Tim-Patrick Fellinger

Efficient Metal-Free Oxygen Reduction in Alkaline Medium on High-Surface-Area Mesoporous Nitrogen-Doped Carbons Made from Ionic Liquids and Nucleobases

Mesoporous nitrogen-doped carbon materials with high surface areas up to 1500 m(2) g(-1) were conveniently made by the carbonization of nucleobases dissolved in an all-organic ionic liquid (1-ethyl-3-methylimidazolium dicyanamide). Using hard templating with silica nanoparticles, this process yields high-surface-area nitrogen-doped carbon materials with nitrogen contents as high as 12 wt %, narrow mesopore size distribution of ca. 12 nm diameter, and local graphitic carbon structure. It is demonstrated that the resulting nitrogen-doped carbons show very high catalytic activity, even in the metal-free case in the oxygen reduction reaction (ORR) for fuel cells. Specifically, the as-prepared materials exhibit a low onset voltage for ORR in alkaline medium and a high methanol tolerance, compared with those of commercial 20 wt % Pt/C catalyst. We regard this as a first step toward an all-sustainable fuel cell, avoiding noble metals.

Mesoporous Nitrogen-Doped Carbon for the Electrocatalytic Synthesis of Hydrogen Peroxide

Mesoporous nitrogen-doped carbon derived from the ionic liquid N-butyl-3-methylpyridinium dicyanamide is a highly active, cheap, and selective metal-free catalyst for the electrochemical synthesis of hydrogen peroxide that has the potential for use in a safe, sustainable, and cheap flow-reactor-based method for H(2)O(2) production.

A general salt-templating method to fabricate vertically aligned graphitic carbon nanosheets and their metal carbide hybrids for superior lithium ion batteries and water splitting

The synthesis of vertically aligned functional graphitic carbon nanosheets (CNS) is challenging. Herein, we demonstrate a general approach for the fabrication of vertically aligned CNS and metal carbide@CNS composites via a facile salt templating induced self-assembly. The resulting vertically aligned CNS and metal carbide@CNS structures possess ultrathin walls, good electrical conductivity, strong adhesion, excellent structural robustness, and small particle size. In electrochemical energy conversion and storage such unique features are favorable for providing efficient mass transport as well as a large and accessible electroactive surface. The materials were tested as electrodes in a lithium ion battery and in electrochemical water splitting. The vertically aligned nanosheets exhibit remarkable lithium ion storage properties and, concurrently, excellent properties as electrocatalysts for hydrogen evolution.

25th Anniversary Article: “Cooking Carbon with Salt”: Carbon Materials and Carbonaceous Frameworks from Ionic Liquids and Poly(ionic liquid)s

This review surveys recent work on the use of ionic liquids (ILs) and polymerized ionic liquids (PILs) as precursors to synthesize functional carbon materials. As solvents or educts with negligible vapour pressure, these systems enable simple processing, composition, and structural control of the resulting carbons under rather simple and green synthesis conditions. Recent applications of the resulting nanocarbons across a multitude of fields, such as fuel cells, energy storage in batteries and supercapacitors, catalysis, separation, and sorption materials are highlighted.

Improving Hydrothermal Carbonization by Using Poly(ionic liquid)s

Pores for thought: Porous nitrogen-doped carbon materials (HTC Carbon with PILs) composed of spherical nanoparticles, and also those with Au-Pd core-shell nanoparticles embedded (Au-Pd@N-Carbon) were synthesized. These materials can be prepared from sugars by hydrothermal carbonization (160-200 °C) in the presence of poly(ionic liquid)s (PILs), which act as a stabilizer, pore-generating agent, and nitrogen source.

Capacitive Deionization using Biomass-based Microporous Salt-Templated Heteroatom-Doped Carbons

Microporous carbons are an interesting material for electrochemical applications. In this study, we evaluate several such carbons without/with N or S doping with regard to capacitive deionization. For this purpose, we extent the salt-templating synthesis towards biomass precursors and S-doped microporous carbons. The sample with the largest specific surface area (2830 m(2)  g(-1) ) showed 1.0 wt % N and exhibited a high salt-sorption capacity of 15.0 mg g(-1) at 1.2 V in 5 mM aqueous NaCl. While being a promising material from an equilibrium performance point of view, our study also gives first insights to practical limitations of heteroatom-doped carbon materials. We show that high heteroatom content may be associated with a low charge efficiency. The latter is a key parameter for capacitive deionization and is defined as the ratio between the amounts of removed salt molecules and electrical charge.

Merging Single-Atom-Dispersed Silver and Carbon Nitride to a Joint Electronic System via Copolymerization with Silver Tricyanomethanide

Herein, we present an approach to create a hybrid between single-atom-dispersed silver and a carbon nitride polymer. Silver tricyanomethanide (AgTCM) is used as a reactive comonomer during templated carbon nitride synthesis to introduce both negative charges and silver atoms/ions to the system. The successful introduction of the extra electron density under the formation of a delocalized joint electronic system is proven by photoluminescence measurements, X-ray photoelectron spectroscopy investigations, and measurements of surface ζ-potential. At the same time, the principal structure of the carbon nitride network is not disturbed, as shown by solid-state nuclear magnetic resonance spectroscopy and electrochemical impedance spectroscopy analysis. The synthesis also results in an improvement of the visible light absorption and the development of higher surface area in the final products. The atom-dispersed AgTCM-doped carbon nitride shows an enhanced performance in the selective hydrogenation of alkynes in comparison with the performance of other conventional Ag-based materials prepared by spray deposition and impregnation-reduction methods, here exemplified with 1-hexyne.

Bifunctional Metal‐Free Catalysis of Mesoporous Noble Carbons for Oxygen Reduction and Evolution Reactions

Electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key reactions in lithium-oxygen batteries (LOBs) being a promising candidate to store renewable energies due to their high specific energy. However current development on LOBs is suffering from unsuitable catalysts. In particular, carbon-based catalysts were found to perform poorly in this system. Here, we show that metal-free mesoporous nitrogen-doped carbons (meso-NdCs) offer highly promising performances in both ORR and OER; they act as bifunctional catalysts, and can be synthesized by a very simple method. The efficient electrocatalytic activity of ORR and OER was used in a LOB cell during discharge and charge, respectively, and the present system showed a lower overpotential comparable to metal-based catalysts in LOB system. Thus, we demonstrate that meso-NdCs act as a new and affordable candidate for the efficient bifunctional oxygen catalysis, therefore can be applied to many energy-related applications.

Mesoporous Nitrogen Doped Carbon Supported Platinum PEM Fuel Cell Electrocatalyst Made From Ionic Liquids

A multitude of new and improved catalyst materials and concepts for membrane fuel cells were developed over the last decade. The requirements of these catalysts are low cost, high activity and durability. For example, platinum based catalyst concepts such as Pt monolayer catalysts, 2] Pt skin catalysts, Pt multimetallic catalysts, and dealloyed bimetallic Pt core-shell nanoparticle catalysts show promising activities based on Pt mass and Pt surface area for the oxygen reduction reaction (ORR). Furthermore, non-noble metal catalyst concepts could reduce the costs, but they currently still do not meet the activity targets for commercial fuel cell electrocatalysts. To improve the durability of fuel cell catalysts, also the support material is becoming more important. Oxidation resistance of the support material is one point of concern. Alternatives to pure carbon blacks (e.g. Vulcan XC 72R) were evaluated for the oxygen reduction, such as carbon nanotubes, 24] silicon carbide derived carbons, hollow spherical carbons, nitrogen modified carbons, or titanium-based materials. Especially nitrogen doped carbons show interesting properties like high conductivity, mesoporosity and the opportunity to adjust the nitrogen content in the support material. In this communication, we report the synthesis of a mesoporous nitrogen doped carbon supported platinum catalyst (Pt/ meso-BMP) based on an ionic liquid as nitrogen/carbon precursor and the evaluation of the catalytic system for ORR. Further, we analyzed the long-term behavior of this new catalyst and compared it with commercial high surface area carbon (HSAC) supported platinum catalyst. The mesoporous nitrogen doped carbon supported platinum nanoparticle fuel cell electrocatalyst (Pt/meso-BMP) was prepared by a two-step synthesis, as shown in Figure 1. In the first step, the mesoporous nitrogen doped carbon material (meso-BMP) was synthesized corresponding to the reference 35] by using N-butyl-3-methylpyridinedicyanamide (BMPdca) as ionic liquid compound. As evaluated by X-ray photoelectron spectroscopy (XPS) and elemental analysis (EA) the nitrogen content of 14.2 wt. % (XPS)/17.2 wt. % (EA) is very high. The variation of the values can be explained by the surface specificity of XPS measurements. In the second step, platinum nanoparticles were deposited on the meso-BMP substrate. The deposition of Pt occurred by a wet impregnation–freeze-drying method and followed by thermal annealing in a reductive atmosphere. Shown in Figure 2 are the XRD profiles for meso-BMP and Pt/meso-BMP. The as synthesized meso-BMP support material exhibits broad XRD reflections at 2 q= 26.1 and 42.98 corresponding to the inter (002) and intra (101) lattice planes of graphitized carbon. The reference powder diffraction patterns of (111), (200), and (220) lattice planes for pure face centered Figure 1. Synthesis route for mesoporous nitrogen doped carbon supported platinum nanoparticle catalyst.

Nitro Lignin-Derived Nitrogen-Doped Carbon as an Efficient and Sustainable Electrocatalyst for Oxygen Reduction

The use of lignin as a precursor for the synthesis of materials is nowadays considered very interesting from a sustainability standpoint. Here we illustrate the synthesis of a micro-, meso-, and macroporous nitrogen-doped carbon (NDC) using lignin extracted from beech wood via alkaline hydrothermal treatment and successively functionalized via aromatic nitration. The so obtained material is thus carbonized in the eutectic salt melt KCl/ZnCl2. The final NDC shows an excellent activity as electrocatalyst for the oxygen reduction reaction.