Mn3O4-decorated Co3O4 nanoparticles supported on graphene oxide: Dual electrocatalyst system for oxygen reduction reaction in alkaline medium

Tuning the Electronic Bandgap: An Efficient Way To Improve the Electrocatalytic Activity of Carbon‐Supported Co3O4 Nanocrystals for Oxygen Reduction Reactions

“…Two other components at about 529.2 and 531.3 eV were assigned to lattice oxygen (O latt ) and absorbed oxygen (O abs ), which are associated with the contribution of the Co 3 O 4 phase in these hybrids . The last characteristic component at about 532.6 eV must be attributed to covalent C‐O‐Co groups . This finding is in agreement with results of the C 1s spectra shown in Figure a, which further confirms the existence of C‐O‐Co groups at the interface between Co 3 O 4 and the carbon support in the hybrids.…”

“…This strongly implies that a chemical interaction between the oxide and the GCB in the hybrid may play a key role in the generation of the preferred (111) orientation of the oxide. This chemical interaction between carbon atoms and transition‐metal oxides, such as Co 3 O 4 and Mn 3 O 4 , has been reported in some recently published papers . In our case, the achievement of a preferred orientation along the (111) plane in the spherical Co 3 O 4 nanoparticles in these Co 3 O 4 /GCB hybrids was ascribed to the presence of GCB, which may lead to a strong chemical interaction between the carbon and Co 3 O 4 components in the hybrid.…”

“…However, a new component at around 285.9 eV was also observed for these Co 3 O 4 /GCB hybrids with respect to pure carbon. This component can be ascribed to the formation of covalent C‐O‐Co bonds at the interface, as a result of a chemical interaction between Co 3 O 4 and the carbon support in these hybrids, as demonstrated by recently published results . To further verify the existence of C‐O‐Co bonds, the corresponding O 1s spectra were fitted for the Co 3 O 4 /GCB hybrids and the pure carbon support.…”

A review of transition metal‐based bifunctional oxygen electrocatalysts

“…As previously discussed, MnO x catalysts are prominent ORR electrocatalysts under alkaline media, and therefore, have been extensively studied for alkaline FCs and MABs . Similar to other TMO families, drawbacks of MnO x include poor electronic conductivity and limited ORR activity; and therefore, various strategies such as the design of defected MnO x , the blending with conductive supports such as Ag, Au, and Pd (in which Au > Pt > Pd), and the decoration with other metal or metal oxides (Mn 3 O 4 ‐decorated Co 3 O 4 NPs and Ni‐doped Mn 3 O 4 ) have been proposed to enhance OER, ORR, and bifunctional activities, in which researchers reported that the optimal ORR nature of the Mn 3 II , III O 4 phase, the OER nature of the mixed Mn III,IV oxides, and the synergistic effect between the catalyst and support can all contribute toward outstanding ORR/ORR activities for manganese oxides . Another approach used by researchers to obtain active and stable materials is to design multivalent metal spinels.…”

Enhanced Oxygen Reduction Stability and Activity by Co and N (or O) Interaction in CoO on N‐Doped Carbon Prepared through Spray Pyrolysis

“…In particular, the peaks exhibit a negative shift to ca. 13 cm −1 for CoO/NCs (see the inset), which is attributed to change in the electronic structure derived from higher insertions of nitrogen atoms in the carbon structure or lattice contraction of CoO caused by strong chemical interaction between cobalt oxide and NC at the surface of the catalysts ,…”