Bottom-up synthesis of multifunctional nanoporous graphene

Abstract

Nanosize pores can turn semimetallic graphene into a semiconductor and, from being impermeable, into the most efficient molecular-sieve membrane. However, scaling the pores down to the nanometer, while fulfilling the tight structural constraints imposed by applications, represents an enormous challenge for present top-down strategies. Here we report a bottom-up method to synthesize nanoporous graphene comprising an ordered array of pores separated by ribbons, which can be tuned down to the 1-nanometer range. The size, density, morphology, and chemical composition of the pores are defined with atomic precision by the design of the molecular precursors. Our electronic characterization further reveals a highly anisotropic electronic structure, where orthogonal one-dimensional electronic bands with an energy gap of ∼1 electron volt coexist with confined pore states, making the nanoporous graphene a highly versatile semiconductor for simultaneous sieving and electrical sensing of molecular species.

Bottom‐Up On‐Surface Synthesis of Two‐Dimensional Graphene Nanoribbon Networks and Their Thermoelectric Properties

“…On‐surface bottom‐up approaches using chemically designed precursors are regarded as a promising method to produce GNRs with defined edges and widths . Further, lateral fusion of parallelly aligned GNR led to generation of 2D graphene nanoribbon networks (GNNs) . However, it is difficult to efficiently create such sophisticated GNR‐linkage structures, since their formation is based on a stochastic surface reaction that requires close proximity between the precursors on the surface.…”

“…[9] However,f ully p-conjugated 2D structures attractm uch attention, since they can provide conducting carbon-based nanostructures with holey structures highly suitable for various electronic applications.U tilization of large fully p-conjugated building blocks such as GNRs, which are 1D carbon-based nanowires, is becoming ap romising approacht op roduce extended 2D pconjugated systems via surface assistedl ateral fusion of GNR chains. [10,11] On-surface bottom-up approaches using chemically designed precursors are regarded as ap romising methodt o produce GNRs with defined edges and widths. [12] Further,l ateral fusion of parallellya ligned GNR led to generation of 2D graphene nanoribbon networks (GNNs).…”

Tuning the Electronic Properties of Atomically Precise Graphene Nanoribbons by Bottom‐Up Fabrication

“…Hence, modification of the precursor molecule 1 enables tuning the electronic structure of the ribbons. For instance, molecule 10 with an added phenyl substituent in molecule 1 is designed to fabricate yield (shown in Figure a) and, experimental STS spectra has demonstrated that its band gap is 1.0 eV (Figure b), which is smaller than pristine 7‐ AGNR . 7‐ AGNRs with −CN functional groups edge modification induce a downshift on the ribbon bands of ∼0.3 eV per −CN added (Figure c and Figure d) .…”

“… Edge‐modified armchair GNRs. (a) The high‐resolution images of 7‐ phenyl‐GNRs by using a CO‐functionalized tip in constant‐height mode . (b) The corresponding dI/dV spectra of 7‐ phenyl‐GNRs .…”

“…(a) The high‐resolution images of 7‐ phenyl‐GNRs by using a CO‐functionalized tip in constant‐height mode . (b) The corresponding dI/dV spectra of 7‐ phenyl‐GNRs . (c) Constant height dI/dV image with a CO‐functionalized tip, Red arrows mark the positions of the CN groups .…”