Photoelectrochemical (PEC) water splitting is an attractive strategy for the large‐scale production of renewable hydrogen from water. Developing cost‐effective, active and stable semiconducting ...photoelectrodes is extremely important for achieving PEC water splitting with high solar‐to‐hydrogen efficiency. Perovskite oxides as a large family of semiconducting metal oxides are extensively investigated as electrodes in PEC water splitting owing to their abundance, high (photo)electrochemical stability, compositional and structural flexibility allowing the achievement of high electrocatalytic activity, superior sunlight absorption capability and precise control and tuning of band gaps and band edges. In this review, the research progress in the design, development, and application of perovskite oxides in PEC water splitting is summarized, with a special emphasis placed on understanding the relationship between the composition/structure and (photo)electrochemical activity.
Among the most important classes of materials for the application as electrodes for photoelectrochemical (PEC) water splitting are perovskite oxides. In this Review, recent progress about the development of high‐performance perovskite oxide based electrodes for PEC water splitting is discussed. The design strategies, challenges and perspectives of perovskite oxides as electrodes for PEC water splitting are also presented.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Electrochemical water splitting is a critical energy conversion process for producing clean and sustainable hydrogen; this process relies on low‐cost, highly active, and durable oxygen evolution ...reaction/hydrogen evolution reaction electrocatalysts. Metal cations (including transition metal and noble metal cations), particularly high‐valence metal cations that show high catalytic activity and can serve as the main active sites in electrochemical processes, have received special attention for developing advanced electrocatalysts. In this review, heterogenous electrocatalyst design strategies based on high‐valence metal sites are presented, and associated materials designed for water splitting are summarized. In the discussion, emphasis is given to high‐valence metal sites combined with the modulation of the phase/electronic/defect structure and strategies of performance improvement. Specifically, the importance of using advanced in situ and operando techniques to track the real high‐valence metal‐based active sites during the electrochemical process is highlighted. Remaining challenges and future research directions are also proposed. It is expected that this comprehensive discussion of electrocatalysts containing high‐valence metal sites can be instructive to further explore advanced electrocatalysts for water splitting and other energy‐related reactions.
High‐valence metal cations, including transition metal and noble metal cations, exhibit high catalytic activity and serve as the main active sites in electrochemical processes. This review discusses the design strategies, advances, challenges, and future directions of heterogenous electrocatalysts based on high‐valence metal sites for the application of electrochemical water splitting.
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The development of clean and renewable energy materials as alternatives to fossil fuels is foreseen as a potential solution to the crucial problems of environmental pollution and energy shortages. ...Hydrogen is an ideal energy material for the future, and water splitting using solar/electrical energy is one way to generate hydrogen. Metal‐organic frameworks (MOFs) are a class of porous materials with unique properties that have received rapidly growing attention in recent years for applications in water splitting due to their remarkable design flexibility, ultra‐large surface‐to‐volume ratios and tunable pore channels. This review focuses on recent progress in the application of MOFs in electrocatalytic and photocatalytic water splitting for hydrogen generation, including both oxygen and hydrogen evolution. It starts with the fundamentals of electrocatalytic and photocatalytic water splitting and the related factors to determine the catalytic activity. The recent progress in the exploitation of MOFs for water splitting is then summarized, and strategies for designing MOF‐based catalysts for electrocatalytic and photocatalytic water splitting are presented. Finally, major challenges in the field of water splitting are highlighted, and some perspectives of MOF‐based catalysts for water splitting are proposed.
Metal‐organic frameworks (MOFs) as a class of porous materials have received growing attention these years for their applications in catalyzing the electrocatalytic and photocatalytic water splitting reactions. Recent progress in the exploitation of MOFs toward water splitting reactions is reviewed with highlights in the rational design of highly efficient MOF‐based catalysts. The perspectives for future research are also outlined.
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Perovskite oxides are demonstrated for the first time as efficient electrocatalysts for the hydrogen evolution reaction (HER) in alkaline solutions. A‐site praseodymium‐doped ...Pr0.5(Ba0.5Sr0.5)0.5Co0.8Fe0.2O3–δ (Pr0.5BSCF) exhibits dramatically enhanced HER activity and stability compared to Ba0.5Sr0.5Co0.8Fe0.2O3–δ (BSCF), superior to many well‐developed bulk/nanosized nonprecious electrocatalysts. The improved HER performance originates from the modified surface electronic structures and properties of Pr0.5BSCF induced by the Pr‐doping.
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Perovskite oxides hold great promise as efficient electrocatalysts for various energy‐related applications owing to their low cost, flexible structure, and high intrinsic catalytic activity. However, ...conventional synthetic methods can only obtain perovskite catalysts with large particle sizes, small surface areas, and few morphological features, leading to limited catalytic activity and thus posing a major challenge toward real‐world applications. Reducing the size of bulk perovskites down to the nanosize represents an efficient way to improve the electrocatalytic performance. A comprehensive overview of recent progress in the nanostructuring of perovskites for catalyzing several key reactions in metal–air batteries, water splitting, and solid oxide fuel cells is provided. A range of synthetic protocols for making perovskite nanostructures are summarized, followed by an emphasis on how each method can be tailored to obtain high‐performing perovskite nanocatalysts. These recent advances highlight the enormous potential of nanosized perovskites for facilitating the electrocatalytic reactions. The remaining challenges and future directions are pointed out for the development of next‐generation perovskite‐based nanostructured catalysts.
Nanostructured perovskite oxides have shown great promise as efficient electrocatalysts for various reactions including the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and fuel oxidation reaction. A range of novel nanostructuring methods for making perovskites smaller are reviewed, offering tremendous opportunities for real‐world applications such as metal–air batteries, water splitting, and solid oxide fuel cells.
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High‐Entropy Materials for Water Electrolysis Xu, Xiaomin; Shao, Zongping; Jiang, San Ping
Energy technology (Weinheim, Germany),
November 2022, Volume:
10, Issue:
11
Journal Article
Peer reviewed
Open access
Green hydrogen production by renewables‐powered water electrolysis holds the key to energy sustainability and a carbon‐neutral future. The sluggish kinetics of water‐splitting reactions, namely, ...hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), however, remains a bottleneck to the water electrolysis technology. High‐entropy materials, due to their compositional flexibility, structural stability, and synergy between various elemental components, have recently aroused considerable interest in catalyzing the water‐splitting reactions. Herein, a timely review of the recent achievements is provided in high‐entropy materials for water electrolysis. An overview of different kinds of high‐entropy materials for catalyzing the HER and OER half‐reactions is introduced, followed by a discussion of theoretical and experimental efforts in understanding the fundamental origins of the enhanced catalytic performance observed on high‐entropy catalysts. Various materials design strategies, including control of size and shape, construction of a porous structure, engineering of defect, and formation of hybrid/composite structure, to develop high‐entropy catalysts with improved catalytic performance are highlighted. Finally, the remaining challenges are pointed out and the corresponding perspectives to address these challenges are put forward to promote the development of the research field of high‐entropy water‐splitting catalysts.
High‐entropy materials are emerging as promising water‐splitting electrocatalysts due to their compositional flexibility, structural stability, and synergy between different elemental components. Herein, the recent achievements in water electrolysis catalyzed by high‐entropy materials, covering an overview of material candidates, a discussion of theoretical/experimental insights, a focus on materials design strategies toward improved catalysts, and perspectives on future research directions, are summarized.
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The selective electrochemical CO2 reduction (ECR) to CO in aqueous electrolytes has gained significant interest in recent years due to its capability to mitigate the environmental issues associated ...with CO2 emission and to convert renewable energy such as wind and solar power into chemical energy as well as its potential to realize the commercial use of CO2. In view of the thermodynamic stability and kinetic inertness of CO2 molecules, the exploitation of active, selective, and stable catalysts for the ECR to CO is crucial to promote the reaction efficiency. Indeed, plenty of electrocatalysts for the selective ECR to CO have been explored, of which Ag is known as the most promising electrocatalyst for large‐scale ECR to CO due to several competitive advantages including high catalytic performance, low price, and rich reserves compared with other metal counterparts. To provide useful guidelines for the further development of efficient catalysts for the ECR to CO, a comprehensive summary of the recent progress of Ag‐based electrocatalysts is presented in this Review. Different modification strategies of Ag‐based electrocatalysts are highlighted, including exposure of crystal facets, tuning of morphology and size, introduction of support materials, alloying with other metals, and surface modification with functional groups. The reaction mechanisms involved in these different modification strategies of Ag‐based electrocatalysts are also discussed. Finally, the prospects for the development of next‐generation Ag‐based electrocatalysts are proposed in an effort to facilitate the industrialization of ECR to CO.
A silver lining for CO2: To decrease CO2 concentration in the atmosphere it can be converted into value‐added products such as CO or/and fuels through electrochemical reduction in aqueous electrolytes using renewable energy such as wind and solar power. To achieve this, efficient and robust electrocatalysts are required. Herein, Ag as one the most promising electrocatalysts is reviewed from the viewpoint of different strategies and corresponding reaction mechanisms. Next‐generation Ag‐based electrocatalysts are also proposed.
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The development of oxygen evolution reaction (OER) electrocatalysts remains a major challenge that requires significant advances in both mechanistic understanding and material design. Recent studies ...show that oxygen from the perovskite oxide lattice could participate in the OER via a lattice oxygen-mediated mechanism, providing possibilities for the development of alternative electrocatalysts that could overcome the scaling relations-induced limitations found in conventional catalysts utilizing the adsorbate evolution mechanism. Here we distinguish the extent to which the participation of lattice oxygen can contribute to the OER through the rational design of a model system of silicon-incorporated strontium cobaltite perovskite electrocatalysts with similar surface transition metal properties yet different oxygen diffusion rates. The as-derived silicon-incorporated perovskite exhibits a 12.8-fold increase in oxygen diffusivity, which matches well with the 10-fold improvement of intrinsic OER activity, suggesting that the observed activity increase is dominantly a result of the enhanced lattice oxygen participation.
Poly(N-isopropylacrylamide) (PNIPAM)-based thermosensitive hydrogels demonstrate great potential in biomedical applications. However, they have inherent drawbacks such as low mechanical strength, ...limited drug loading capacity and low biodegradability. Formulating PNIPAM with other functional components to form composited hydrogels is an effective strategy to make up for these deficiencies, which can greatly benefit their practical applications. This review seeks to provide a comprehensive observation about the PNIPAM-based composite hydrogels for biomedical applications so as to guide related research. It covers the general principles from the materials choice to the hybridization strategies as well as the performance improvement by focusing on several application areas including drug delivery, tissue engineering and wound dressing. The most effective strategies include incorporation of functional inorganic nanoparticles or self-assembled structures to give composite hydrogels and linking PNIPAM with other polymer blocks of unique properties to produce copolymeric hydrogels, which can improve the properties of the hydrogels by enhancing the mechanical strength, giving higher biocompatibility and biodegradability, introducing multi-stimuli responsibility, enabling higher drug loading capacity as well as controlled release. These aspects will be of great help for promoting the development of PNIPAM-based composite materials for biomedical applications.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Metal oxides have been extensively applied as heterogeneous catalysts in various chemical processes, including conventional heterogeneous catalysis, photocatalysis, and membrane catalysis. The ...catalytic performance of an oxide heterogeneous catalyst can be affected by its lattice structure, electronic structure, surface properties, bulk defects, and metal-oxygen bond strength. As a catalytic membrane, the catalytic performance of an oxide may also strongly depend on its oxygen-ion diffusion properties. Cation doping has been extensively adopted to tailor, both physically and chemically, the properties of oxide materials, such as lattice structure, electronic structure, lattice defects and diffusion behavior, so as to alter their catalytic performance for various redox reactions. Very recently, anion doping into the oxygen site has emerged as a new strategy for tuning the chemical and physical properties of metal oxides, and thus for regulating their catalytic behavior. Here, a timely review of recent progress in the development of advanced oxide catalysts based on oxygen-site anion doping is provided. Emphasis is given to the effect of doping anions into the metal oxide lattice on the physical and chemical properties, and consequently the performance in various catalytic applications, including the oxidative dehydrogenation of ethane (ODE), oxidative coupling of methane (OCM), photocatalytic reduction of dyes, and ceramic membrane-based oxygen separation. The aim of the current review is to offer some insightful perspectives to guide the development of functional oxide materials based on the anion site doping strategy toward application in heterogeneous catalysis. The knowledge gained here may also be useful for other application fields, such as electrochemical energy storage devices and sensors.
Doping anions, such as fluorine, chlorine, sulfur, carbon or nitrogen elements, into the oxygen sites of metal oxides can alter the catalytic capability of metal oxide catalysts.
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