Research Progress of Oxygen Evolution Reaction Catalysts for Electrochemical Water Splitting.
TL;DR: In this article, the authors summarized the research progress of anode OER catalysts for hydrogen production by electrochemical water splitting in recent years, for noble metal and non-noble metal catalysts.
Abstract: The development of a low-cost and high-efficiency oxygen evolution reaction (OER) catalyst is essential to meet the future industrial demand for hydrogen production by electrochemical water splitting. Given the limited reserves of noble metals and many competitive applications in environmental protection, new energy, and chemical industries, many studies have focused on exploring new and efficient non-noble metal catalytic systems, improving the understanding of the OER mechanism of non-noble metal surfaces, and designing electrocatalysts with higher activity than traditional noble metals. This Review summarizes the research progress of anode OER catalysts for hydrogen production by electrochemical water splitting in recent years, for noble metal and non-noble metal catalysts, where non-noble metal catalysts are highlighted. The categories are as follows: (1) Transition metal-based compounds, including transition metal-based oxides, transition metal-based layered hydroxides, and transition metal-based sulfides, phosphides, selenides, borides, carbides, and nitrides. Transition metal-based oxides can also be divided into perovskite, spinel, amorphous, rock-salt-type, and lithium oxides according to their different structures. (2) Carbonaceous materials and their composite materials with transition metals. (3) Transition metal-based metal-organic frameworks and their derivatives. Finally, the challenges and future development of the OER process of water splitting are discussed.
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TL;DR: In this article , an alkaline electrolyzer composed of Co-based antiperovskite nitrides (CuNCo3/NF and CoN0.73Co3 /NF) for overall water splitting is designed.
Abstract: Co-based antiperovskite nitrides (CuNCo3/NF and CoN0.73Co3/NF) for overall water splitting are designed. An alkaline electrolyzer composed of CuNCo3/NF and CoN0.73Co3/NF has low cell voltage of 1.53 V at 10 mA cm−2 and maintains remarkable stability.
11 citations
TL;DR: In this paper , the synthesis of vanadium sulfide (VS2) micro-flowered structure via solvent-assisted hydrothermal method using ethylene glycol as an additive in the aqueous-based reaction medium, which has imparted a significant effect on the morphology and the crystallinity of the VS2.
Abstract: Urea oxidation reaction (UOR) assisted water‐splitting is a promising approach for effective treatment of urea‐rich waste‐water at the anode and parallelly generate green‐hydrogen (H2) energy at the cathode via hydrogen evolution reaction (HER). However, facile designing and fabricating robust and cheap electrodes derived from earth‐abundant materials is a great challenge. This work reports the synthesis of vanadium sulfide (VS2) micro‐flowered structure via solvent‐assisted hydrothermal method using ethylene glycol as an additive in the aqueous‐based reaction medium, which has imparted a significant effect on the morphology and the crystallinity of the VS2. In addition, in contrast to the VS2 electrode fabricated in a pure aqueous medium, the ethylene glycol mediated VS2 electrode upon coupling as a cathode and anode in an HER||UOR vs reversible hydrogen electrode (RHE)‐based three‐electrode configuration demonstrates a significantly reduced overall urea decomposition potential of 1.38 V at a current density of 10 mA cm−2 as compared to the conventional water‐splitting of 1.75 V vs RHE. The obtained high‐performance electrocatalytic activity on UOR and HER can be ascribed to the influence of ethylene glycol solvent, particularly on VS2 growth, morphology, and crystallinity, favoring the formation of abundant catalytic sites with facile electrolyte diffusion and electrolysis.
11 citations
TL;DR: In this article , a hexagonal phase structure perovskite oxide was proposed for water electrolysis, which showed promising OER activity with an overpotential of 318 mV at a current density of 10 mA cm-2 and a Tafel slope of only 54 mV dec-1, which is significantly better than the cubic phase structure SrCo 0.8Fe 0.2O3-δ (SCF-C), benchmark noble-metal oxide RuO2 and Ba0.5Sr0.2
Abstract: The high overpotential required for the oxygen evolution reaction (OER)-due to the transfer of four protons and four electrons-has greatly hindered the commercial viability of water electrolysis. People have been committed to the development of alternative precious metal-free OER electrocatalysts, especially electrocatalysts for alkaline media. In this study, we report the application of Sr6(Co0.8Fe0.2)5O15 (SCF-H) perovskite oxide with a hexagonal phase structure in the field of OER electrocatalysis. Synthesized by a simple and universal sol-gel method, the SCF-H perovskite oxide shows prominent OER activity with an overpotential of 318 mV at a current density of 10 mA cm-2 and a Tafel slope of only 54 mV dec-1, which is significantly better than the cubic phase structure SrCo0.8Fe0.2O3-δ (SCF-C), benchmark noble-metal oxide RuO2 and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF). Compared with cubic SCF-C, the hexagonal SCF-H perovskite oxide has abundant surface oxygen species (O22-/O-), a faster charge transfer rate, and a higher electrochemical surface area. In addition, the DFT calculation results show that the center of the O p-band of SCF-H is closer to the Fermi level than that of SCF-C, which leads to the better OER activity of SCF-H. This work finds that the new hexagonal structure perovskite may become a promising OER electrocatalyst.
7 citations
10 Jan 2023
TL;DR: In this article , the Tafel slope values of Ni80 Fe20 OOH catalysts with different loadings at varying rotation rates, hydroxide concentrations, with or without sonication were investigated.
Abstract: A large variety of nickel-based catalysts has been investigated for the oxygen evolution reaction (OER) in alkaline media. However, their reported activity, as well as Tafel slope values, vary greatly. To understand this variation, we studied electrodeposited Ni80 Fe20 OOH catalysts with different loadings at varying rotation rates, hydroxide concentrations, with or without sonication. We show that, at low current density (<5 mA cm-2 ), the Tafel slope value is ≈30 mV dec-1 for Ni80 Fe20 OOH. At higher polarization, the Tafel slope continuously increases and is dependent on rotation rate, loading, hydroxide concentration and sonication. These Tafel slope values are convoluted by non-kinetic effects, such as bubbles, potential-dependent changes in ohmic resistance and (internal) OH- gradients. As best practise, we suggest that Tafel slopes should be plotted vs. current or potential. In such a plot, it can be appreciated if there is a kinetic Tafel slope or if the observed Tafel slope is influenced by non-kinetic effects.
7 citations
TL;DR: In this paper , a simple nitridation route is proposed to design a hybrid material with both ruthenium (Ru) species and mixed metal nitride matrixes (Ru-NiWNx).
6 citations
References
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TL;DR: The biggest challenge is whether or not the goals need to be met to fully utilize solar energy for the global energy demand can be met in a costeffective way on the terawatt scale.
Abstract: Energy harvested directly from sunlight offers a desirable approach toward fulfilling, with minimal environmental impact, the need for clean energy. Solar energy is a decentralized and inexhaustible natural resource, with the magnitude of the available solar power striking the earth’s surface at any one instant equal to 130 million 500 MW power plants.1 However, several important goals need to be met to fully utilize solar energy for the global energy demand. First, the means for solar energy conversion, storage, and distribution should be environmentally benign, i.e. protecting ecosystems instead of steadily weakening them. The next important goal is to provide a stable, constant energy flux. Due to the daily and seasonal variability in renewable energy sources such as sunlight, energy harvested from the sun needs to be efficiently converted into chemical fuel that can be stored, transported, and used upon demand. The biggest challenge is whether or not these goals can be met in a costeffective way on the terawatt scale.2
8,037 citations
TL;DR: This review acquaints some materials for performing OER activity, in which the metal oxide materials build the basis of OER mechanism while non-oxide materials exhibit greatly promising performance toward overall water-splitting.
Abstract: There is still an ongoing effort to search for sustainable, clean and highly efficient energy generation to satisfy the energy needs of modern society. Among various advanced technologies, electrocatalysis for the oxygen evolution reaction (OER) plays a key role and numerous new electrocatalysts have been developed to improve the efficiency of gas evolution. Along the way, enormous effort has been devoted to finding high-performance electrocatalysts, which has also stimulated the invention of new techniques to investigate the properties of materials or the fundamental mechanism of the OER. This accumulated knowledge not only establishes the foundation of the mechanism of the OER, but also points out the important criteria for a good electrocatalyst based on a variety of studies. Even though it may be difficult to include all cases, the aim of this review is to inspect the current progress and offer a comprehensive insight toward the OER. This review begins with examining the theoretical principles of electrode kinetics and some measurement criteria for achieving a fair evaluation among the catalysts. The second part of this review acquaints some materials for performing OER activity, in which the metal oxide materials build the basis of OER mechanism while non-oxide materials exhibit greatly promising performance toward overall water-splitting. Attention of this review is also paid to in situ approaches to electrocatalytic behavior during OER, and this information is crucial and can provide efficient strategies to design perfect electrocatalysts for OER. Finally, the OER mechanism from the perspective of both recent experimental and theoretical investigations is discussed, as well as probable strategies for improving OER performance with regards to future developments.
3,976 citations
TL;DR: The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward a series of key clean energy conversion reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties.
Abstract: A fundamental change has been achieved in understanding surface electrochemistry due to the profound knowledge of the nature of electrocatalytic processes accumulated over the past several decades and to the recent technological advances in spectroscopy and high resolution imaging. Nowadays one can preferably design electrocatalysts based on the deep theoretical knowledge of electronic structures, via computer-guided engineering of the surface and (electro)chemical properties of materials, followed by the synthesis of practical materials with high performance for specific reactions. This review provides insights into both theoretical and experimental electrochemistry toward a better understanding of a series of key clean energy conversion reactions including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward the aforementioned reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties. Also, a rational design of electrocatalysts is proposed starting from the most fundamental aspects of the electronic structure engineering to a more practical level of nanotechnological fabrication.
3,918 citations
TL;DR: The high activity of BSCF was predicted from a design principle established by systematic examination of more than 10 transition metal oxides, which showed that the intrinsic OER activity exhibits a volcano-shaped dependence on the occupancy of the 3d electron with an eg symmetry of surface transition metal cations in an oxide.
Abstract: The efficiency of many energy storage technologies, such as rechargeable metal-air batteries and hydrogen production from water splitting, is limited by the slow kinetics of the oxygen evolution reaction (OER). We found that Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3–δ (BSCF) catalyzes the OER with intrinsic activity that is at least an order of magnitude higher than that of the state-of-the-art iridium oxide catalyst in alkaline media. The high activity of BSCF was predicted from a design principle established by systematic examination of more than 10 transition metal oxides, which showed that the intrinsic OER activity exhibits a volcano-shaped dependence on the occupancy of the 3d electron with an e g symmetry of surface transition metal cations in an oxide. The peak OER activity was predicted to be at an e g occupancy close to unity, with high covalency of transition metal–oxygen bonds.
3,876 citations
TL;DR: In this article, a large database of HO* and HOO* adsorption energies on oxide surfaces was used to analyze the reaction free energy diagrams of all the oxides in a general way.
Abstract: Trends in electrocatalytic activity of the oxygen evolution reaction (OER) are investigated on the basis of a large database of HO* and HOO* adsorption energies on oxide surfaces. The theoretical overpotential was calculated by applying standard density functional theory in combination with the computational standard hydrogen electrode (SHE) model. We showed that by the discovery of a universal scaling relation between the adsorption energies of HOO* vs HO*, it is possible to analyze the reaction free energy diagrams of all the oxides in a general way. This gave rise to an activity volcano that was the same for a wide variety of oxide catalyst materials and a universal descriptor for the oxygen evolution activity, which suggests a fundamental limitation on the maximum oxygen evolution activity of planar oxide catalysts.
2,923 citations