Novel Co1-xS/C-3 supported on N-doped ketjen black as an efficient electrocatalyst for oxygen reduction reaction in alkaline media

A Hybrid of the Fe4N-Fe Heterojunction Supported on N-Doped Carbon Nanobelts and Ketjen Black Carbon as a Robust High-Performance Electrocatalyst

Herein, an extremely simple l-alanine-assisted pyrolysis method was proposed for the construction of a novel hierarchically porous hybrid of Fe₄N-Fe supported on N-doped carbon nanobelts and Ketjen black carbon (denoted as Fe₄N-Fe@N-C/N-KB). It has been found that the participation of l-alanine in pyrolysis can dramatically increase the total pyridinic-N/graphitic-N content in Fe₄N-Fe@N-C/N-KB, which is peculiarly conducive to the enhancement of ORR performance. The in-site formation of the Fe₄N-Fe heterojunction via the thermal reduction and decomposition of Fe₃N as well as the introduction of cheap KB can significantly improve the ORR performance. As a result, the activity, durability, and methanol tolerance of this hybrid are comprehensively better than those of commercial 20 wt % Pt/C, promising future applications in practical devices. Density functional theory calculations disclose that the highly improved ORR activity of Fe₄N-Fe@N-C/N-KB also benefits from the favorable electron penetration and excellent electronic conductivity between the Fe₄N nanoparticles and the N-incorporated carbon frameworks.

Facile Synthesis of Low-Cost Copper-Silver and Cobalt-Silver Alloy Nanoparticles on Reduced Graphene Oxide as Efficient Electrocatalysts for Oxygen Reduction Reaction in Alkaline Media

Copper-silver and cobalt-silver alloy nanoparticles deposited on reduced graphene oxide (CuAg/rGO and CoAg/rGO) were synthesized and examined as electrocatalysts for oxygen reduction reaction (ORR) and hydrogen peroxide reduction reaction (HPRR) in alkaline media. Characterization of the prepared samples was done by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction analysis (XRD), and scanning electron microscopy with integrated energy-dispersive X-ray spectroscopy (SEM-EDS). CuAg/rGO and CoAg/rGO nanoparticles diameter ranged from 0.4 to 9.2 nm. The Ag loading was ca. 40 wt.% for both electrocatalysts, with that for Cu and Co being 35 and 17 wt.%, respectively. CoAg/rGO electrocatalyst showed a Tafel slope of 109 mV dec⁻¹, significantly lower than that for CuAg/rGO (184 mV dec⁻¹), suggesting faster ORR kinetics. Additionally, a higher diffusion current density was obtained for CoAg/rGO (−2.63 mA cm⁻²) than for CuAg/rGO (−1.74 mA cm⁻²). The average value of the number of electrons transferred during ORR was 2.8 for CuAg/rGO and 3.3 for CoAg/rGO electrocatalyst, further confirming the higher ORR activity of the latter. On the other hand, CuAg/rGO showed higher peak current densities (−3.96 mA cm⁻²) for HPRR compared to those recorded for CoAg/rGO electrocatalyst (−1.96 mA cm⁻²).