Double‐Solvent Induced Ultrafine Ruthenium Nanoparticles on Porous Carbon for Highly Efficient Hydrogen Evolution Reaction
TL;DR: In this paper, a double-solvent approach was employed to prepare a ruthenium(Ru)dispersed metal-organic framework composite, which was further pyrolyzed to obtain a novel Ru/C electrocatalyst with a Ru loading of 2.7
Abstract: For hydrogen evolution reaction (HER) in alkaline solution, the state‐of‐the‐art platinum(Pt)‐based electrocatalysts showed a bunch of drawbacks including high cost, poor durability and scarcity, making it essential to develop Pt‐free electrocatalysts. In this work, we employed a double‐solvent approach to prepare a ruthenium(Ru)‐dispersed metal‐organic framework composite, which was further pyrolyzed to obtain a novel Ru/C electrocatalyst with a Ru loading of 2.7 wt %. The target electrocatalyst showed ultrahigh activity for HER in 1 M KOH that outperformed commercial Pt/C catalyst (20 wt %) with an overpotential of 27 mV @ 25 mA cm−2 and 86 mV @ 100 mA cm−2. This work not only provides a promising electrocatalyst for highly efficient HER in alkaline solution, but also offers a double‐solvent strategy for the fabrication of various metal/carbon composites with uniform distribution of ultrafine metal nanoparticles.
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TL;DR: In this paper, a universal avenue to synthesize alloys of Co encapsulated within nitrogen-doped carbon polyhedra along with short carbon nanotubes (CNTs) derived from the metal-organic framework (MOF) was reported.
44 citations
TL;DR: In this paper, Ru-anchored CoP embedded in N-doped porous carbon nanocubes (Ru-CoP/NCs) is successfully prepared for water splitting.
Abstract: Designing and synthesizing stable electrocatalysts with outstanding performance for water splitting is an arduous and urgent task. Herein, Ru-anchored CoP embedded in N-doped porous carbon nanocubes (Ru-CoP/NCs) is successfully prepared. The Ru-CoP/NC reveals superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) properties and stability under alkaline conditions, and the corresponding overpotentials are 22 and 330 mV at 10 mA·cm-2, respectively. The unique N-doped porous carbon nanocube could boost the conductivity, and the electronic structure of CoP can be adjusted by the anchoring of Ru. Therefore, the strong interaction between Ru atoms and CoP improves the hydrogen adsorption on the catalyst, hence boosting the HER/OER performance of the Ru-CoP/NC catalyst. This work provides a facile method to exploit high-performance catalysts for water splitting.
26 citations
TL;DR: In this article, active carbon supported PdZn alloy catalyst was prepared by self-reduction method using zinc acetate as precursor without H2 atmosphere and showed the higher conversion and stability for the hydrogenation of 4-nitrothioanisole than Pd/AC-600 catalyst.
8 citations
TL;DR: In this paper , the porosity, crystallinity, morphology, and electrical conductivity of the nanocomposite are characterized using a self-limiting solution-phase approach.
Abstract: Nanocrystals of a zirconium‐based metal‐organic framework (MOF), UiO‐66, are grown on the surface of the carboxylic acid‐functionalized multi‐walled carbon nanotubes (CNT) at room temperature to synthesize the UiO‐66‐CNT nanocomposites with tunable MOF‐to‐CNT ratios. The porosity, crystallinity, morphology, and electrical conductivity of the nanocomposite are characterized. Spatially dispersed iridium sites are thereafter installed on the defect sites presented within the entire UiO‐66 crystals in these nanocomposites by a self‐limiting solution‐phase approach. The resulting Ir‐functionalized UiO‐66, CNT, and UiO‐66‐CNT nanocomposites are served as the electrocatalysts for water oxidation in acidic aqueous solutions. By utilizing the redox‐hopping pathways to transport electrons within the Ir‐functionalized MOF crystals as well as the electronic conduction between MOF crystals provided by CNT, the nanocomposite with the optimal MOF‐to‐CNT ratio can outperform both the Ir‐functionalized UiO‐66 and CNT. Electrochemical impedance spectroscopy (EIS) is utilized to probe the reaction kinetics occurring on the decorated iridium sites and the transporting behaviors of electrons/ions within these catalytic thin films. For the first time, the electrocatalytic kinetics and the transporting limitations within the MOF‐based thin film can be decoupled with the help of EIS technique. Post‐electrocatalysis characterizations of the nanocomposite after water oxidation are also performed.
3 citations
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TL;DR: A unified theoretical framework highlights the need for catalyst design strategies that selectively stabilize distinct reaction intermediates relative to each other, and opens up opportunities and approaches to develop higher-performance electrocatalysts for a wide range of reactions.
Abstract: BACKGROUND With a rising global population, increasing energy demands, and impending climate change, major concerns have been raised over the security of our energy future. Developing sustainable, fossil-free pathways to produce fuels and chemicals of global importance could play a major role in reducing carbon dioxide emissions while providing the feedstocks needed to make the products we use on a daily basis. One prospective goal is to develop electrochemical conversion processes that can convert molecules in the atmosphere (e.g., water, carbon dioxide, and nitrogen) into higher-value products (e.g., hydrogen, hydrocarbons, oxygenates, and ammonia) by coupling to renewable energy. Electrocatalysts play a key role in these energy conversion technologies because they increase the rate, efficiency, and selectivity of the chemical transformations involved. Today’s electrocatalysts, however, are inadequate. The grand challenge is to develop advanced electrocatalysts with the enhanced performance needed to enable widespread penetration of clean energy technologies. ADVANCES Over the past decade, substantial progress has been made in understanding several key electrochemical transformations, particularly those that involve water, hydrogen, and oxygen. The combination of theoretical and experimental studies working in concert has proven to be a successful strategy in this respect, yielding a framework to understand catalytic trends that can ultimately provide rational guidance toward the development of improved catalysts. Catalyst design strategies that aim to increase the number of active sites and/or increase the intrinsic activity of each active site have been successfully developed. The field of hydrogen evolution, for example, has seen important breakthroughs over the years in the development of highly active non–precious metal catalysts in acid. Notable advancements have also been made in the design of oxygen reduction and evolution catalysts, although there remains substantial room for improvement. The combination of theory and experiment elucidates the remaining challenges in developing further improved catalysts, often involving scaling relations among reactive intermediates. This understanding serves as an initial platform to design strategies to circumvent technical obstacles, opening up opportunities and approaches to develop higher-performance electrocatalysts for a wide range of reactions. OUTLOOK A systematic framework of combining theory and experiment in electrocatalysis helps to uncover broader governing principles that can be used to understand a wide variety of electrochemical transformations. These principles can be applied to other emerging and promising clean energy reactions, including hydrogen peroxide production, carbon dioxide reduction, and nitrogen reduction, among others. Although current paradigms for catalyst development have been helpful to date, a number of challenges need to be successfully addressed in order to achieve major breakthroughs. One important frontier, for example, is the development of both experimental and computational methods that can rapidly elucidate reaction mechanisms on broad classes of materials and in a wide range of operating conditions (e.g., pH, solvent, electrolyte). Such efforts would build on current frameworks for understanding catalysis to provide the deeper insights needed to fine-tune catalyst properties in an optimal manner. The long-term goal is to continue improving the activity and selectivity of these catalysts in order to realize the prospects of using renewable energy to provide the fuels and chemicals that we need for a sustainable energy future.
7,062 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
11 Jan 2017
TL;DR: In this article, the authors investigate progress towards photo-electrocatalytic water-splitting systems, with special emphasis on how they might be incorporated into photoelectrocaralyst systems.
Abstract: Sunlight is by far the most plentiful renewable energy resource, providing Earth with enough power to meet all of humanity's needs several hundred times over. However, it is both diffuse and intermittent, which presents problems regarding how best to harvest this energy and store it for times when the sun is not shining. Devices that use sunlight to split water into hydrogen and oxygen could be one solution to these problems, because hydrogen is an excellent fuel. However, if such devices are to become widely adopted, they must be cheap to produce and operate. Therefore, the development of electrocatalysts for water splitting that comprise only inexpensive, earth-abundant elements is critical. In this Review, we investigate progress towards such electrocatalysts, with special emphasis on how they might be incorporated into photoelectrocatalytic water-splitting systems and the challenges that remain in developing these devices. Splitting water is an attractive means by which energy — either electrical and/or light — is stored and consumed on demand. Active and efficient catalysts for anodic and cathodic reactions often require precious metals. This Review covers base-metal catalysts that can afford high performance in a more sustainable and available manner.
2,369 citations
TL;DR: An overview of recent developments in the non-noble metal catalysts for electrochemical hydrogen evolution reaction (HER) is presented, with emphasis on the nanostructuring of industrially relevant hydrotreating catalysts as potential HER electrocatalysts.
Abstract: Progress in catalysis is driven by society's needs. The development of new electrocatalysts to make renewable and clean fuels from abundant and easily accessible resources is among the most challenging and demanding tasks for today's scientists and engineers. The electrochemical splitting of water into hydrogen and oxygen has been known for over 200 years, but in the last decade and motivated by the perspective of solar hydrogen production, new catalysts made of earth-abundant materials have emerged. Here we present an overview of recent developments in the non-noble metal catalysts for electrochemical hydrogen evolution reaction (HER). Emphasis is given to the nanostructuring of industrially relevant hydrotreating catalysts as potential HER electrocatalysts. The new syntheses and nanostructuring approaches might pave the way for future development of highly efficient catalysts for energy conversion.
1,882 citations
TL;DR: In this article, a review of the recent progress in fabricating metal-organic frameworks (MOFs) and MOF-derived nanostructures for electrochemical applications is presented.
Abstract: Metal–organic frameworks (MOFs) have received a lot of attention because of their diverse structures, tunable properties and multiple applications such as gas storage, catalysis and magnetism. Recently, there has been a rapidly growing interest in developing MOF-based materials for electrochemical energy storage. MOFs have proved to be particularly suitable for electrochemical applications because of their tunable chemical composition that can be designed at the molecular level and their highly porous framework in which fast mass transportation of the related species is favorable. In this review, the recent progress in fabricating MOFs and MOF-derived nanostructures for electrochemical applications is presented. The review starts with an introduction of the principles and strategies for designing targeted MOFs followed by a discussion of some novel MOF-derived structures and their potential applications in electrochemical energy storage and conversion. Finally, major challenges in electrochemical energy storage are highlighted and prospective solutions from current progress in MOF-based nanostructure research are given.
1,250 citations