Direct Chemical Activation Research Articles

High Porous Activated Carbon from Plastic Waste using Direct Chemical Activation for the Treatment of Organic Dyes in Water

High Porous Activated Carbon from Plastic Waste using Direct Chemical Activation for the Treatment of Organic Dyes in Water

Removal of methylene blue azo dye from aqueous solution using biosorbent developed from floral waste

Aim: The present study was carried out to prepare biosorbent from temple floral waste (Tagetes erecta) by pyrolysis and chemical activation method for removal of methylene blue dye from aqueous solution. Methodology: Floral waste of Tagetes erecta collected from the temples were segregated, washed and dried to form biochar by direct pyrolysis and chemical activation method. Followed by physio-chemical analysis of biosorbents the most efficient biochar was selected for the removal of methylene blue dye from aqueous solution. The adsorbent efficiency and percentage removal of methylene blue dye was studied using various doses of biochar (10, 20, 30, 40, 50, 60, and 70 mg 100 ml-1,), effect of pH (2.0 to 4.0, 6.0 to 8.0, and 10.0 to 12.0) and effect of contact time etc. Results: The comparative physio-chemical analysis of the bio chars suggested that the activated charcoal made from temple flower waste by the direct pyrolysis method showed better performance, with its low moisture content (5.3%), low ash content (4.3%), higher yield, larger surface area, and higher porosity (65.3%) as compared to the biochar obtained from chemical activation. The percent adsorption significantly increased (p<0.05) from 76% to 87.0% on increasing biochar dose from 10.0 to 70.0 mg 100 ml-1. On increasing the pH of the solution from 4.0 to 6.0, Methylene blue removal significantly increased (p<0.05) from 88.0% to 91.0%. Interpretation: It is possible to manage floral waste from temples in a sustainable and environmentally responsible manner by converting it into biochar and using it for the treatment of waste water in order to eliminate hazardous dyes. Key words: Activated carbon, Azo dye, Bioremediation, Biochar, Floral waste, Methylene blue

Ultraporous superactivated hydrochars from food waste: comparing environmental impacts of char impregnation versus direct chemical activation method

Ultraporous superactivated hydrochars from food waste: comparing environmental impacts of char impregnation versus direct chemical activation method

Conversion of the hydrochar recovered after levulinic acid production into activated carbon adsorbents

Levulinic acid production by acid-catalyzed hydrothermal conversion of (ligno)cellulosic biomass generates significant amounts of carbonaceous hydrochar, which is currently considered a final waste. In this work, the hydrochar recovered after the levulinic acid production, was subjected to cascade pyrolysis and chemical activation treatments (by H3PO4 or KOH), to synthesize activated carbons. The pyrolysis post-treatment was already effective in improving the surface properties of the raw hydrochar (Specific Surface Area: 388 m2/g, VP: 0.22 cm3/g, VMESO: 0.07 cm3/g, VMICRO: 0.14 cm3/g), by removing volatile compounds. KOH activation resulted as the most appropriate for further improving the surface properties of the pyrolyzed hydrochar, showing the best surface properties (Specific Surface Area: 1421 m2/g, VP: 0.63 cm3/g, VMESO: 0.10 cm3/g, VMICRO: 0.52 cm3/g), which synergistically makes it a promising system towards adsorption of CO2 (∼90 mg/g) and methylene blue (∼248 mg/g). In addition, promising surface properties can be achieved after direct chemical activation of the raw hazelnut shells, preferably by H3PO4 (Specific Surface Area: 1918 m2/g, VP: 1.34 cm3/g, VMESO: 0.82 cm3/g, VMICRO: 0.50 cm3/g), but this choice is not the smartest, as it does not allow the valorization of the cellulose fraction to levulinic acid. Our approach paves the way for possible uses of these hydrochars originating from the levulinic acid chain for new environmental applications, thus smartly closing the biorefinery loop of the hazelnut shells.

Activated Carbon and Clay Pellets Coated with Hydroxyapatite for Heavy Metal Removal: Characterization, Adsorption, and Regeneration.

In the present work, activated-carbon-containing pellets were preparedby direct chemical activation of sawdust, using clays as a binder. The obtained pellets (ACC) were coated with hydroxyapatite (HAp) nanoparticles (ACC-HAp) to improve adsorption towards Pb(II), Cu(II), Zn(II), and Ni(II). The pellets were characterized by scanning electron microscopy (SEM), by Fourier transform infrared spectroscopy (FTIR), and with a gas sorptometer. The effect of pH, contact time, and initial concentration on adsorption performance was investigated. Additionally, desorption studies were performed, and the regeneration influence on compressive strength and repeated Pb(II) adsorption was investigated. The results showed that, after coating ACC pellets with HAp nanoparticles, the adsorption capacity increased for all applied heavy metal ions. Pb(II) was adsorbed the most, and the best results were achieved at pH 6. The adsorption process followed the pseudo-second-order kinetic model. The adsorption isotherm of Pb(II) is better fitted to the Langmuir model, showing the maximum adsorption capacity of 56 and 47 mg/g by ACC-HAp and ACC pellets, respectively. The desorption efficiency of Pb(II)-loaded ACC-HAp pellets increased by lowering the pH of the acid, resulting in the dissolution of the HAp coating. The best desorption results were achieved with HCl at pH 1 and 1.5. Therefore, the regeneration procedure consisted of desorption, rinsing with distilled water, and re-coating with HAp nanoparticles. After the regeneration process, the Pb(II) adsorption was not affected. However, the desorption stage within the regeneration process decreased the compressive strength of the pellets.

Techno-economic assessment of superactivated hydrochar production by KOH impregnation compared to direct chemical activation

Techno-economic assessment of superactivated hydrochar production by KOH impregnation compared to direct chemical activation

Monodisperse Porous Carbon Nanospheres with Ultra‐High Surface Area for Energy Storage in Electrochemical Capacitors

AbstractHighly porous carbon nanoparticles are very suitable materials for supercapacitor electrodes due to their combination of large surface area for ion adsorption and short pathways for fast ion diffusion. Herein we describe the synthesis of highly porous carbon nanospheres (d=90 nm) by a simple strategy that involves the preparation of monodisperse nanoparticles by the oxidative polymerization of pyrrole, followed by their direct chemical activation with KHCO3. The morphology of the nanospheres is well retained after activation, and the inorganic impurities are removed by a simple washing step with water. The porous nanospheres possess a high electrical conductivity and specific surface areas exceeding 3000 m2 g−1 due to their high content of micropores and small mesopores (<4 nm). Their highly developed and readily available porosity make these materials promising for use as supercapacitor electrodes. In the aqueous 1 M H2SO4 electrolyte, the porous nanospheres reach a capacitance of 262 F g−1 and withstand an ultrahigh current density of 80 A g−1 maintaining a capacitance above 100 F g−1. In the organic 1 M TEABF4/AN and EMImTFSI/AN electrolytes, the nanoparticles reach 175 and 155 F g−1, and the supercapacitors could be cycled up to 50 A g−1 delivering 30 Wh kg−1 at a power density of 20 kW kg−1 and 31 Wh kg−1 at a power density of 31 kW kg−1, respectively. These results demonstrate the potential of these nanoparticles for energy storage applications.

One‐pot emulsion templating for simultaneous hydrothermal carbonization and hydrogel synthesis: porous structures, nitrogen contents and activation

AbstractPorous carbons are of interest for a wide range of advanced‐technology ‘green’ energy applications including fuel cells, hydrogen storage, supercapacitors and batteries. Functional groups, heteroatoms and a more accessible hierarchical porous structure would be advantageous for many of these applications. This paper describes the generation of carbonaceous monoliths with hierarchically porous structures and nitrogen functionalities by using a one‐pot, simultaneous combination of hydrogel synthesis and hydrothermal carbonization (HTC) that involves templating within high internal phase emulsions (HIPEs). A carbon monolith with a density of 0.058 g cm−3, a highly interconnected, bimodal porous structure and an apparent specific surface area (SBET) of 101 m2 g−1 was produced by carbonizing a HTC monolith based on 2‐hydroxyethyl methacrylate (HEMA) at 450 °C. SBET of 1540 m2 g−1 was produced through subsequent chemical activation with ZnCl2 at 700 °C, but the overall residual mass (Rm) was only 9 wt%. Direct chemical activation of the HTC monolith, on the other hand, generated SBET of 1250 m2 g−1 and an overall Rm of 28 wt%, corresponding to a higher apparent surface area per mass of HTC monolith. Carbon monoliths with N/C ratios of 0.09 and 0.07 were achieved using nitrogen‐rich monomers (acrylamide and vinylimidazole, respectively) as compared to the HEMA‐based carbon monolith with an N/C ratio of 0.03. This work demonstrates that the hierarchically porous structures and the chemical structures of these highly porous monoliths can be fine‐tuned by modifying the HIPE composition and/or the processing conditions. © 2021 Society of Industrial Chemistry.

Efficient synthetic approach for nanoporous adsorbents capable of pre- and post-combustion CO2 capture and selective gas separation

The level of CO2 in the atmosphere has increased rapidly due to vast quantities of fossil fuel combustion emissions, and it is accelerating global warming. Hence, pre- and post-combustion CO2 capture and storage (CCS) has become a vital necessity. Cost-effective and efficient nanoporous adsorbents for pre- and post-combustion CO2 capture were developed in this study. The highly porous and oxygen-rich carbon adsorbents were prepared in a facile one-pot process via the direct chemical activation of a molecularly imprinted polymer (MIP) and a MIP composite with activated carbon. The porous carbon adsorbent prepared from the MIP composite had a large specific surface area and specific pore volume of 3010 m2 g−1 and 1.506 cm3 g−1, respectively. Its bimodal pore structure contained micropores and mesopores. This nanoporous carbon adsorbent was rich in electron-dense oxygen presented in a variety of oxygen surface functional groups, which was also advantageous for CCS. These merits afforded selective CO2 adsorption and a high storage capacity under pre- and post-combustion conditions. The efficient carbon adsorbent can be stored 22.1 mmol g−1 and 3 mmol g−1 of CO2 at 25 bar and 1 bar, respectably, which was in the upper range of values reported for porous carbon. Selective CO2 capture by the carbon adsorbents was confirmed by evaluating their selectivity in CO2/CH4, CO2/N2, and CO2/H2 binary gas mixtures at 298 K based on the ideal adsorbed solution theory (IAST). The most effective adsorbent had CO2/H2 (40:60) and CO2/N2 (50:50) selectivity of 534 and 22.6, respectively. The isosteric heat of CO2 adsorption on the porous carbon adsorbents further corroborated the selective CO2 capture.

Comparison of the electrochemical properties of engineered switchgrass biomass-derived activated carbon-based EDLCs

Activated carbon-based electrodes with high surface area were synthesized by direct and indirect chemical activation of switchgrass biomass and its biochar, and decorated with MnO2 in order to enhance and compare the capacitive performance of the fabricated supercapacitors. N2 physisorption, Raman, XPS and SEM techniques were used to examine the differences in the microstructure and surface characteristics of biomass-derived activated carbon samples and MnO2 loaded samples. All fabricated supercapacitors were highly stable and showed high-rate capacitive performance. Direct KOH and H3PO4 activation increased the specific surface area up to 1272 and 1373 m2/g, respectively. As a result, the capacitive performance increased from 50 to 140 F/g for directly KOH activated biomass, and from 49 to 95 F/g for directly H3PO4 activated biomass. MnO2 loading led to an increase in specific capacitance (110 F/g) for the KOH activated biochar, even though no significant effect was observed for the H3PO4 activated biochar. The effectiveness of direct chemical activation of the biomass to enhance the electrochemical performance of the fabricated supercapacitors was demonstrated by comparing it with pseudocapacitive material loading (MnO2) and indirect chemical activation of biochars.

Catalytically Active Carbon From Cattail Fibers for Electrochemical Reduction Reaction.

Catalytically active carbons derived from plant biomass are conducive to the construction of renewable energy source system and utilization of sustainable resources. In this article, natural cattail fibers are used to fabricate porous nitrogen-doped carbon via direct chemical activation and heteroatom modification treatments. The graphene-like sheets from biomass pyrolysis are assembled into three-dimensional carbon frameworks. The chemical activation of KHCO3 generated unique porous structure and N-containing molecules pyrolysis modification provided nitrogen doping atoms. High surface area up to 2,345 m2·g−1 with simultaneous hierarchical pores (from micro to meso and macro) with abundant edge defects are achieved for these carbon materials. These materials have a very large external surface area up to 1,773 m2·g−1. The above strategy exhibits a significant synergistic effect on the improvement of catalytic properties toward hydrogen evolution reaction and oxygen reduction reaction. The small over potentials and Tafel slopes of these catalytically active carbons demonstrate excellent potential applications in renewable energy conversion and storage systems. This research established a new link among environmental improvement, biomass conversion and renewable energy utilization.

Chemical activation of divergent protein tyrosine phosphatase domains with cyanine-based biarsenicals

Strategies for the direct chemical activation of specific signaling proteins could provide powerful tools for interrogating cellular signal transduction. However, targeted protein activation is chemically challenging, and few broadly applicable activation strategies for signaling enzymes have been developed. Here we report that classical protein tyrosine phosphatase (PTP) domains from multiple subfamilies can be systematically sensitized to target-specific activation by the cyanine-based biarsenical compounds AsCy3 and AsCy5. Engineering of the activatable PTPs (actPTPs) is achieved by the introduction of three cysteine residues within a conserved loop of the PTP domain, and the positions of the sensitizing mutations are readily identifiable from primary sequence alignments. In the current study we have generated and characterized actPTP domains from three different subfamilies of both receptor and non-receptor PTPs. Biarsenical-induced stimulation of the actPTPs is rapid and dose-dependent, and is operative with both purified enzymes and complex proteomic mixtures. Our results suggest that a substantial fraction of the classical PTP family will be compatible with the act-engineering approach, which provides a novel chemical-biological tool for the control of PTP activity and the study of PTP function.

Analysis and utilization of temple waste flowers in Coimbatore District.

The present work deals with collection, handling, utilization, and management of the waste flowers that are coming out of the temples in Coimbatore District, Tamilnadu, India. An attempt has been made to provide a current situation and complete analysis of temple waste flowers (TWFs) with suggestions and recommendations. As a part of Clean India, Clean and Green Kovai (Green Coimbatore) mission, this paper gives an idea to reduce the volume of temple waste flowers by converting into activated carbon by direct pyrolysis process and chemical activation with sulfuric acid and phosphoric acid process, respectively. The products were analyzed and compared based on the results of physicochemical parameters including pH, conductivity, moisture content, ash content, volatile content, fixed carbon, bulk density, porosity, specific gravity, water soluble matter, acid soluble matter, iodine number, methylene blue number, yield, and Brunauer-Emmett-Teller (SBET) surface area. The structure, surface morphology, and chemical compositions of carbon were determined by field emission scanning electron microscopy (FeSEM), and energy-dispersive X-ray spectroscopy (EDS), respectively. From the comparison of results, the activated carbon produced from temple waste flowers by direct pyrolysis process is fairly better due to low moisture content, low ash content, better yield, and higher surface area.

Design and preparation of porous carbons from conjugated polymer precursors

Porous nanostructured carbon materials exhibit unique structural features such as high surface area and excellent physicochemical stability and have been of significantly scientific and technological interest because of their vital importance in many energy related applications. Synthetic polymers represent a major class of precursors for developing cutting-edge porous carbons, among which conjugated polymers have emerged as an attractive family of carbon precursors. Distinct from those typical polymer precursors, the robust conjugated structure ensures sufficient framework carbonizability and nanoarchitecture-conserving stability during carbonization process, which is crucial to the successful transformation of designed polymer architectures to finally desired carbon nanostructures. Moreover, heteroatom doping (e.g., N, S, B, and metals) or codoping can be naturally integrated into carbon framework directly by using the heteroatom-containing monomers. Especially, using the newly emerged structurally defined carbon-rich conjugated porous networks as precursors, precise control of compositions and structures of carbon materials becomes possible even at the molecular level. In this review, we will highlight recent strategies to the preparation of porous carbon materials with well-defined porous nanostructures using conjugated polymers as versatile precursors. Beginning with a brief introduction to these precursors, including linear-type conjugated polymers and conjugated porous networks, the synthetic techniques for the fabrication of porous nanostructured carbons by direct templating, self-assembly, template-free, chemical activation, and microwave irritation approaches, will be reviewed. Meanwhile, the sophisticated nanomorphologies, precisely controlled porous structures, and custom-designed functionalities of these conjugated-structure-derived carbons, together made them amenable to diverse task-specific applications, such as electrocatalysis, Li-ion batteries, supercapacitors, and adsorption. Finally, a perspective of the research directions in this field will be presented.

Preparation of chemically activated carbon from waste biomass by single-stage and two-stage pyrolysis

Agricultural waste biomass is often used to produce activated carbon with high specific surface area, high degree of porosity and excellent sorption properties. Many researchers used chemical activation in connection with single-stage or two-stage pyrolysis. Therefore, the aim of this work was to compare both methods. The first method covered direct chemical activation of biomass with a single pyrolytic step. The second procedure consisted of two-stage pyrolysis (after first pyrolysis the char was chemically activated and pyrolysed secondly). Significant differences in morphology, textural properties, organic structure and crystallinity of prepared activated carbons were observed. Activated carbons were tested as a sorbent of Cd2+ from water. Textural analysis showed that the volume of micropores in sample after two-stage pyrolysis was more than four times higher in comparison with single-stage. The value of external surface area related with presence of mesopores was similar for both activated carbons (Sext(single-stage) = 48.1 m2/g; Sext(two-stage) = 50.3 m2/g). The study of ACs sorption capacity was performed as exemplified by cadmium. The experiments evaluated using Langmuir and Freundlich models showed that AC prepared by two-stage pyrolysis has more than three times higher sorption capacity, i.e. 107.5 mg Cd/g comparing to single-stage one, where the sorption capacity of 32.8 mg Cd/g was attained. Thus, loading of environment by cadmium and its uptake by various sorbents are also discussed and compared.

From Azo-Linked Polymers to Microporous Heteroatom-Doped Carbons: Tailored Chemical and Textural Properties for Gas Separation.

Heteroatom-doped porous carbons with ultrahigh microporosity were prepared from a nitrogen-rich azo-linked polymer (ALP-6) as a precursor for gas separation applications. Direct carbonization and chemical activation of ALP-6 with ZnCl2 and KOH were successfully applied to obtain three different classes of porous carbons (ALPDCs). Synthetic processes were conducted at relatively mild temperatures (500-800 °C),which resulted in retention of appreciable levels of nitrogen content (4.7-14.3 wt %). Additionally, oxygen functionalities were found to be present in chemically activated samples. The resultant porous carbons feature a diverse range of textural properties with a predominant microporous nature in common. The highest CO2 uptake value of 5.2 mmol g(-1) at 1 bar and 298 K in ALPDCK600 was originated from well-developed porosity and basic heteroatoms (N and O) on the pore walls. The highest heteroatom doping level (12 wt % nitrogen and 20 wt % oxygen) coupled with the high level of microporosity (84%) for ALPDCK500 led to notable CO2/N2 (62) and CO2/CH4 (11) selectivity values and a high CO2 uptake capacity (1.5 mmol g(-1), at 0.15 bar) at 298 K. This study illustrates the effective use of a single-source precursor with robust nitrogen bonds in combination with diverse carbonization methods to tailor the chemical and textural properties of heteroatom-doped porous carbons for CO2 capture and separation applications.

Potassium hydroxide activation of activated carbon: a commentary

Copyright © Korean Carbon Society http://carbonlett.org Over the years, the furnace has been used as a common heating method to manufacture activated carbon. In a furnace, heat is transferred through conduction and convection. The outer surface of the sample is in contact with the generated heat, which slowly diffuses inwards as a result of the thermal gradient between the surface and the core of the material’s particles. Another method of heating employs microwave irradiation. Even though it is less energyand time-consuming, the microwave method has several critical issues with respect to temperature control and thermal runaway, especially in the scaling-up of the microwave heating process [1]. Generally, the activation of a carbonaceous precursor can be performed through physical (steam, air or CO2) or chemical activation (activators such as ZnCl2, KOH, etc.) or a combination of both. The chemical activation is normally preferable over physical activation since it is a faster process with a lower activation temperature. Moreover, the activated carbon produced via chemical activation usually possesses high specific surface area (as determined by the Brunauer-Emmett-Teller, BET method), good pore development and high carbon yield [2,3]. In recent years, potassium salts such as KOH and K2CO3 have been widely used in the manufacture of low cost activated carbon. It has been found that activated carbon prepared by KOH activation is highly microporous when compared to that produced through ZnCl2 or H3PO4 activation [4-6]. Besides, KOH also enhances the specific surface area and the formation of—OH functional groups on the carbon surface [7]. Over the past 5 years, many advantages of KOH activation have been revealed in the literature [8]. However, the adverse drawbacks of employing KOH have been overlooked in many of the published studies. In this paper, the preparation of activated carbon by KOH activation using conventional heating is reviewed and discussed. The limitations and implications of using KOH in the activation process are highlighted. The selection of appropriate potassium salts for activated carbon preparation is also recommended. The physical preparation of activated carbon is comprised of two major processes, namely, carbonization and activation of the carbonized sample [4]. Chemical activation is a single step process, as both carbonization and activation occur simultaneously at temperatures ranging between 400oC and 700oC, which is lower than that of physical activation [9]. However, in some cases, additional carbonization or a pre-carbonization step is performed to produce char prior to chemical impregnation and activation [5,4,10-13]. Thus, potassium hydroxide activation can be achieved through either direct chemical activation or char-impregnated chemical activation. In direct chemical activation, a selected carbonaceous precursor is first dried overnight to remove moisture and then chemically treated at a desired impregnation ratio (weight of KOH over weight of precursor). The impregnated solid is then heated in a furnace at a specified temperature and time. Carbonization of the precursor is often omitted when the impregnated solid is already suitable for activation. Table 1 exhibits recently developed activated carbon preparation methods using various precursors and KOH activation with conventional heating. From Table 1, it can be seen that DOI: http://dx.doi.org/ DOI:10.5714/CL.2015.16.4.275

Direct Chemical Activation of a Rationally Engineered Signaling Enzyme.

Few chemical strategies for activating enzymes have been developed. Here we show that a biarsenical compound (FlAsH) can directly activate a rationally engineered protein tyrosine phosphatase (Shp2 PTP) by disrupting autoinhibitory interactions between Shp2's N-terminal SH2 domain and its PTP domain. We found that introducing a tricysteine motif at a loop of Shp2's N-SH2 domain confers affinity for FlAsH; binding of FlAsH to the cysteine-enriched loop relieves Shp2's inhibitory interdomain interaction and substantially increases the enzyme's PTP activity. Activation of engineered Shp2 is substrate independent and is observed in the contexts of both purified enzyme and complex proteomes. A chemical means for activating Shp2 could be useful for investigating its roles in signaling and oncogenesis, and the loop-targeting strategy described herein could provide a blueprint for the development of target-specific activators of other autoinhibited enzymes.

Three-dimensional hierarchical porous carbon/graphene composites derived from graphene oxide-chitosan hydrogels for high performance supercapacitors

Graphene-based material, featured with high electrical conductivity, large surface area and good cycling performance, has been considered as one of the most promising materials for supercapacitor. In this work, three-dimensional hierarchical porous carbon/graphene composites (3DHCG) have been synthesized from lyophilized graphene oxide-chitosan (GO-CS) composite hydrogels by the combination of direct carbonization and chemical activation processes. The resulting graphene-based composite has been able to construct a hierarchical pore network with randomly opened macropores and micropores, facilitating fast diffusion to the interior surfaces during rapid charge/discharge process. When compared with the pure carbon, the synthesized 3DHCG composite exhibits remarkably enhanced specific capacitance of 320Fg−1 at a current density of 1Ag−1 in 6M KOH solution, meanwhile maintaining excellent rate performance (with the capacity retention of 70% at 20A/g) and outstanding cycling stability (96% retention after 2000 cycles). The improved electrochemical performances of graphene-based materials represent an alternative promising candidate for the application as supercapacitor electrodes.

Model Non-Precious Metal Catalysts for Oxygen Reduction Reaction: A Bottom-up Approach

Further development of non-precious metal catalysts (NPMCs) synthesized from earth-abundant elements (C, N, transition metal) continues to be challenged by the lack of understanding of the origin of the oxygen reduction reaction (ORR) activity from such complex materials. Current state-of-the-art synthesis methods for NPMCs involve intricate pyrolysis steps producing highly heterogeneous catalytic systems (1, 2). Therefore, a systematic bottom-up approach using model carbon systems needs to be developed for the better understanding of the formation of active sites and the active site identification. Recently, we have reported a novel approach for the incorporation of nitrogen heteroatoms into the graphitic carbon structure of liquid-phase exfoliated graphite (3). This approach utilizes high-flux energetic neutral atom beam technology (ENABLE) to incorporate nitrogen heteroatoms via direct chemical activation overcoming thermal activation barriers. Our preliminary results have identified a relationship between the type of nitrogen species doped and the substrate temperature (Figure 1). However, although improved onset potential for the ORR was observed from thin films doped with 13 at.% nitrogen (87% graphitic), the electrocatalytic activity in acid electrolyte is still poor. The work to be presented in this talk represents the continuation of our efforts to understand the role of each component in NPMCs, this time with the addition of transition metals, Fe and/or Co, prior to nitrogen doping. Electrochemical studies will be performed in both acid and alkaline electrolytes to better understand the different reaction mechanism in both environments.