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Inorganic clathrates have been extensively investigated owing to their unique and intriguing atomic structure as well as their potential as thermoelectric materials. The connection between the chemical ordering and the physical properties has, however, remained elusive. Here, this relation is uncovered through a combination of first-principles calculations, atomistic simulations, and experimental measurements of thermodynamic as well as electrical transport properties. This approach is, specifically, used to reveal the existence of an order-disorder transition in the quaternary clathrate series Ba8AlxGa16-xGe30. The results, furthermore, demonstrate that this phenomenon is responsible for the discontinuity in the heat capacity that has been observed previously. Moreover, the unusual temperature dependence of both Seebeck coefficient and electrical conductivity can be fully explained by the alterations of the band structure brought about by the phase transformation. It is finally argued that the phenomenology described here is not limited to this particular material but should be present in a wide range of inorganic clathrates and could even be observed in other materials that exhibit chemical ordering on at least one sublattice.

A novel template-free colloidal assembly method that combines colloidal zeolite (silicalite-1) suspensions in a water-in-oil emulsion with an evaporation-induced assembly process has been developed for preparing hierarchical micro-/mesoporous zeolite microspheres (MZMs). Such particles have an interconnected mesoporosity and large mesopore diameters (25-40 nm) combined with 5.5 Å diameter micropores of the zeolite nanoparticles. The method developed has the advantages of employing mild synthesis conditions, a short preparation time, and not requiring the use of a mesoporogen template or post-treatment methods. The method provides a new range of micro-/mesoporous zeolites with tunable mesoporosity dictated by the size of the zeolite nanoparticles. It also offers the possibility of combining several zeolite particle sizes or optionally adding amorphous silica nanoparticles to tune the mesopore size distribution further. It should be generally applicable to other types of colloidal zeolite suspensions (e.g. ZSM-5, zeolite A, beta) and represents a new route amenable for cost-effective scale-up.

In the synthesis of iron-chelating ordered mesoporous nitrogen-functionalized carbon (Fe–OMC) catalysts, the removal of the silica template is a crucial and critical step. The silica removal method used today for the Fe–OMCs is based on the very toxic hydrofluoric acid (HF), which usage should be limited where possible. Therefore, the aim of this study is to establish a mild (user-friendly), yet efficient, etch method based on dilute sodium hydroxide (NaOH), which does not impair the catalytic performance of the catalyst, to replace the currently used HF method. A comparison between catalysts etched with HF versus NaOH was performed in order to gain understanding how the two etch methods influence the final catalysts in terms of electrochemical, structural and catalytic properties. The NaOH etch was found to successfully remove the silica template, and interestingly, also improve the catalytic performance. The improved activity is explained by a carbon activation process occurring in the catalyst treated with the NaOH etch. With these findings, we show that it is possible to remove the silica in a more user-friendly way and simultaneously increase the catalysts’ performance by activation of the carbon.

A two-step procedure for the surface functionalization of carbon materials has been developed. In the first step, mesoporous carbon (CMK3), carbon black (XC-72R Vulcan), and activated carbon (AC) are bromomethylated efficiently under mild conditions using commercially available reagents, resulting in reproducible surface bromine loadings, the concentrations of which correlate to the carbon's surface area. The resulting bromomethylated materials display excellent stability over the course of months when stored under ambient conditions. In the second step, substitution reactions with a variety of nucleophiles proceed efficiently. Example nucleophiles include azide, amines, ammonia and iodide, and exhibit high conversion yields. To demonstrate the application of this two-step functionalization method, bromomethylated CMK3, Br-CMK3, was reacted with ethylenediamine (EN) to form EN-CMK3, which was used as the conductive host for the sulfur cathode in lithium–sulfur (Li–S) batteries. Impregnation of EN-CMK3 with a lithium polysulfide-containing electrolyte with either lithium nitrate (LiNO3) or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the supporting electrolyte increases the battery performance relative to pristine CMK3. With LiNO3, the surface-bonded EN allows for increased sulfur use and results in higher capacities of ca. 300 mA h g−1; with LiTFSI, the EN groups attenuate the polysulfide shuttle (LiPS shuttle) and the initial charging efficiency (ICE) is increased substantially from 3% to 73%. These results provide a proof-of-principle of the versatility of bromomethylated carbons as a useful starting material for a variety of functional materials.

Ordered mesoporous titania, prepared via low-temperature spray deposition, was examined as an anode material for lithium ion batteries. The material exhibits an exceptionally high electrochemical capacity of 680 mA h g−1 during the first discharge, which rapidly decreases over the following cycles. The capacity stabilizes at around 170 mA h g−1 after 50 cycles and the material delivers 83 mA h g−1 at high charge/discharge rates (10C). A combination of electrochemical and structural characterization techniques were used to study the charge/discharge behavior of the material and the origin of the irreversible capacity. To determine the effect of cycling on the structure of the material, X-ray absorption spectroscopy (XAS) and energy filtered TEM were carried out on pristine and cycled samples in intercalated and deintercalated states. Titanium K-edge XAS measurements showed that intercalated lithium affects the NEXAFS region. By comparing peak intensity ratios, we propose a method to quantify the amount of lithium inserted into the titania structure and to differentiate between lithium bound in close proximity to titanium, and lithium bound further away from titanium. Additionally, we suggest that the irreversible loss in capacity is due to the formation of phases that are stable, and thereby electrochemically inactive, over the electrochemical cycling conditions applied.

By combining two enzymes, formate dehydrogenase (FateDH) and formaldehyde dehydrogenase (FaldDH), it is possible to drive the thermodynamically unfavorable conversion of CO2 to formaldehyde. For this purpose, the enzymes were coimmobilized in siliceous mesostructured cellular foams (MCFs). A high degree of adsorption of both enzymes was achieved by coimmobilizing the enzymes sequentially, i.e., first FateDH and then FaldDH. The highest conversion rate was obtained with an enzyme mass ratio of 1:15 (FateDH/FaldDH). Using MCF functionalized with mercaptopropyl groups (MCF-MP), the activity increased ∼4 times compared to the enzymes free in solution. To probe the distance between the two enzymes, they were separately labeled with either Cy3 or Cy5 dyes and studied with Forster resonance energy transfer (FRET). An increased energy transfer was observed when the enzymes were coimmobilized in MCF-MP, suggesting that the two enzymes are in close proximity, resulting in higher conversion of CO2 to formaldehyde.

Iron ion-chelating ordered mesoporous carbon (Fe-OMC) catalysts are a class of non-precious metal catalysts for the oxygen reduction reaction in fuel cells. Here, the performance of Fe-OMC catalysts is studied in relation to variations in conditions employed during their synthesis. Specifically, we studied the effects of (i) the hydration state of the iron salt precursor, (ii) the aging time after mixing of the precursor solution and (iii) the relative amount of iron to N/C-precursor used during synthesis. The formation of complexes between the iron ion and the N/C-precursor was investigated by NMR spectroscopy and it was shown that a complex is formed with the amine group of the N/C-precursor being closest to the iron ion. All three parameters studied (i, ii, and iii) were found to have a significant impact on the complex formation between the iron ion and the N/C-precursor as well as on the performance of the resulting catalyst materials.

Mg2Si1-xSnx alloys with nominal values of x [0.03:0.18] were synthesized at 780 °C by solid-state reaction from Mg2Si and Mg2Sn and subsequently annealed at either 680 or 580 °C. Their microstructure was investigated by X-ray diffraction using the Rietveld method. Depending on the treatment temperature and the nominal composition, the solid solutions split into different Si- and/or Sn-rich Mg2Si1-xSnx phases. Traces of spinodal decomposition were observed for the samples with a low Sn content independent of treatment temperature due to the limited diffusion kinetics when entering the miscibility gap. A similar effect was observed when applying a higher cooling rate to the samples with higher Sn concentration. In this case, the samples experience thermodynamic spinodal decomposition being located in the spinodal region sufficiently long time at higher temperatures. Samples treated in the miscibility gap showed an agreement of the Si-rich binodal line with calculated phase diagrams. However, the Sn-rich binodal line stays undefined, perhaps due to grain boundary pinning of diffusing atoms. The study elucidates the possibility of tailoring the microstructure of magnesium silicide-stannide alloys utilizing merely judiciously designed heat treatment protocols. A particular attention is brought to spinodal decomposition, which has the potential to reduce the lattice thermal conductivity.

Temperature-dependent phase-separation, clouding, has been observed in suspensions of silica nanoparticles surface-functionalized with methyl-poly(ethylene glycol) silane. Interparticle interactions and conformational changes of the grafted poly(ethylene glycol) chains influence the observed cloud points, and can be controlled by electrolyte concentration and pH. These findings open new routes to tailoring properties of Pickering emulsions.

Evolution of the polymorph selectivity of titanium dioxide was studied under acidic and low-temperature synthesis conditions. Short synthesis times resulted in high relative amounts of the rutile phase, and long synthesis times resulted in high relative amounts of the brookite and anatase phases. The effect of titania precursor concentration was investigated and found to have a large impact on the polymorph selectivity. As the reaction proceeds with time, changes in the chemical environment, caused in particular by the gradually decreasing titania precursor concentration, are therefore likely the cause of the change in polymorph selectivity observed.

A facile low-temperature synthesis method of crystalline titanium dioxide nanoparticles has been developed, and the effect of temperature and acidity on polymorph selectivity has been systematically investigated. The crystal polymorph of titanium dioxide could be tuned by carefully controlling the condensation rate of titania. Conditions providing high condensation rate favoured the formation of the anatase and brookite phases, while lowering the condensation rate yielded higher rutile content. The reaction was found to proceed either in liquid state for reactions performed at low temperatures and high acidity or in a sol–gel manner for higher temperatures and lower acidity. The aggregation behaviour was found to be strongly affected by the employed synthesis conditions and by the crystal polymorph formed. The design of a facile low-temperature synthesis system with predictive control of polymorph selectivity is important for further development of titania-based materials for applications where type of polymorph is vital, such as photocatalytic and photonic.

A new concept for noble metal-free polymer electrolyte membrane fuel cell catalysts has been developed. The catalysts consist of chelated transition metal ions incorporated in a nitrogen-functionalized ordered mesoporous carbon matrix, which is evidenced by a combination of X-ray absorption fine structure analysis and high-resolution transmission electron microscopy. The ordered mesoporous carbon matrix of the catalyst offers an exceptionally high specific surface area and allows conceptually for a high degree of tuning, enabling controlled variability of, e.g., pore size and curvature and thickness of the pore walls of the catalysts. Single cell fuel cell tests of membrane electrode assemblies prepared with a cathode made of iron- or cobalt-based versions of the catalyst show high power densities, reaching up to one-third of a commercial Pt/C catalyst at 0.6 V.

The highly oxygenated hydrocarbon triethylene glycol dimethyl ether or triglyme (CH3O-(C2H4O-)(3)CH3) was found to efficiently reduce NOx under lean conditions over Ag/Al2O3, but gave a low NOx conversion over Cu-ZSM-5. Furthermore, triglyme showed an extraordinary promoting effect when added together with propene as reducing agent for NOx over Ag/Al2O3 at low temperature. This is most likely due to that triglyme promotes the activation of propene.

Commercial Cu-ZSM-5- and Ag/Al2O3-based lean NOx catalysts were evaluated in a synthetic exhaust gas bench with the fuels RME, B30, B15, Agrodiesel 15, GTL, NExBTL, and MK1 as reducing agents. The influence of reductant was larger for Ag/Al2O3, albeit moderate, whereas the Cu-zeolite showed the highest NOx conversion at lower temperature for all alternative fuels tested.

A new direct synthesis methodology for the preparation of mesoporous titania with hexagonal mesostructure and with walls of tunable crystallinity and crystallite size has been developed. As the crystallites grow they eventually reach a point where they are too big to fit within the pore walls, the mesoorder becomes distorted and is finally lost. It is run at an unprecedented low temperature of 40 °C without the need for an autoclave or high-temperature post-treatment procedures and is thus compatible with low temperature stable substrates. High-resolution transmission electron microscopy and electron diffraction reveal that the pore walls of the mesoordered material consists of anatase TiO2 nanoparticles. The method allows for a wide choice of synthesis time during which the anatase crystallites grow slowly within the range of 2−5 nm in size but needs to be kept such that the crystallites have not yet grown too large for them to be coassembled into an ordered mesostructure.

Above 300 °C, gas phase reactions occur between dimethyl ether (DME), NO and O2 generating NO2. The influence of these reactions on DME-SCR was studied in a setup that decoupled the occurrence of gas phase reactions from catalyst temperature. NOx conversion decreased at 350 °C and increased at 250 °C due to less DME available and higher NCO conversion with NO2, respectively.

Microporous semiconducting crystal structures are exceedingly rare and their usefulness for applications typical for microporous semiconductors is largely related to their sorption properties and to their semiconductor response to sorption. The sorption properties of the unique crystalline microporous semiconducting antimony(III) oxide telluride K-SBC-1 were evaluated by means of temperature-resolved diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, thermogravimetric analysis (TGA/DSC), and X-ray powder diffraction. K-SBC-1 was found to demonstrate heat-induced reversible sorption and desorption-induced rearrangements of guest water molecules. Upon heating to 300 degrees C 66% of the water content of K-SBC-1 desorbed. Desorption of water could be made more facile through activation of K-SBC-1 by heat treatment and then occurred at room temperature in a flow of nitrogen. These are unique properties compared to the few known related structures and thus represent a significant advancement in the field of microporous semiconductors. (C) 2010 Elsevier Inc. All rights reserved.

Lean reduction of NOx with DME occurs with high selectivity to N-2 over Al2O3 between 300 degrees C and 550 degrees C with a maximum of 47% at 380 degrees C, and with lower selectivity over Ag/Al2O3 between 250 degrees C and 400 degrees C due to the catalysts' sensitivity to gas phase radical reactions and activity for NOx reduction with methanol.

The influence of syntheses parameters of zeolite ZSM-5 on the lean NOx reduction activity and hydrothermal stability of Cu-ZSM-5 has been investigated. The hydrothermal stability of Cu-ZSM-5 was found to depend on the aluminium source used and on the presence of Ca(OH)2 in the synthesis mixture for ZSM-5.

Micrometre-sized aluminium particles are used as pigments in silver inks and for environmental reasons it is desirable to develop water-based formulations of such pigments. In waterborne coatings, however, aluminium is prone to react with water, with subsequent hydrogen gas evolution and loss of the silvery lustre. The protection against water of aluminium pigments by adsorption of either a nonionic or an anionic surfactant has been evaluated. Phosphate esters with different lengths of the hydrocarbon tail have been synthesised and tested, and were found to provide very effective protection of the pigments. Sodium dodecyl sulphate (SDS), on the other hand, was completely ineffective as inhibitor, even though the adsorption isotherm was about the same as for the structurally similar sodium dodecyl phosphate (SDP). This difference may be explained by formation of different types of complexes with the aluminium oxide surface. Outer-sphere complexes are suggested for SDS, whilst SDP can form more stable inner-sphere complexes. Tests with the non-surface active methyl phosphate as inhibiting agent gave insufficient protection, indicating that surface activity is crucial for the inhibition, and that the use of the phosphates as such is not enough to give proper protection. The work shows that amphiphilic compounds having phosphate as anchoring group are efficient in providing water resistance to aluminium pigments.

Dimethyl ether (DME) is an interesting alternative fuel to diesel, but is not an efficient reductant in lean NO x conversion over typical diesel HC-SCR catalysts. Comparatively high deNO x activity was found over H-ZSM-5 in the presence of water, giving reduction of 28% NO and 37% NO2 respectively with a DME/NO x -ratio of 4.

A series of ZSM-5 samples with similar SiO2/Al2O3 ratio was synthesised using different aluminum sources and by including varying amounts of calcium hydroxide during the synthesis. The samples were subsequently ion-exchanged with Cu-ions, and evaluated with respect to deNOx activity in the absence and presence of water. The choice of aluminum source and the presence of calcium hydroxide during the zeolite synthesis affected the lean deNOx activity of Cu-ZSM-5.

Commercially available lean NOx catalyst and lean NOx adsorber samples were tested in a synthetic exhaust gas bench with DME as reducing agent. The LNA catalyst gave a very high NOx conversion (> 80 %) over a wide temperature range (275–450°C), and with low concentration of by-products such as NH3, N2O and methanol. The Cu-zeolite based LNC catalyst, however, showed practically no NOx conversion.

Ag/Al2O3 catalysts (2 wt% Ag) have been prepared and calcined at different temperatures to render catalysts with different silver particle size or silver configuration. The differences in activity and selectivity of these catalysts are related to the activity for oxidation of NO and hydrocarbons, the NOx storage properties, and to the oxidation state of silver.

Nanosized, crystalline rutile TiO2 was synthesized at room temperature using a microemulsion-mediated system followed by hydrothermal treatment. The formed rutile had a specific surface area of about 40 m2 g-1 and the rutile crystals had dimensions of about 10 nm × 150 nm, which aggregated into 200-1000 nm sized bundles. The adsorption and photocatalytic degradation of diisopropyl fluorophosphate (DFP) and dimethyl methylphosphonate (DMMP) over these rutile TiO2 nanoparticles in dry and wet synthetic air was investigated by in situ diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy during simulated solar light illumination. The methyl and isopropyl groups do not dissociate upon adsorption on either dry or humidified rutile nanoparticles. The F atom in DFP is, however, easily hydrolyzed and is readily dissociated upon interaction with hydroxyls on the TiO2 surfaces and leads to a destabilization of the DFP molecule. The initial solar light induced photodegradation rate for DFP and DMMP is 5.9 × 10-4 and 1.0 × 10-4 s-1 in dry conditions and 8.1 × 10-4 and 0.7 × 10-4 s-1 in wet conditions (corresponding to 2-3 monolayers (ML) water coverage), respectively. The main intermediate partial oxidation surface products are found to be surface bound formate-carboxylate-carbonate (R-COO-) and phosphate (R-POO-) species. Among them η1-coordinated acetone and μ-formate, bicarbonate, and bidentate R-POO- moieties are detected. These surface species accumulate on the surface during the entire illumination period (60 min), and lead to a decreased total oxidation rate. Controlled humidification of the rutile surface leads to a reduction of the concentration of R-COO- intermediates, while at the same time maintaining approximately the same rate of DFP and DMMP photooxidation. The latter is due to blocking of Ti surface cation sites, which prevents the formation of strongly bonded surface compounds, in particular μ-coordinated R-COO- and R-POO- species. The findings show that, it is possible to optimize the sustained photocatalytic degradation of organic phosphorous compounds by controlled humidification of the reaction gas.

Thin films of ordered mesoporous anatase have been prepared using a dip-coating procedure. Silver nanoparticles were introduced into the mesopores using wet impregnation followed by heat treatment....

The selective catalytic reduction (SCR) of NO x over zeolite H-ZSM-5 with ammonia was investigated using in situ FTIR spectroscopy and flow reactor measurements. The adsorption of ammonia and the reaction between NO x , O2 and either preadsorbed ammonia or transiently supplied ammonia were investigated for either NO or equimolar amounts of NO and NO2. With transient ammonia supply the total NO reduction increased and the selectivity to N2O formation decreased compared to continuous supply. The FTIR experiments revealed that NO x reacts with ammonia adsorbed on Bronsted acid sites as $${\rm NH}_{4}^{+}$$ ions. These experiments further indicated that adsorbed - $${\rm NO}_{2}^{-}$$ is formed during the SCR reaction over H-ZSM-5.

A flexible method of preparing and macroscopically aligning nanoparticles of crystalline silver into millimeter long fibers is presented. The approach utilizes the dual functionality of a reverse hexagonal liquid crystalline template containing a built-in reducing agent facing the aqueous domain. The method is advantageous in that its slow kinetics allows for a thorough introduction of a silver salt into the liquid crystal before the reduction takes place, allowing for an efficient loading of he template and a retained mesoscopic ordering as evidenced by SAXS. It was confirmed by H-1 NMR that the oxyethylene groups of the amphiphilic polymer reduce the silver ions while being oxidized to aldehydes. The silver nanoparticles are uniform in size and in the same size range as the diameter of the aqueous domain of the liquid crystal (3 nm), further supporting that the silver particles form inside the liquid crystal. TEM images confirm the macroscopic alignment of silver nanoparticles into fibrils and the packing of fibrils into millimeter long fibers. The diameter of the fibrils and fibers ranges from 30 nm to several hundreds of micrometers. Electron diffraction analysis of a collection of silver nanoparticles confirms their crystallinity as three diffraction rings could be indexed to the face centered cubic structure of silver. A key to the successful macroscopic alignment of the nanoparticles is that the particles are formed inside the liquid crystal, thus minimizing the need for their diffusion i to and inside the liquid crystal. (Less)

This study focuses on the mechanism of lean NO2 reduction by propane. In particular the role of isocyanate- and amine species has been studied in transient experiments by in situ Fourier Transform Infrared (FTIR) spectroscopy. The results imply that these species are possible reaction intermediates over acidic HZSM-5.

The formation of solid solutions of cerium oxide with the oxides of calcium, manganese, or neodymium enhances the catalytic activity of cerium oxide for the total oxidation of methane, whereas solid solutions with lead oxide showed an opposite effect. Reasons for this are discussed in terms of oxygen vacancy concentrations and mobilities, local structure configurations, number of oxidation states of dopant, and electron transfer properties. The effects of increased oxygen ion mobility and a more beneficial local structure support the increased catalytic activity for the calcium- and neodymium-doped cerium oxide samples. In addition, a reduced energy for charge transfer from oxygen to cerium supports a higher activity for the calcium-doped sample. The activity data were fitted to an Arrhenius equation, and the apparent activation energies were found to be between 110 and 130 kJ/mol. The particle sizes and the BET areas of the samples were only little affected by the reactor runs, and none of the samples were subjected to phase changes.

A synthesis methodology that decouples the formation of silica particles from their internal mesoordering has been developed. This was possible by employing synthesis conditions that combine fast nucleation and growth of particles with slow silica condensation. The synthesis developed is based on an inorganic silica source and the nonionic block copolymer Pluronic P123 using a synthesis pH of 3 and conditions that result in a stable colloidal suspension. Using a two-step procedure the particles can be first formed and then triggered into developing an ordered internal mesostructure by subsequent addition of silica or Pluronic. This is possible because under the conditions employed the particles are stabilized by relatively weak interactions before the formation of a stable silica network. (C) 2011 Elsevier Inc. All rights reserved.

A crystalline microporous semiconductor |(| K6(H 2O)6| [Sb12O18])3| [Te36] (denoted SBC-1) has been prepared, which consists of 24-ring tubular tellurium units that host 12-ring {Sb12O18} tubular u ...

The polymorph selectivity of a microemulsion-based synthesis solution used for evaporation-induced self-assembly preparation of ordered mesoporous titania films was studied and unexpectedly found to differ from the polymorph selectivity obtained in the films prepared from the reaction solution. While titania nanocrystallites of the rutile phase form in the reaction solution prior to film formation, crystal growth was found to continue after evaporation-induced self-assembly of titania films, resulting in a shift in polymorph selectivity to the anatase phase. Evaporation of solvent and hydrochloric acid during film formation and subsequent aging increases the concentration of the titania precursor and possibly decreases the acidity of the prepared films, both effects that increase the rate of titania condensation, thus promoting the kinetically favoured formation of anatase. The rutile content of the films can be increased by employing an extended reaction time of the synthesis solution prior to the film formation showing that preformed rutile nanocrystallites are retained and incorporated into the titania film during its formation. The crystal growth in the films could be influenced by introducing hydrochloric acid vapour during aging of the formed films, resulting in a decreased formation of anatase nanocrystallites. Such control of the polymorph selectivity in mesoporous titania films is a major advancement towards the synthesis of ordered mesoporous titania films with photocatalytically optimal anatase/rutile ratios and towards the synthesis of pure rutile mesoporous titania.

Mesoporous silica materials made by the use of self-assembled surfactants as templates have attracted a lot of interest in recent years. The number of publications on the topic has increased by a factor of 100 between 1993 and 2003. The vast majority of the papers deal with syntheses from organosilicates, such as tetramethylorthosilicate (TMOS) and tetraethylorthosilicate (TEOS), as the silica source. These alkoxides are convenient as a starting material but they are expensive and the products made from them can only find use in applications where price is not a major issue. This review summarizes the published work on the preparation of mesoporous silica from inorganic sources, such as water glass and silica sol, still using self-assembled surfactants as the template. The use of such raw materials instead of the organosilicates will radically change the production price of the products and may open up completely new fields of application. Much less work has been put into the synthesis of mesoporous silica from these starting materials and relatively little is known about the reaction mechanism. The current understanding is summarized and discussed and comparisons are made with the conventional route that originates from the organosilicates.

Doping carbon materials with transition metal ions can greatly expand their utility, given these metal ions' unique catalytic activity, for example, in oxygen reduction in proton exchange membrane fuel cells. Unlike main group dopants, a counter anion to the metal cation must be selected and this choice has hitherto received little attention for this synthesis method. Herein, we describe the profound effects that the anion has on the resultant iron/nitrogen-doped ordered mesoporous carbons (Fe-OMC). To increase the iron loading and the number of iron-centered catalytically active sites, we selected three iron salts Fe(OAc)2, Fe(OTf)2, and Fe(BF4)2·6H2O, which show greatly enhanced solubility in the liquid carbon precursor (furfurylamine) compared to FeCl3·6H2O. The increased solubility leads to a significantly higher iron loading in the Fe-OMC prepared with Fe(OTf)2, but the increase in performance as cathode catalysts in fuel cells is only marginal. The Fe-OMCs prepared with Fe(OAc)2 and Fe(BF4)2·6H2O exhibited similar or lower iron loadings compared to the Fe-OMC prepared with FeCl3·6H2O despite their much higher solubilities. Most importantly, the different iron salts affect not only the final iron loading, but also which type of iron species forms in the Fe-OMC with different types showing different catalytic activity.