Graphite Carbon-Supported Mo2C Nanocomposites by a Single-Step Solid State Reaction for Electrochemical Oxygen Reduction

Abstract

Novel graphite-molybdenum carbide nanocomposites (G-Mo2C) are synthesized by a typical solid state reaction with melamine and MoO3 as precursors under inert atmosphere. The characterization results indicate that G-Mo2C composites are composed of high crystallization and purity of Mo2C and few layers of graphite carbon. Mo2C nanoparticles with sizes ranging from 5 to 50 nm are uniformly supported by surrounding graphite layers. It is believed that Mo atom resulting from the reduction of MoO3 is beneficial to the immobilization of graphite carbon. Moreover, the electrocatalytic performances of G-Mo2C for ORR in alkaline medium are investigated by cyclic voltammetry (CV), rotating disk electrode (RDE) and chronoamperometry test with 3M methanol. The results show that G-Mo2C has a considerable catalytic activity and superior methanol tolerance performance for the oxygen reduction reaction (ORR) benefiting from the chemical interaction between the carbide nanoparticles and graphite carbon.

Heterogeneous Mo2C/Fe5C2 Nanoparticles Embedded in Nitrogen‐Doped Carbon as Efficient Electrocatalysts for the Oxygen Reduction Reaction

“…Finally, we summarize the onset potential (Figure e) and the average number of electron transfer (Figure f) of different catalysts, indicating that there is a good synergy between the components of the heterogeneous catalyst. Furthermore, the catalytic activity in this study are better than, or similar to those in previously reported works , , , , . The results show that Mo 2 C/Fe 5 C 2 @NC‐800 is a promising catalyst for the ORR.…”

Carbon-Supported Mo2C for Oxygen Reduction Reaction Electrocatalysis

“…ORR onset potential was found to be somewhat more positive at Mo 2 C/CXG (0.89 V) compared to Mo 2 C/CNT (0.81 V) ( Figure 5 ) and comparable to the ORR onset potential at similar materials, such as Mo 2 C nanoparticles embedded in nitrogen-doped porous carbon nanofibers (Mo 2 C/NPCNFs) (0.9 V in 0.1 M KOH) [ 28 ] or Mo 2 C nanowires (0.87 V in 0.1 M KOH) [ 45 ]. Generally, ORR onset potential values for different Mo 2 C-based electrocatalysts were reported to range from 0.75 to 0.91 V [ 25 , 26 , 27 ]. Furthermore, ORR current densities at Mo 2 C/CXG were found to be higher (−2.9 mA cm −2 for Mo 2 C/CXG vs. −1.6 mA cm −2 for Mo 2 C/CNT at 0.6 V at 1600 rpm) with ca.…”

“…90 mV higher half-wave potential (0.71 V for Mo 2 C/CXG vs. 0.62 V for Mo 2 C/CNT), most likely due to its porosity, higher double-layer capacitance, and larger (active) surface area that accelerate the electron transfer at the electrode/electrolyte interface and enhance its performance towards ORR. For further comparison purposes, ORR current densities at Mo 2 C-based electrocatalysts at 0.6 V at 1600 rpm fall in the range from −2.3 to −4.6 mA cm −2 [ 25 , 26 , 27 , 28 ].…”

“…Similar behaviour has been reported for the case of unsupported and carbon-supported Mo 2 C nanowires where average n during ORR was determined to be 3 in 0.7–0.4 V potential range and 4 in 0.3–0 V potential range. Values from 2.1 to 3.8 have been reported for different Mo 2 C-based electrocatalysts [ 25 , 26 , 27 , 28 ].…”

“…Recently, WC, carbon-supported and unsupported, has been explored as an inexpensive, Pt-free electrocatalyst for ORR [ 10 , 20 , 21 , 22 ]. Carbon-supported Mo 2 C has also been reported to show high electrocatalytic activity for hydrogen evolution reaction (HER) [ 23 , 24 ], as well as for ORR [ 25 , 26 , 27 , 28 ]. TMCs’ advantage for applications in fuel cells is their higher abundance (they are several orders of magnitude more abundant than Pt) [ 29 ] and, consequently, lower price as electrocatalysts account for ca.…”