Boehm Titration Revisited (Part II): A Comparison of Boehm Titration with Other Analytical Techniques on the Quantification of Oxygen-Containing Surface Groups for a Variety of Carbon Materials

Jan Schönherr,Johannes R Buchheim,Philipp Adelhelm,Peter Scholz

doi:10.3390/c4020022

Jan Schönherr, Johannes R Buchheim + Show 2 more

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https://doi.org/10.3390/c4020022

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Abstract

The use of the Boehm titration (BT) method as an analytical tool for the quantification of oxygen-containing surface groups is systematically investigated for oxidized carbon black, carbon nanotubes and two active carbons with specific surface areas between 60 and 1750 m2 g−1. The accuracy of the BT method is quantitatively compared with results from elemental analysis (EA), temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). Overall, the results from TPD are in line with the values obtained by BT. Both show the equal ratio of the oxygen groups to each other. Within the series of carbon samples, all methods provide similar trends for the total oxygen content yet the absolute numbers are deviating significantly. Reasons for these discrepancies are discussed and linked to the specific characteristics of the different methods. As the BT method is a solution based method, it only probes the surface fraction of the carbon that is accessible to the base solution. That means, it probes the relevant fraction for applications where carbon is in contact to aqueous solutions. Overall, the BT method can be conveniently applied to a broad range of carbon materials as long as the samples are sufficiently hydrophilic and of the enough sample amount is provided.

Highlights

The Boehm titration (BT) is one of few methods that enables a quantification of specific oxygen-containing surface groups on carbon materials [1,2,3]
Before applying the BT method, all carbon materials were characterized by N2 physisorption and scanning electron microscope (SEM)
Four structurally very different carbon materials with varying morphology and specific surface were analyzed by the BT method and results were compared with other analytical methods (TPD-mass spectrometry (MS), X-ray photoelectron spectroscopy (XPS), and elemental analysis (EA))

Summary

Introduction

The Boehm titration (BT) is one of few methods that enables a quantification of specific oxygen-containing surface groups on carbon materials [1,2,3] It provides absolute values based on a chemical reaction. The method is in principle simple and cost-effective, other methods such as temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) or elemental analysis (EA) are more popular nowadays. This is mainly because a full analysis by BT can be time-consuming and because variations in the measurement protocol can strongly influence the outcome of the analysis (low robustness). Once a standard protocol is followed, the BT method can be considered as quite attractive

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