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

Abstract

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 cm−2 has been obtained. The results of this study indicate that PDCs are promising candidates for the synthesis of active non-platinum group metal type catalysts.

Waste Tire Derived Carbon Support for Non-Platinum-Group Metal Catalyst Materials for Oxygen Reduction Reaction in Alkaline Medium

“…II, having a higher ZnCl content, has nearly twice the S and higher microporosity ratio (TABLE III) compared to Fe-DCDA I. The effect of ZnCl on porosity is expected as it is known to increase porosity in carbonaceous catalyst materials (7). The ratio of micropore volume to total pore volume remains similar in the guanidinebased materials, even when synthesis conditions such as precursor ratios and pyrolysis temperature are changed.…”

“…According to the N sorption analysis data (Figure 3), all materials exhibit a moderate specific surface area (S BET = 77-194 g m -2 ) (TABLE III). Carbons synthesized from waste tires (13,16) generally have a lower specific surface area and porosity than, for example, carbide or peat derived carbon NPGM catalysts (6,7). High micro-and mesoporosity is desired in such NPGM materials, since they provide better oxygen mass transport and thus an increase in ORR activity (9,19).…”

“…However, one problem with fuel cells is that they rely heavily on expensive platinum. Non-platinum-group metal (NPGM) catalysts, such as iron and nitrogen co-doped carbon materials, are good contenders to platinum-based catalysts for the oxygen reduction reaction (3,(6)(7)(8)(9)(10). Porous carbon materials are often used as a main precursor to provide electrical conductivity and oxygen mass transport to active sites.…”

Bifunctional Platinum-Free Mixed Metal Oxygen Electrocatalysts Based on Naturally Abundant Peat

“…The platinum-free catalysts were synthesized from naturally abundant welldecomposed Estonian peat acquired from a local peatland. First, the peat was converted into peat-derived carbon (PDC) by using ZnCl 2 as an activating agent and then pyrolyzing the powder at 700 o C for 2 h in Ar (16). Next, the obtained PDC was mixed mechanically with 2,2'-bipyridine (≥99%, Sigma-Aldrich) and different combinations of metal salts in water for 1 h. More specifically, Co(NO 3 ) 2 •6H 2 O (≥99.0%, Sigma-Aldrich), FeSO 4 •7H 2 O (≥99.0%, Sigma-Aldrich), and Ni(NO 3 ) 2 •6H 2 O (99.999%, Sigma-Aldrich) were used in equal amount to produce three catalysts denoted as FeNi/PDC, FeCo/PDC, and FeCoNi/PDC.…”

“…The possibility of modifying peat into platinum-free catalysts and utilizing these materials as oxygen reduction and evolution catalysts in alkaline conditions was investigated in this work. Our previous study involved peat-derived catalysts based on a single metal (16). Herein, different combinations of Fe, Co, and Ni were used to synthesize three mixed metal oxygen electrocatalysts.…”