Work Function Lowering of Graphite by Sequential Surface Modifications: Nitrogen and Hydrogen Plasma Treatment

Abstract

Graphite-related materials play an important role in various kinds of devices and catalysts. Controlling the properties of such materials is of great significance to widen the potential applications and improve the performance of such applications as field emission devices and catalyst for fuel cells. In particular, the work function strongly affects the performance, and thus development of methods to tune the work function widely is urgently required. Here, we achieved wide-range control of the work function of graphite by nitrogen and hydrogen plasma treatments. The time of hydrogen plasma treatment and the amount of nitrogen atoms doped beforehand could control the work function of graphite from 2.9 to 5.0 eV. The formation of a surface dipole layer and the nitrogen-derived electron donation contributed to such lowering of the work function, which is advantageous for applications in various fields.

Compacted Self‐Assembly Graphene with Hydrogen Plasma Surface Modification for Robust Artificial Electronic Synapses of Gadolinium Oxide Memristors

“…[ 55–57 ] It is worth noting that with the increase in H 2 plasma modification time, the CPD increases gradually, i.e., the decrease in work function of CSA graphene films, owing to the removal of functional groups and the introduction of hydrogen bonds by H 2 plasma. [ 58,59 ] Figure 3f shows the Hall mobility and resistivity of CSA graphene films with H 2 plasma surface modification. The resistivity of CSA graphene films first decreases gradually and then increases dramatically with the increase in H 2 plasma modification time.…”

Photocathode Investigation for Ultrafast Electron Microscopy

“…We hypothesize that the emission from the graphite region has to do with surface contamination, specifically surface modification decreasing the work function after cooling from thermionic emission [6]. These findings demonstrate the importance of understanding the photoemission process for UEM photocathodes.…”

Pyridinic-Type N-Doped Graphene on Cobalt Substrate as Efficient Electrocatalyst for Oxygen Reduction Reaction in Acidic Solution in Fuel Cell

“…The correlation between the work function of graphene and the ORR activity has been reported for many graphene-based catalysts. − The work function of freestanding 3NG py is 5.10 eV, which is higher than that of Co-supported 3NG py with a work function of 4.54 eV. This implies that the Co substrate reduced the work function of pyridinic N-doped graphene.…”