Recent Progress on Multimetal Oxide Catalysts for the Oxygen Evolution Reaction

Abstract

fossil fuels are being widely researched for the development of a sustainable energy system. Among the various candidates for green energy resources, hydrogen energy has been at the center of attention. [1,2] Hydrogen is both inexhaustible and environmentally friendly, because it can be produced from earth-abundant reactants such as water and methane and because no CO 2 or other toxic products are emitted during its conversion into other energy form such as electricity, respectively. Moreover, hydrogen can exhibit significantly larger energy density compared with other energy sources such as gasoline and coal. The most widely used method of hydrogen production today is steam reforming because of its low cost in the process. [3] Nevertheless, the release of carbon monoxide or carbon dioxide as byproducts in the steam reforming process diminishes the environmental merits of hydrogen energy. Thus, as a possible cleaner alternative, an electrolysis method that involves producing hydrogen by electrochemically splitting water has been extensively investigated. Using one of the most abundant resources, water, the production of hydrogen from it yields only oxygen as a byproduct.In the water electrolysis, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) occur simultaneously, as described by the following equationsIn order for the reaction to proceed, a voltage of 1.23 V is theoretically required between an anode and a cathode. However, an overpotential (represented by the symbol η) should be additionally applied to account for the potential loss resulting from kinetic limitations occurring during the electrochemical reaction. The use of electrocatalysts can lower the overpotential by kinetically facilitating the water-splitting reaction either in HER or OER. Due to the nature of four-electron involving OER, it is generally believed that the OER is much more sluggish than the HER; thus, the development of efficient OER Hydrogen is a promising alternative fuel for efficient energy production and storage, with water splitting considered one of the most clean, environmentally friendly, and sustainable approaches to generate hydrogen. However, to meet industrial demands with electrolysis-generated hydrogen, the development of a low-cost and efficient catalyst for the oxygen evolution reaction (OER) is critical, while conventional catalysts are mostly based on precious metals. Many studies have thus focused on exploring new efficient nonprecious-metal catalytic systems and improving the understandings on the OER mechanism, resulting in the design of catalysts with superior activity compared with that of conventional catalysts. In particular, the use of multimetal rather than single-metal catalysts is demonstrated to yield remarkable performance improvement, as the metal composition in these catalysts can be tailored to modify the intrinsic properties affecting the OER. Herein, recent progress and accomplishments of multimetal catalytic systems, including several important groups of catalysts: layered h...

Recent Advances in Non‐Precious Metal‐Based Electrodes for Alkaline Water Electrolysis

“…In this respect, the electrochemical water splitting reaction‐based technologies are one of the most promising approaches to generate pure hydrogen‐energy . The electrochemical water splitting reaction consists of two primary reactions, hydrogen evolution reaction (HER) at the cathode and oxygen evolution reaction (OER) at the anode . Here, to maximize the energy efficiency of hydrogen production, the electrode engineering, which is required to work at low overpotential with long‐term working stability plays a vital role .…”

Hollow Porous Heterometallic Phosphide Nanocubes for Enhanced Electrochemical Water Splitting

“…Among them, transition metal chalcogenides, carbides, and phosphides have shown potential as highly active and stable catalysts for HER . On the other hand, transition metal oxides and hydroxides have been investigated for catalyzing OER in alkaline electrolytes . Most of the above‐mentioned catalysts function well for either OER or HER.…”

Metal Nanoclusters: New Paradigm in Catalysis for Water Splitting, Solar and Chemical Energy Conversion

“…Many efforts have been undertaken in this regard; up to now, RuO 2 and IrO 2 are among the best electrocatalysts for OER and Pt for HER, exhibiting lowest overpotentials for the respective reactions. Likewise, cost‐effective catalysts, for example, metal sulfides, oxides, phosphides, hydroxides, selenides, and their ternary metal derivatives, have also been developed and evaluated for this purpose . However, their low conductivities, instability, low reaction rates, and high overpotentials severely hamper their large‐scale applications.…”