A high-performance Fe and nitrogen doped catalyst derived from diazoniapentaphene salt and phenolic resin mixture for oxygen reduction reaction

Abstract

A high-performance ORR catalyst has been synthesised by pyrolysis of quaternary nitrogen-containing 4a,8a-diazoniapentaphene dibromide (DAP), phenolic resin and FeBr 2 mixture. The catalyst (Fe/DAP) was characterized by XPS, SEM and TEM analysis. The ORR activity was studied using rotating ring-disk electrode voltammetry (RRDE) and the onset potential of ORR was found to be 0.95 V vs. RHE in 0.5 M H 2 SO 4 solution, which is very close to that of the state-of-the-art Pt/C catalyst. The stability of the catalyst was studied using LD and SSD tests and found to be highly stable even after 11 110 potential-steps in the LD test. The kinetic and mechanistic analyses of the ORR on the catalyst indicate that the ORR, as a whole, follows a 4-electron (parallel) pathway. The relative changes in the nitrogen content after the durability test was estimated using N 1s XPS spectra which may be associated with the activity loss after the durability test. The loss of ORR activity was observed after the acid washing of the catalyst which suggests the role of Fe in the direct 4-electron reduction of O 2 .

One step synthesis of chlorine-free Pt/Nitrogen-doped graphene composite for oxygen reduction reaction

“…The resulting radicals can effectively be adsorbed on the surface [70]. Our Tafel analysis results are in accordance with this picture, as the rate determining step in the high current density region is the first electron transfer in acidic media, while the adsorption of molecular oxygen in alkaline electrolyte [61,62].…”

“…In this case, the rate-determining step is the first chemical step after the first charge transfer step in the pathway of oxygen reduction reaction. However, if the slope is in the range of 120 to 160 mV/decade, then the surface of the electrode is under Langmuir adsorption conditions and the first electron step determines the rate of the oxygen reduction reaction [61,62]. To further reveal the ORR kinetics of the electrodes, rotating disk electrode measurements were performed at different rotation rates.…”

On the use of Nafion® in electrochemical studies of carbon supported oxygen reduction catalysts in aqueous media

“…In accordance with the intended role of the ionomer, its content in the catalyst layer is typically below 20% by weight [14,[24][25][26], i.e., enough to produce the desired surface effect but well below to fill the voids between the support particles and create bulk polymer phase. In some studies, however, the quantities as high as 33% [27], 49% [28], 53% [29] and 56% [30] were used. Such Nafion® amounts are closer to those in PEMFCs and may have had similar effects to those reported for fuel cell Pt catalyst layers [3,6,7,10,[31][32][33][34][35].…”

Tailoring Carbon Nanotube Microsphere Architectures with Controlled Porosity

“…In the low current density (lcd) region, the slope of 60 mV dec −1 is theoretically expected . The results show the slopes for PtFe/CNµS(40%), Pt/CNµS(40%) and commercial Pt/C are 68.5, 76.7, and 71.5 mV dec −1 , indicating a higher electron transfer coefficient for adsorbed oxygen species for PtFe based catalyst than the Pt based catalysts …”