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

Abstract

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).

Transition Metal-Based Polyoxometalates for Oxygen Electrode Bifunctional Electrocatalysis

“…The most positive value of ORR peak potential (E p ) of 0.632 V was noticed for Fe-POM (Figure 6A), followed by 0.622, 0.558, 0.529, and 0.494 V recorded in the case of Mn-POM, Co-POM, Cu-POM, and Ni-POM, respectively. Herein, obtained peak potential values are in agreement with the literature reports [36][37][38]. All TM-POMs showed ORR peak current density of the same order of magnitude.…”

Silicon nanocages as effective catalysts for oxygen reduction reaction

“…In recent years, the theoretical researchers have examined the various pathways for ORR on surfaces of carbon based nanocatalysts to identify their active positions and suitable sites and to nd the possible pathways from thermodynamic and kinetics perspectives [13][14][15].…”