Structure and Property Evolution of Graphene Oxide Sheets during Low-Temperature Reduction on a Solid Substrate

Abstract

The structure and property evolution of graphene oxide (GO) during low-temperature (≤200 °C) reduction is related to the economically effective production and many behaviors of graphene-based materials, such as property tuning and long-term stability at high working temperatures. The interfacial effects on the physiochemical processes are yet to be quantified experimentally. Here, combining scanning polarization force microscopy with UV−vis absorption spectra, the formation and expansion of sp 2 domains on individual single-layered GO sheets and the opto-electronic behaviors of GO films on average at low temperatures are in situ monitored. Kinetics of the interfacial evolutions are examined. Surprisingly, unexpected faster evolution of GO sheets at interfaces than that in bulk water is observed. We find this discrepancy can be addressed if the water atmosphere is taken into account and the humidity dependence of evolution is verified. Environmental water and asymmetric moisturizing of GO are believed to play important roles in the process. Based on this, the evolution rate is modulated via adjusting the humidity. The findings shed light on the interfacial structure and property evolution processes of GO and open a new avenue to manipulate the evolution rates at low temperatures.

Effects of Graphene Redox on Its Triboelectrification at the Nanoscale

“…The increased peak absorbance after reduction is consistent with covalently bonded oxygen detaching and sp 2 -hybridized structures being repaired. The broad shoulder at ∼300 nm on the spectra of GO attributed to the n−π* transition of CO bonds disappeared after reduction (Figure e), indicating the removal of the carboxyl groups . Furthermore, all of the spectral characterizations indicate that the degree of reduction of CRGO is higher than that of TRGO.…”

“…The broad shoulder at ∼300 nm on the spectra of GO attributed to the n−π* transition of C�O bonds disappeared after reduction (Figure 1e), indicating the removal of the carboxyl groups. 46 Furthermore, all of the spectral characterizations indicate that the degree of reduction of CRGO is higher than that of TRGO.…”

Synthesis and Functionalization of Graphene Materials for Biomedical Applications: Recent Advances, Challenges, and Perspectives

“…Reproduced with permission. [ 99 ] Copyright 2020, American Chemical Society. h) High‐resolution C 1s XPS spectra of GO (left) and delphinium root extract reduced GO (right).…”

“…[ 46b ] Additionally, red shifts of the absorbance peaks appeared with an increased degree of reduction, for instance, from 226 to 258 nm after thermal treatment (reduction from GO to rGO) at 100 °C for 280 h from which different graphene materials could be identified (Figure 2g). [ 99 ]…”

“…[46b] Additionally, red shifts of the absorbance peaks appeared with an increased degree of reduction, for instance, from 226 to 258 nm after thermal treatment (reduction from GO to rGO) at 100 °C for 280 h from which different graphene materials could be identified (Figure 2g). [99] XPS radiates samples with X-rays so that the inner or valence electrons of atoms or molecules are excited and ejected. [1] Electrons excited by photons are called photoelectrons, and the intensity (or counts) or corresponding energy of these photoelectrons are needed to derive an XPS spectrum.…”