Michael F.
中科院分区：
文献类型：
--
作者：
Jacobse, Peter H.;McCurdy, Ryan D.;Crommie, Michael F.
将纳米级孔结合到石墨烯片中，使其能够从不可渗透的半金属转变为半导体纳米筛。纳米多孔石墨烯对于从高性能半导体器件通道到原子级薄分子筛膜的应用是理想的，并且它们的性能高度依赖于原子水平上的孔的周期性和再现性。使用自上而下的光刻方法在石墨烯中实现精确的纳米孔拓扑结构已被证明是具有挑战性的，这是由于在原子水平上的差的结构控制。或者，可以通过自下而上合成的石墨烯纳米带的横向融合来制造原子级精确的纳米尺寸的孔。然而，这种技术通常需要在纳米取向形成之后的附加高温交叉耦合步骤，其固有地产生差的横向共轭，从而导致机械和电子两者弱连接的2D材料。在这里，我们展示了一种新的自下而上的方法，通过一个单一的，温和的退火步骤后，初始聚合物的形成，形成完全共轭的纳米多孔石墨烯。我们发现出现的界面局域化的电子状态内的大量的带隙的石墨烯纳米杂化产生一个分散的二维低能带的状态。我们表明，这个低能带可以根据组成单链纳米带的边缘状态来合理化。这些2D状态在孔周围的局部化使得这种材料对于需要电子敏感分子筛的应用特别有吸引力。
The incorporation of nanoscale pores into a sheet of graphene allows it to switch from an impermeable semimetal to a semiconducting nanosieve. Nanoporous graphenes are desirable for applications ranging from high-performance semiconductor device channels to atomically thin molecular sieve membranes, and their performance is highly dependent on the periodicity and reproducibility of pores at the atomic level. Achieving precise nanopore topologies in graphene using top-down lithographic approaches has proven to be challenging due to poor structural control at the atomic level. Alternatively, atomically precise nanometer-sized pores can be fabricated via lateral fusion of bottom-up synthesized graphene nanoribbons. This technique, however, typically requires an additional high temperature cross-coupling step following the nanoribbon formation that inherently yields poor lateral conjugation, resulting in 2D materials that are weakly connected both mechanically and electronically. Here, we demonstrate a novel bottom-up approach for forming fully conjugated nanoporous graphene through a single, mild annealing step following the initial polymer formation. We find emergent interface-localized electronic states within the bulk band gap of the graphene nanoribbon that hybridize to yield a dispersive two-dimensional low-energy band of states. We show that this low-energy band can be rationalized in terms of edge states of the constituent single-strand nanoribbons. The localization of these 2D states around pores makes this material particularly attractive for applications requiring electronically sensitive molecular sieves.