Polyacrylamide Microspheres-Derived Fe3C@N-doped Carbon Nanospheres as Efficient Catalyst for Oxygen Reduction Reaction

Abstract

High-performance non-precious metal catalysts exhibit high electrocatalytic activity for the oxygen-reduction reaction (ORR), which is indispensable for facilitating the development of multifarious renewable energy systems. In this work; N-doped carbon-encapsulated Fe3C nanosphere ORR catalysts were prepared through simple carbonization of iron precursors loaded with polyacrylamide microspheres. The effect of iron precursors loading on the electrocatalytic activity for ORR was investigated in detail. The electrochemical measurements revealed that the N-doped carbon-encapsulated Fe3C nanospheres exhibited outstanding electrocatalytic activity for ORR in alkaline solutions. The optimized catalyst possessed more positive onset potential (0.94 V vs. reversible hydrogen electrode (RHE)), higher diffusion limiting current (5.78 mA cm−2), better selectivity (the transferred electron number n > 3.98 at 0.19 V vs. RHE) and higher durability towards ORR than a commercial Pt/C catalyst. The efficient electrocatalytic performance towards ORR can be attributed to the synergistic effect between N-doped carbon and Fe3C as catalytic active sites; and the excellent stability results from the core-shell structure of the catalysts.

Space‐Confined Yolk‐Shell Construction of Fe3O4 Nanoparticles Inside N‐Doped Hollow Mesoporous Carbon Spheres as Bifunctional Electrocatalysts for Long‐Term Rechargeable Zinc–Air Batteries

“…[ 33 ] As shown in the Figure a, the original N/HCSs show the worst ORR activity with the half‐wave potential ( E 1/2 = 0.740 V), and limited current density ( J L = 4.50 mA cm −2 ). After the introduction of Fe 3 O 4 nanoparticles, the ORR activity of these Fe x @N/HCSs increased significantly, and Fe 20 @N/HCSs material exhibit the best performance ( E 1/2 = 0.850 V and J L = 5.750 mA cm −2 ), which is comparable to that of the commercial 20 wt% Pt/C ( E 1/2 = 0.859 V and J L = 5.361 mA cm −2 ), and also is outperforms these of many previously reported yolk‐shell structure ORR electrocatalysts (Table S1, Supporting Information), such as Co NP/NC‐700 ( E 1/2 = 0.80 V and J L = 5.10 mA cm −2 ), [ 44 ] Co‐C@Co 9 S 8 DSNCs ( E 1/2 = 0.83 V and J L = 5.25 mA cm −2 ), [ 45 ] Co/HNCP ( E 1/2 = 0.845 V, Tafel plots = 64 mV dec −1 , and J L = 5.401 mA cm −2 ), [ 46 ] Fe@FeN x /N‐C ( E 1/2 = 0.82 V, Tafel plots = 94.5 mV dec −1 , and J L = 5.25 mA cm −2 ), [ 47 ] Fe 3 C@N/C‐1 ( E 1/2 = 0.815 V, Tafel plots = 68.62 mV dec −1 , and J L = 5.78 mA cm −2 ), [ 48 ] etc. Compared with the Fe 20 @N/HCSs, the limited current density of Fe 30 @N/HCSs become lower obviously, which attributed to the introduction of excess Fe 3 O 4 nanoparticles reduce the electrical conductivity of electrocatalyst (Figure 3e), and the increased ratio of two electron transfer for excess Fe 3 O 4 in the ORR.…”

Low-temperature molten salt synthesis and catalytic mechanism of CoS2/NC as an advanced bifunctional electrocatalyst

“…This, in turn, greatly amplifies the catalytic activity for ORR. 12 Hydrothermal methods and high-temperature sulfidation are commonly used for preparing transition metal sulfide/carbon composites. 13 Yang et al obtained the Fe-CoS 2 /CoS 2 @NC composite material by high-temperature sulfidation of CoFe-PBA obtained by a hydrothermal method.…”

Nanostructured Co3O4 electrocatalyst for OER: The role of organic polyelectrolytes as soft templates

“…In addition, thanks to the large number of negative charges, it is widely employed in wastewater treatment to flocculate insoluble particles and metal precipitation [32]. A recent study shows that polyacrylamide microspheres exhibit metallophylic properties which significantly carried precursor salt with the homogenous distribution [33].…”