Mn ₂ V ₂ O ₇ spiked ball‐like material as bifunctional oxygen catalyst for zinc‐air batteries

Abstract

Summary Hierarchical micro/nanostructures are believed to be magnificent electrocatalyst materials capable of competing with noble metals and the most expensive catalyst materials for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Mn2V2O7‐based hierarchical spiked ball structures (MVO SBs) were synthesized using a simple hydrothermal technique as a bifunctional oxygen catalyst for rechargeable Zn‐air batteries. The linear sweep voltammetry by a rotating disc electrode was used to investigate the ORR and OER properties and their mechanisms, and the charge transfer mechanism was also studied by electrochemical impedance spectroscopy analysis. When compared with platinum with carbon black (Pt/C), the MVO SB catalyst material exhibited comparable ORR and OER properties. Furthermore, the MVO SB material revealed a 4e− transfer pathway in an electrolyte solution. Furthermore, the prepared MVO SB material demonstrated a lower charge‐discharge voltage gap when compared with Pt/C material, which is lower than 180 mV at 45 mA cm−2. The cycling test result of MVO SB catalyst sample revealed excellent cycling stability over 50 charging and discharging cycles (~800 min) than the Pt/C sample (30 cycles [~520 min]). The good catalytic activity and excellent structural stability of the MVO SB material are especially due to the more active sites enhanced by the unique spiked ball‐like morphology and high specific surface area (11.70 m2 g−1) properties. The achieved results suggest that the synthesized catalyst material could be employed as an oxygen catalyst material for rechargeable Zn‐air batteries.

Marigold Flower‐Shaped Metal–Organic Framework Supported Manganese Vanadium Oxide Electrocatalyst for Efficient Oxygen Evolution Reactions in an Alkaline Medium

“…The interplanar lattice fringe spacing is 0.310 nm, which corresponds to the (2 0 0) plane of the monoclinic Mn 2 V 2 O 6 phase. The result is well matched with the obtained XRD patterns [15] . Figure 3D shows the selected area electron diffraction (SAED) pattern produced from the edge section of the nanobelts.…”

“…The full XPS spectra survey scan revealed the existence of Mn, V, O, and C components (Figure S1 in Supporting Information). The high‐resolution Mn 2p XPS spectra (Figure 4B) showed two distinct peaks at 641.5 and 653.8 eV, which corresponded to Mn 2p 3/2 and Mn 2p 1/2 , respectively, resulting from Mn 2+ [15,38] . The high‐resolution V 2p XPS spectra showed two peaks emanating from V 5+ at 517.4 and 524.8 eV, corresponding to V 2p 3/2 and V 2p 1/2 , respectively (Figure 4C).…”

“…The highresolution Mn 2p XPS spectra (Figure 4B) showed two distinct peaks at 641.5 and 653.8 eV, which corresponded to Mn 2p 3/2 and Mn 2p 1/2 , respectively, resulting from Mn 2 + . [15,38] The highresolution V 2p XPS spectra showed two peaks emanating from Chemistry-A European Journal V 5 + at 517.4 and 524.8 eV, corresponding to V 2p 3/2 and V 2p 1/2 , respectively (Figure 4C). [18,39] The high-resolution O 1s XPS spectrum (Figure 4C) was further deconvoluted into two peaks at 530.1 and 531.9 eV, which are attributable to OÀ H groups and lattice oxygen, respectively.…”

“…[12][13][14] Recently, vanadium and manganese-based oxides (VO x and MnO x ) have been the most investigated electrochemical water-splitting applications. [15] Notably, MnO 2 with a supporting structure has attracted a lot of interest due to its large tunnel, which enables effective ion transport. On the other hand, MnO x has low cyclic stability due to its unavoidable disintegration, huge volume expansion, and abrupt phase separation.…”

“…For that reason, a strategy for synthesizing a hybrid electrocatalyst that integrates advanced OER active sites is of great interest for the fabrication of high‐performance functional electrocatalysts [12–14] . Recently, vanadium and manganese‐based oxides (VO x and MnO x ) have been the most investigated electrochemical water‐splitting applications [15] . Notably, MnO 2 with a supporting structure has attracted a lot of interest due to its large tunnel, which enables effective ion transport.…”