“We Are Here!” Oxygen Functional Groups in Carbons for Electrochemical Applications

Abstract

Heteroatom doping of carbon networks may introduce active functional groups on the surface of the material, induce electron density changes that alter the polarity of the carbon surface, promote the formation of binding sites for molecules or ions, or make the surface catalytically active for different reactions, among many other alterations. Thus, it is no surprise that heteroatom doping has become a well-established strategy to enhance the performance of carbon-based materials for applications ranging from water remediation and gas sorption to energy storage and conversion. Although oxygen functionalization is sometimes inevitable (i.e., many carbon precursors contain oxygen functionalities), its participation in carbon materials performance is often overlooked on behalf of other heteroatoms (mainly nitrogen). In this Mini-review, we summarize recent and relevant publications on the effect that oxygen functionalization has on carbonaceous materials performance in different electrochemical applications and some strategies to introduce such functionalization purposely. Our aim is to revert the current tendency to overlook it and raise the attention of the materials science community on the benefits of using oxygen functionalization in many state-of-the-art applications.

Advances in Micro-/Mesopore Regulation Methods for Plant-Derived Carbon Materials

“…In other words, besides C, there are many other elements, such as O, N, S, P and Si, which can boost the development of more advanced materials and functional materials. The existing forms of O in plant-derived carbon materials are mainly -OH, -COOH, C=O and C-O-C, and these functional groups can be retained in the carbon network even at high temperatures, which can enhance the wettability of the surface of carbon material and provide the pseudocapacitance for supercapacitors and lithium batteries to improve the electric capacity [ 31 ]. N atoms exist in carbon materials mainly in the form of pyridine nitrogen, pyrrole nitrogen and graphite nitrogen.…”

Probing elemental speciation in hydrochar produced from hydrothermal liquefaction of anaerobic digestates using quantitative X-ray diffraction

“…In contrast, having the organic carbon in the form of O-heterocyclics and Nheterocyclics in the hydrochar is required for manufacturing hydrochar-based carbon nanotubes with high-performance supercapacitance. 37,38 For process optimization, understanding the elemental speciation in hydrochar aids in selecting operating conditions to obtain hydrochar with properties suitable for more sustainable application. However, previous studies of the chemistry of elemental speciation in hydrochar is limited to HTL systems processing only cellulose or lignin as the feedstock at a narrow range of operating conditions.…”

“…In contrast, having the organic carbon in the form of O -heterocyclics and N -heterocyclics in the hydrochar is required for manufacturing hydrochar-based carbon nanotubes with high-performance supercapacitance. 37,38…”

Bottom-Up Synthesis Strategies Enabling the Investigation of Metal Catalyst-Carbon Support Interactions

“…Specifically, the carbon's structure and surface chemistry strongly influence its proton-, electron-, and oxygen-transfer characteristics [1,2]. Oxygen-containing groups play a substantial role as they are ubiquitous on carbon surfaces [1,8] and control the hydrophilichydrophobic, acid-base, and local electronic structure of the surface through distortion of carbon's sp 2 network [9]. Hence, they may influence the adsorption and chemical events involved in the catalytic transformations, for example, through proton shuttling, as well as the electronic structure of the metal active phase itself.…”

“…A recent study disclosed an interfacial charge transfer for Pd/C that scaled with the amount of surface oxygen moieties and that altered the selectivity of the Pd/C catalyst for the liquid-phase hydrogenation of cinnamaldehyde [10]. Nevertheless, the exact role of oxygen-containing groups on the properties of the carbon support and the decorating metal nanoparticles remains poorly understood [9]. The intertwined confinement, chemical, and electronic effects were proven to be difficult to decouple in many previous studies causing ambiguity in the literature and hampering the rational design of these catalysts [2].…”