Synthesis and Characterization of Cobalt and Nitrogen Co Doped Peat Derived Carbon Catalysts for Oxygen Reduction in Acidic Media

In this study, several peat derived carbons PDC were synthesized using various carbonization protocols. It was found that depending on the carbonization method, carbons with very different surface morphologies, elemental compositions, porosities, and oxygen reduction reaction ORR activities were obtained. Five carbons were used as carbon supports to synthesize Co N PDC catalysts, and five different ORR catalysts were acquired. The surface analysis revealed that a higher nitrogen content, number of surface oxide defects, and higher specific surface area lead to higher ORR activity of the Co N PDC catalysts in acidic solution. The catalyst Co N C 2 ZnCl2 , which was synthesized from ZnCl2 activated and pyrolyzed peat, showed the highest ORR activity in both rotating disk electrode and polymer electrolyte membrane fuel cell tests. A maximum power density value of 210 mW cm2 has been obtained. The results of this study indicate that PDCs are promising candidates for the synthesis of active non platinum group metal type catalyst

Pore wall corrugation effect on the dynamics of adsorbed H 2 studied by in situ quasi elastic neutron scattering Observation of two timescaled diffusion

The self diffusion mechanisms for adsorbed H2 in different porous structures are investigated with in situ quasi elastic neutron scattering method at a temperature range from 50 K to 100 K and at various H2 loadings. The porous structures of the carbon materials have been characterized by sorption analysis with four different gases and the results are correlated with previous in depth analysis with small angle neutron scattering method. Thus, an investigation discussing the effect of pore shape and size on the nature of adsorbed H2 self diffusion is performed. It is shown that H2 adsorbed in nanometer scale pores is self diffusing in two distinguishable timescales. The effect of the pore, pore wall shape and corrugation on the fraction of confined and more mobile H2 is determined and analyzed. The increased corrugation of the pore walls is shown to have a stronger confining effect on the H2 motions. The difference of self diffusional properties of the two H2 components are shown to be smaller when adsorbed in smoother walled pores. This is attributed to the pore wall corrugation effect on the homogeneity of formed adsorbed layer

Carbide derived carbons investigated by small angle X ray scattering Inner surface and porosity vs. graphitization

Small angle X ray scattering SAXS was used to study the nanostructure of Mo2C derived carbon powders CDC synthesized at five different chlorination temperatures. The SAXS intensities have two contributions i a fluctuation contribution from small partially graphitized areas that gives quantitative information about the extent of graphitization, and ii the scattering from the pores. The fluctuation contribution that scales with q2 was quantified in term of a length parameter lR and a disorder parameter that can directly be correlated with the increasing graphitization with increasing temperature. The specific inner surface area of the CDC together with the volume fraction f of the pores increases with the chlorination temperature until 900 C, followed by the significant decrease of both parameters at 1000 C. Further analysis led to the conclusion that CDC obtained at 600 and 700 C are ultramicroporous systems with slit pores having an average size of the order of 0.6 nm. CDC obtained at a high chlorination temperature have pores with sizes between 1 and 3 nm that are of the same size as the walls between the pores. A first comparison demonstrates that the stored energy Emax is directly proportional to the anisometry of the pores embodied in the ratio lc lp obtained by SAX

Peat derived carbon based non platinum group metal type catalyst for oxygen reduction and evolution reactions

For the first time, a novel peat derived carbon PDC was used to synthesize an active non platinum group metal type catalyst for the oxygen reduction reaction ORR and oxygen evolution reaction OER . The obtained catalyst exhibited a smaller specific surface area and was more graphitic compared to a catalyst synthesized identically but using carbide derived carbon CDC instead of PDC. Due to the organic nature of the used peat, the PDC contained numerous additives. In 0.1 M KOH, both the PDC and CDC based catalysts displayed ORR activity comparable to Pt Vulcan. Additionally, equally high OER activities of 1.59 V vs RHE at 10 mA cm amp; 8722;2 were reached for both catalysts studied. Considering the remarkable bifunctional activity of the PDC based catalyst, it can be concluded that PDC is an exceptionally promising carbon support material for ORR and OER catalyst

Cobalt and Nitrogen Co Doped Peat Derived Carbon Based Catalysts for Oxygen Reduction

Using different carbonization protocols, five peat derived carbon materials were synthesized. These carbons have very different surface morphology confirmed by HR SEM and different porosities and pore size distributions obtained by N2 sorption method. The ORR activity of the peat derived carbons also differs significantly in 0.1 M HClO4 solution. Additionally, co doping the peat derived carbons with cobalt and nitrogen enhanced their catalytic activity considerably. The most active ORR catalyst was achieved using the carbon support where the dry milled peat was mixed with ZnCl2 and pyrolyzed in Ar for 2 h at 700 C. Interestingly, the activity of the initial carbon powder does not seem to be a clear indicator of the final activity of the M N C catalysts synthesized from i

Transport properties of H2 confined in carbide derived carbons with different pore shapes and sizes

Hydrogen sorption in highly porous carbon with well defined pores, with three different shapes, and different sizes ranging from sub to nanometers is investigated. Using combined approach of volumetric gas adsorption method and in situ quasi elastic neutron scattering method the relationship between final macroscopic intake properties, details of the local adsorbent structure and the molecular behaviour of confined hydrogen is established. It is shown that sub nanometer pores of spherical and cylindrical shape strongly limit the diffusion of H2, and thus, enhance the H2 storage capability of carbons with well tailored pore structure. In mesoporous carbide derived carbon, the formation of a hydrogen layer with reduced mobility close to the pore walls is observed. With the increase in the amount of confined hydrogen and the occupation of the centre pore area, the mobility of confined hydrogen increases in a jump like fashion. Surprisingly, the increase of hydrogen diffusion is also observed at higher hydrogen loadings, indicating that cooperative H2 H2 interactions might play a rol