Tuning the Doping Types in Graphene Sheets by N Monoelement

Abstract

The doping types of graphene sheets are generally tuned by different dopants with either three or five valence electrons. As a five-valence-electrons element, however, nitrogen dopants in graphene sheets have several substitutional geometries. So far, their distinct effects on electronic properties predicted by theoretical calculations have not been well identified. Here, we demonstrate that the doping types of graphene can be tuned by N monoelement under proper growth conditions using chemical vapor deposition (CVD), characterized by combining scanning tunneling microscopy/spectroscopy, X-ray/ultraviolet photoelectron spectroscopy, Hall effect measurement, Raman spectroscopy, and density functional theory calculations. We find that a relatively low partial pressure of CH (mixing with NH) can lead to the growth of dominant pyridinic N substitutions in graphene, in contrast with the growth of dominant graphitic N substitutions under a higher partial pressure of CH. Our results unambiguously confirm that the pyridinic N leads to the p-type doping, and the graphitic N leads to the n-type doping. Interestingly, we also find that the pyridinic N and the graphitic N are preferentially separated in different domains. Our findings shed light on continuously tuning the doping level of graphene monolayers by using N monoelement, which can be very convenient for growth of functional structures in graphene sheets.

Seed‐Initiated Synthesis and Tunable Doping Graphene for High‐Performance Photodetectors

“…Moreover, because different STS spectra are attained from films of doped graphene, we can infer that protrusions observed above are produced by dopants, rather than defects. As electronic coupling effects are similar, we can also found a circuitous shift of location of Dirac point as the STM tip crosses the region doped with N . These data have similarity with features of doped graphene reported previously …”

Reactive Plasma N-Doping of Amorphous Carbon Electrodes: Decoupling Disorder and Chemical Effects on Capacitive and Electrocatalytic Performance

“…Functional N-sites such as pyridinic-N (N Py ), pyrrolic-N (N Pr ), graphitic-N (N G ), and N-oxides (N Ox ) can be incorporated into the carbon structure (Serp and Figueiredo, 2009 ) resulting in reactive centers that can significantly affect interfacial interactions with redox species and intermediates (Choi et al, 2014 ; Guo et al, 2016 ; Wu et al, 2017 ; Behan et al, 2018 , 2019b ) and, consequently, electrocatalytic activity. Nitrogen sites can also affect the electronic properties of carbon electrodes, as they might serve as both n-type or p-type dopants (Zhao et al, 2011 ; Ma et al, 2018 ), and can increase carbon conductivity and metallic character (Robertson, 2002 ; Choi et al, 2014 ; Behan et al, 2017 ; Hoque et al, 2019 ). Furthermore, the role of nitrogen atoms as impurities and the experimental methods used for its incorporation can affect the organization of the carbon scaffold, introducing voids, vacancies, defects and non-graphitizable regions that have dramatic effects on both capacitive and faradaic responses (Zhou et al, 2010 ; Legrain et al, 2015 ; Salanne et al, 2016 ; Stamatin et al, 2016 ; Zhang et al, 2016 ; Behan et al, 2017 , 2019a ; Ng et al, 2018 ; Dou et al, 2019 ; Hoque et al, 2019 ; Jia et al, 2019 ; Saurel et al, 2019 ).…”

Supercritical Fluid‐Facilitated Exfoliation and Processing of 2D Materials

“…[172] SCFs can promote the doping of many other materials such as TiO 2 . [172] SCFs can promote the doping of many other materials such as TiO 2 .…”

“…When using GO instead of graphite in scNH 3 , the doping level was improved to 10.8 at%, comparable to the value obtained by annealing (220 °C) with ammonia gas. Graphene doping types can be changed by adjusting scNH 3 pressure and by introducing a second phase like CH 4 …”