In situ self-organization of uniformly dispersed Co–N–C centers at moderate temperature without a sacrificial subsidiary metal

Abstract

M-N-C centers have garnered tremendous research attention due to a potential replacement to the Pt- group metal based cathode catalysts and is expected to be the integral part of the...

The Untold Tale of the ORR Polarization Curve

“…For this study, we have considered a batch of four electrocatalysts prepared by pyrolyzing dicyandiamide (DCDA, 200 mg) and Co phthalocyanine (CoPc, 50 mg). The detailed synthesis process is discussed in ref 19. A S7 and S8, and Table 1), it is found that CoP750 is much more effective at facilitating ORR followed by CoP900, CoP600, and CoP380 under identical experimental conditions.…”

“…CoPT's (T = 380/600/750/ 900) were synthesized by the pyrolysis of dicyandiamide (DCDA, 200 mg, mainly a nitrogen and carbon source) and cobalt phthalocyanine (CoP as a cobalt precursor), as discussed in our recent report. 19 The pyrolysis temperatures used are 380, 600, 750, and 900 °C. The temperature ramping rate used was 10 °C/min with a dwell time of 3 h. A physical mixture of DCDA and CoP was prepared by grinding them via a mortar and pestle.…”

“…Following Levich’s seminal discovery of the rotating disk electrode (RDE) and establishment of the mathematical background around 1944, they have been extensively used to monitor/screen the electrochemical processes. , One such important electrochemical processes is the oxygen reduction reaction (ORR), which is considered to be a decisive player in the performance evaluation of fuel cells and metal–air batteries. − Traditionally, the RDE is used to record the ORR polarization curve on any given electrocatalyst prior to its recommendation in electrochemical devices such as fuel cells (FCs) and metal–air batteries (MABs). ,− Interestingly, the RDE allows us to identify kinetic, mixed (kinetic + diffusion), and diffusion-limited regions in ORR polarization curves along with the widely accepted concomitant matrices such as the onset potential ( E onset ), half-wave potential ( E 1/2 ), and diffusion-limited current density ( J d ) for apprising the electrochemical performance of any given electrocatalyst. − An electrocatalyst offering a more positive E onset , E 1/2 , and high J d values is considered to be the most effective. − , Similarly, the matrices used in electrochemical devices such as FCs, as deduced from their respective polarization and power density curves, are the open circuit voltage (OCV), maximum withdrawable power density ( P max ), and associated loss in the ohmic region. ,, …”

“…In the last two decades, the immense growth in the development and design of ecofriendly sustainable energy devices has driven a large number of researchers across the globe (in either developed or developing nations) to find, develop, and design robust and effective oxygen electrocatalysts. − This is obvious from the increase of scientific journals and publications across the publishing houses (Figure ). A careful observation of already published scientific contributions suggests that, in a large fraction of the literature, ORR studies (with matrices like E onset , E 1/2 , and high J d ) have been carried out to claim better prospective oxygen electrocatalysts (Figure a). − ,, In all of these scientific contributions, authors have concluded that the electrocatalysts are suitable for electrochemical devices such as FCs and MABs based on ORR parameters.…”

Design of Hierarchical Oxide‐Carbon Nanostructures for Trifunctional Electrocatalytic Applications

“…[29][30][31] Reports suggest that metal-nitrogen coordination (M-N x ) centers are highly beneficial for ORR and HER. [32][33][34][35][36][37] Transition metal nanoparticles supported on N-doped carbon have been extensively studied for HER. [38][39][40] Metal nanoparticles optimize the surface states of M-N x thereby reducing the energy barrier for water dissociation.…”