$sp^{2}$/$sp^{3}$ carbon ratio in graphite oxide with different preparation times

TL;DR

This study investigates how the $sp^{2}$/$sp^{3}$ carbon ratio in graphite oxide evolves over time during preparation, revealing an exponential approach to a ratio of 0.3 over approximately 1.5 weeks, which impacts structural understanding.

Contribution

It provides new insights into the time-dependent structural evolution of graphite oxide using spectroscopic analysis, clarifying the long-term changes in carbon bonding ratios.

Findings

The $sp^{2}$/$sp^{3}$ ratio approaches 0.3 exponentially.

Characteristic time for ratio change is about 1.5 weeks.

Structural ambiguity persists due to long characteristic time.

Abstract

Graphite oxide is an amorphous insulator. Although several models have been suggested, its structure remains controversial. To elucidate this issue, 5 samples were prepared by the Brodie process and the Staudenmaier process. The electronic structure of graphite oxide was examined with x-ray absorption near edge structure and the ratio of $sp^{2}$ to $sp^{3}$ bonded carbon atoms was investigated with x-ray photoemission spectroscopy as a function of sample preparation times. It was found that this ratio approaches 0.3 exponentially with a characteristic time of 1.5 weeks. We believe this long characteristic time is the reason the structure has remained unclear.