Spectroscopic investigation of nitrogen- functionalized carbon materials Kevin N. Wood, a,e Steven T. Christensen, b Dennis Nordlund, c Arrelaine A. Dameron, b Chilan Ngo, d Huyen Dinh, b Thomas Gennett, b Ryan O’Hayre a and Svitlana Pylypenko d * Carbon materials are used in a diverse set of applications ranging from pharmaceuticals to catalysis. Nitrogen modification of car- bon powders has shown to be an effective method for enhancing both surface and bulk properties of as-received material for a number of applications. Unfortunately, control of the nitrogen modification process is challenging and can limit the effectiveness and reproducibility of N-doped materials. Additionally, the assignment of functional groups to specific moieties on the surface of nitrogen-modified carbon materials is not straightforward. Herein, we complete an in-depth analysis of functional groups present at the surface of ion-implanted Vulcan and Graphitic Vulcan through the use of X-ray photoelectron spectroscopy (XPS) and near edge X-ray adsorption fine structure spectroscopy (NEXAFS). Our results show that regardless of the initial starting materials used, nitrogen ion implantation conditions can be tuned to increase the amount of nitrogen incorporation and to obtain both similar and reproducible final distributions of nitrogen functional groups. The development of a well-controlled/reproducible nitrogen implantation pathway opens the door for carbon supported catalyst architectures to have improved numbers of nucleation sites, decreased particle size, and enhanced catalyst-support interactions. Copyright © 2016 John Wiley & Sons, Ltd. Additional supporting information may be found in the online version of the publisher’s web-site. Keywords: Nitrogen; Carbon Support; Spectroscopy; catalysis; XPS; NEXAFS Introduction Carbon-based materials are among the most studied systems in the scientific community because of their versatility, low cost, availabil- ity, and a wide range of properties. [1–5] The physical, chemical, opti- cal, and electronic properties of carbon materials vary among their allotropic forms and greatly depend on the structure, morphology, and surface composition of the carbon. High surface area carbon materials have been extensively used for sorption, sensing, catalysis, and storage applications. In many energy generation and storage applications, carbon materials are used as supports to facilitate dis- persion of noble and non-noble catalysts. Among commercially available carbon supports, carbon blacks and activated carbons are the most commonly used, with various nanostructured carbons such as graphene, fibers, nanotubes, and mesoporous morphol- ogies emerging in recent decades. Functionalization of these carbon-based materials allows researchers to tune carbons surface properties, increasing its utility across a wide range of applications. In the case of carbon supports employed in catalytic processes, the most important characteristics are surface area, structural orga- nization, porosity, and surface composition. [1] Synthesis and/or manufacturing routes often greatly influence the surface composi- tion, leading to a range of concentrations for graphitic and oxide components. [2,5–7] Many different oxygen functional groups have been detected on carbon support materials including carboxyl, car- bonyl, quinone, ether, hydroxyl, phenol, and lactone groups. These groups influence the acid/base nature of the support surface and act as nucleation centers during the deposition of metal catalysts. [2,8–10] In addition, the properties of carbon supports can be altered by the introduction of other heteroatoms, such as sulfur, phosphorous, boron, fluorine, iodine, and nitrogen. [3,11–14] Replace- ment of the carbon atoms with other heteroatoms changes local chemical reactivity, improving nucleation and enhancing binding energy between the support and metal nanoparticles. [15] Because of its size and the presence of a lone pair of electrons, nitrogen in- troduces defects into the carbon structure of graphitic carbon matrices. [2,4,5] As a convincing body of recent work has shown, func- tionalization of the carbon support with heteroatoms is now widely regarded as one of the promising routes for improving the interac- tions between the support and noble-metal electrocatalysts for both reducing and oxidizing catalytic reactions in polymer electro- lyte membrane fuel cell (PEMFC) applications. [2,3,16–19] Nitrogen * Correspondence to: Svitlana Pylypenko, Department of Chemistry and Geochemistry, Colorado School of Mines, 1012 14th Street, Golden, CO 80401, USA. E-mail: spylypen@mines.edu a Department of Metallurgical and Materials Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, CO, 80401, USA b National Renewable Energy Laboratory, 15013 Denver West Pkwy, Golden, CO, 80401, USA c Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, CA, 94023, USA d Department of Chemistry and Geochemistry, Colorado School of Mines, 1012 14th Street, Golden, CO, 80401, USA e Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA Surf. Interface Anal. 2016, 48, 283–292 Copyright © 2016 John Wiley & Sons, Ltd. Special issue article Received: 2 October 2015 Revised: 27 January 2016 Accepted: 3 March 2016 Published online in Wiley Online Library (wileyonlinelibrary.com) DOI 10.1002/sia.6017 283