Role of the Morphology and Surface Planes on the Catalytic Activity of Spinel LiMn_1.5Ni_0.5O₄for Oxygen Evolution Reaction

Abstract

The electrocatalytic activity of the spinel oxide LiMn 1.5 Ni 0.5 O 4 with different morphologies (cubic, spherical, octahedral, and truncated octahedral) has been investigated for the oxygen evolution reaction (OER) in alkaline solutions that is of interest for metal−air batteries. The OER activity increases in the order truncated octahedral < cubic < spherical < octahedral, despite a larger surface area (2.9 m 2 g −1 ) for the spherical sample compared to nearly similar surface areas (0.3−0.7 m 2 g −1 ) for the other three samples. The high activity of the octahedral sample is attributed to the regular octahedral shape with low-energy {111} surface planes, whereas the lowest activity of the truncated octahedral sample is attributed to the high-energy {001} surface planes. The octahedral sample also exhibits the lowest Tafel slope of 70 mV dec −1 with the highest durability whereas the truncated octahedral sample exhibits the highest Tafel slope of 120 mV dec −1 with durability similar to the cubic and spherical samples. The study demonstrates that the catalytic activities of oxide catalysts could be tuned and optimized by controlling the surface morphologies/planes via novel synthesis approaches.

Electrochemical Water Splitting by Pseudo‐spinel, Disordered and Layered Lithium Nickel Oxides: Correlation between Structural Motifs and Catalytic Properties

“…To understand the OER activities further, it is tempting to further evaluate their catalytic performance using a Tafel plot under alkaline conditions. The Tafel slope of L ‐LiNiO 2 is 88 mV dec −1 , close to those in previous reports of cubic LiMn 1.5 Ni 0.5 O 4 (120 mV dec −1 ) as shown in Figure b . The parameters to describe the activity of the Ni‐based catalysts are summarized in Table S2.…”

“…As we all known, layered lithium nickel oxide is well‐known cathode materials for Li ion batteries owing to lower cost and higher energy density. Recently, the layered lithium transition metal oxides, such as LiCoO 2 , LiCoPO 4 , LiCo 1− x Ni x O 2 , LiNi 1− x Mn x O 2 , and LiCo 1− x Mn x O 2 , have also exhibited high catalytic activity for OER in alkaline electrolytes . However, the pure nickel based layered lithium materials without doping other elements have not been detailed studied as highly activity electrocatalyst for OER to data.…”

A review of transition metal‐based bifunctional oxygen electrocatalysts

“…For example, Co x Mn 3− x O 4 catalysts were recently prepared using different reducing agents to control the crystallographic structure such as cubic and tetragonal phases (Figure a,b) based on the report that crystallographic modification can accommodate the tuning of catalytic activity in which the cubic phase reportedly displayed significantly improved ORR and OER activities as compared with the tetragonal phase. The chemical composition of the as‐synthesized materials can also influence the coordination sites, surface structures, pore sizes, and surface areas of catalysts, and the composition of catalysts have a great impact on the oxidation/reduction potential of neighboring elements and the enhancement of the activity and selectivity of the product …”

LaTi0.65Fe0.35O3− nanoparticle-decorated nitrogen-doped carbon nanorods as an advanced hierarchical air electrode for rechargeable metal-air batteries

“…Recently much attention has been paid towards the development of efficient cathode catalysts, including precious metals, porous carbon-based materials, transition-metal oxides (e.g., perovskites, spinels, and pyrochlores), as potential candidates for bifunctional oxygen electrode in metal-air batteries [5][6][7][8][9][10][11][12]. Among them, perovskite-based materials have been intensively explored due to their fascinating physico-chemical properties, high electrochemical stability, cost-effectiveness, and environmental friendliness [13][14][15][16].…”