Development of Perovskite Oxide‐Based Electrocatalysts for Oxygen Evolution Reaction

Abstract

solve the energy and environmental problems. The hydrogen production reaction from the electrolysis of water is considered to be the reverse reaction of hydrogen combustion, leading to an energy cycle with zero carbon emission. The electro catalytical water splitting is a green, environmentally friendly, and sustainable way to produce hydrogen. [2] The electrolysis of water includes the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction at the cathode. OER is a four-electron transfer process, which requires high energy to overcome the reaction energy barrier. [3] Therefore, it is of great significance to prepare high-efficiency catalysts to accelerate the OER process. Among many catalysts, noble metal oxides have been considered as the best catalysts for OER, [4] such as IrO 2 and RuO 2 . However, the high cost and low abundance hinder their practical applications on large scale. [3a] Therefore, searching for noble metal-free catalysts with high cost-to-efficiency is necessary.Non-noble transition metals and their compounds have been reported to be active and stable for water oxidation in alkaline solutions. [4] The research on inexpensive and earth-rich alternative catalysts with high activity and long-term stability has been rapidly increasing, especially for 3d-transition metals (i.e., Fe, Co, Ni, etc.)-based oxides, [5] oxyhydrates, [6] perovskites, [7] phosphides, [8] nitrides, [9] selenide, [10] and sulfides. [11] Among various non-precious transition metal-based catalysts, perovskite oxides have been particularly interesting because of their low cost, high flexibility with abundant elemental compositions, and tunable electronic structures. Some of perovskite catalysts showed comparable or even higher catalytic performance to/than the noble metal oxide catalysts, such as IrO 2 and RuO 2 . They have a general formula ABO 3 , where A is an alkaline earth metal (Ba, Sr, etc.), alkali metal (Li, Na, etc.), or rare earth metal atom (La, Pr, etc.) and B is a transition metal atom (Mn, Co, Fe, Ni, etc.) (Figure 1). In the unit cell, the A-position cation is positively charged with 12-fold oxygen coordination, while the B-position cation is positively charged with sixfold oxygen coordination. The substitution of A and/or B cations can modify the physical (e.g., electronic structure), chemical (e.g., oxidation state), and catalytic properties. In addition, a series of perovskite derivatives with different crystal structures, including double perovskites (A 2 B 2 O 6 ), [12] triple perovskites (A 3 B 3 O 9 ), [13] quadruple perovskites (A 4 B 4 O 12 ), [14] and Ruddlesden-Popper perovskites (A n+1 B n O 3n+1 (n = 1, 2, and 3)), [15] further increase the diversity Perovskite oxides are studied as electrocatalysts for oxygen evolution reactions (OER) because of their low cost, tunable structure, high stability, and good catalytic activity. However, there are two main challenges for most perovskite oxides to be efficient in OER, namely less active sites and low electrical conductivity, ...

Hexagonal perovskite Sr6(Co0.8Fe0.2)5O15 as an efficient electrocatalyst towards the oxygen evolution reaction

“…[18][19][20] The perovskite oxides show great flexibility in active sites and oxygen vacancies because of the possible substitutions on the A, B, and O sites, which in turn affect the physical/chemical properties and catalytic performance. 21,22 Although perovskites as OER electrocatalysts have been extensively studied, most of them are limited to cubic-structure perovskites. [23][24][25] There are few research studies on hexagonal-structure perovskites.…”

M4B6X6 as a New Family of High‐Efficient Electrocatalysts: The Role of Surface Reconstruction in Water Oxidization

“…Generally, there are two possible mechanisms for OER: adsorbate-escape mechanism (AEM) and lattice oxygen oxidation mechanism (LOM). [5] The possible active sites for AEM on the surface of M 4 B 6 X 6 can be metal (M) and X (O or F). There are two possible M sites (denoted as lower and upper M) for M 4 B 6 O 6 (Figure 3a), but only one for M 4 B 6 F 6 because all M have the same position and coordination environment.…”

“…[1][2][3] As we are facing increasing challenging issues, such as pollution and energy crisis, the role of catalysis has been extremely emphasized. [4,5] Green-hydrogen technology is considered to be one of the solutions to the sustainable development of our society, where the catalytic process plays a critical role in the production and utilization of hydrogen. Currently, the wide commercialization of hydrogen-based technologies is limited by the low production efficiency and high cost because the catalysts are expensive or less effective.…”

Perovskite With Tunable Active-Sites Oxidation State by High-Valence W for Enhanced Oxygen Evolution Reaction

“…However, their low conductivity and less active sites restrict further development ( Li et al, 2020b ). Strategies to solve these problems include increasing intrinsic activity, exposing more active sites, enhancing electrical conductivity, and so on ( Liu. et al, 202 1, Li et al, 2020 ).…”