Well-Defined Mo2C Nanoparticles Embedded in Porous N-Doped Carbon Matrix for Highly Efficient Electrocatalytic Hydrogen Evolution
11 Sep 2018-ACS Applied Materials & Interfaces (American Chemical Society)-Vol. 10, Iss: 39, pp 33276-33286
TL;DR: This work presents an easy and cost-effective strategy to prepare molybdenum-based materials with controlled size for electrocatalytic hydrogen evolution, which shows excellent long-term durability in alkaline or acidic electrolyte.
Abstract: On the design of efficient and affordable electrocatalysts for water reduction half reaction, this paper fabricates molybdenum carbide nanoparticles uniformly loaded in highly porous N-doped carbon matrix derived from polyaniline-molybdate monolith with the use of graphitic carbon nitride (g-C3N4) as template The obtained molybdenum carbide-carbon hybrid catalysts (MoC@NCS) exhibit extraordinarily electrochemical hydrogen evolution activity with a small overpotential of 89 and 81 mV to deliver a current density of 10 mA cm–2 in alkaline (10 M KOH) and acidic (05 M H2SO4) medium, respectively, even comparable to noble-metal Pt/C benchmark Specially, MoC@NCS also shows excellent long-term durability in alkaline or acidic electrolyte Furthermore, the obtained carbon matrix (NCS) featuring high content of N dopants and hierarchically porous architecture exhibits high catalytic efficiency for oxygen evolution reaction in alkaline electrolyte For a further step, the obtained NCS coupled with the MoC@NCS,
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TL;DR: The multiscale approaches for promoting the activity and stability of TMPs-based catalysts are elaborately discussed with respect to the intrinsic electronic structure, hybrids, microstructure and working electrode interface and modulated approaches and challenges are instructive for constructing other high-activity energy-related electrocatalysts.
Abstract: As hydrogen has been increasingly considered as promising sustainable energy supply, electrochemical overall water splitting driven by highly efficient non-noble metal electrocatalysts has aroused extensive attention. Transition metal phosphides (TMPs) have demonstrated remarkable electrocatalytic performance, including high activity and robust durability towards hydrogen evolution reaction (HER) in acidic and alkaline as well as neutral electrolytes. In this Review, up-to-date progress of TMP-based HER electrocatalysts is summarized. Various synthesis strategies of TMPs based on selected phosphorus sources are presented, and the reaction mechanisms of HER as well as the contribution of phosphorus in the TMPs to HER activity are briefly discussed. The multiscale approaches for promoting the activity and stability of TMP-based catalysts are discussed with respect to intrinsic electronic structure, hybrids, microstructure, and working electrode interface. Some crucial issues and future perspectives of TMPs are pointed out. These modulated approaches and challenges are also instructive for constructing other high-activity energy-related electrocatalysts.
184 citations
TL;DR: A review of the recent progress made in the fabrication of heterostructure materials toward HER in order to provide an insight into the catalytic properties of heterstructure catalysts is presented in this paper.
Abstract: Searching for a clean and renewable energy system is vital to alleviate the exacerbated environmental pollution problem while addressing the energy dilemma. With clean, renewable and high calorific value features, hydrogen has been identified as an ideal energy carrier to change the global energy structure and accomplish energy conversion in the future. A promising technique to generate hydrogen is water electrolysis, but rationally designing cost-effective and highly efficient catalysts to facilitate their widespread industrialization is still a formidable challenge. In the recent years, heterostructure materials have led to newer types of electrocatalysts owing to their unique physicochemical properties. Constructing heterostructures is regarded as a very important surface engineering aspect for the advancement of HER catalysts. Therefore, we present a review of the recent progress made in the fabrication of heterostructure materials toward HER in order to provide an insight into the catalytic properties of heterostructure catalysts. We start with the introduction of the HER mechanism and the evaluation standards for HER performance. Then, we summarize the synthetic strategies for preparing heterostructure catalysts as well as discussing their catalytic properties for HER. Finally, we discuss the opportunities and challenges for the future development of heterostructure catalysts from the perspectives of material design and synthesis.
140 citations
TL;DR: In this paper, a facile and conventional strategy is developed to fabricate ultrafine Mo-based nanoparticles (MoP, Mo2C and MoS2) dispersed on hierarchically porous carbon nanosheets.
Abstract: Hierarchical nanostructure of intimately coupled transition metal nanoparticles/carbon-based materials can efficiently boost the electrochemical technologies because of the appealingly coupled interaction between different components and the strongly structural advantages. Herein, a facile and conventional strategy is developed to fabricate ultrafine Mo-based nanoparticles (MoP, Mo2C and MoS2) dispersed on hierarchically porous carbon nanosheets. The involved polymer-confinement pyrolysis process can not only efficiently alleviate the aggregation of Mo-based nanoparticles, but also in-situ achieve different Mo-based components on various heteroatoms-doped carbon nanosheets without further post-modification. The hierarchical nanostructure and synergistic effect between carbon substrates and Mo-based nanoparticles enhance the electrochemical performance of the fabricated materials. For instance, the developed MoP@NPCS exhibits outstanding hydrogen evolution performance with high Faradaic efficiency in both acidic and alkaline electrolytes, being one of the impressive catalysts reported to date for hydrogen evolution reaction. This work would inspire the development of interacted carbon-metal functional materials for improving energy-related devices.
122 citations
TL;DR: In this paper, the authors provide a critical review of the current investigations on the heterogeneous catalysts used in the direct dehydrogenation of propane to propylene, and a detailed comparison and discussion of the active sites, catalytic mechanisms, influencing factors, and supports for different types of catalysts.
119 citations
TL;DR: Density functional theory (DFT) calculations suggest that the Mo-N2/C sites can bifunctionally lower the activation energy forLi2S4 to Li2S conversion and the decomposition barrier of Li2 S, accounting for its inherently high activity towards LiPS transformation.
Abstract: The sluggish kinetics of lithium polysulfides (LiPS) transformation is recognized as the main obstacle against the practical applications of the lithium-sulfur (Li-S) battery. Inspired by molybdoenzymes in biological catalysis with stable Mo-S bonds, porous Mo-N-C nanosheets with atomically dispersed Mo-N2/C sites are developed as a S cathode to boost the LiPS adsorption and conversion for Li-S batteries. Thanks to its high intrinsic activity and the Mo-N2/C coordination structure, the rate capability and cycling stability of S/Mo-N-C are greatly improved compared with S/N-C due to the accelerated kinetics and suppressed shuttle effect. The S/Mo-N-C delivers a high reversible capacity of 743.9 mAh g-1 at 5 C rate and an extremely low capacity decay rate of 0.018% per cycle after 550 cycles at 2 C rate, outperforming most of the reported cathode materials. Density functional theory calculations suggest that the Mo-N2/C sites can bifunctionally lower the activation energy for Li2S4 to Li2S conversion and the decomposition barrier of Li2S, accounting for its inherently high activity toward LiPS transformation.
97 citations
References
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TL;DR: A detailed analysis of the structure-activity-pH correlations in the HER process gives an insight on the origin of the pH-dependence for HER, and provides guidance for future HER mechanism studies on non-noble metal-based carbon composites.
Abstract: Hydrogen has been hailed as a clean and sustainable alternative to finite fossil fuels in many energy systems. Water splitting is an important method for hydrogen production in high purity and large quantities. To accelerate the hydrogen evolution reaction (HER) rate, it is highly necessary to develop high efficiency catalysts and to select a proper electrolyte. Herein, the performances of non-noble metal-based carbon composites under various pH values (acid, alkaline and neutral media) for HER in terms of catalyst synthesis, structure and molecular design are systematically discussed. A detailed analysis of the structure-activity-pH correlations in the HER process gives an insight on the origin of the pH-dependence for HER, and provide guidance for future HER mechanism studies on non-noble metal-based carbon composites. Furthermore, this Review gives a fresh impetus to rational design of high-performance noble-metal-free composites catalysts and guide researchers to employ the established electrocatalysts in proper water electrolysis technologies.
1,258 citations
TL;DR: This study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygen-containing intermediates, thus accelerating the overall electrochemical water splitting.
Abstract: To achieve sustainable production of H2 fuel through water splitting, low-cost electrocatalysts for the hydrogen-evolution reaction (HER) and the oxygen-evolution reaction (OER) are required to replace Pt and IrO2 catalysts. Herein, for the first time, we present the interface engineering of novel MoS2/Ni3S2 heterostructures, in which abundant interfaces are formed. For OER, such MoS2/Ni3S2 heterostructures show an extremely low overpotential of ca. 218 mV at 10 mA cm−2, which is superior to that of the state-of-the-art OER electrocatalysts. Using MoS2/Ni3S2 heterostructures as bifunctional electrocatalysts, an alkali electrolyzer delivers a current density of 10 mA cm−2 at a very low cell voltage of ca. 1.56 V. In combination with DFT calculations, this study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygen-containing intermediates, thus accelerating the overall electrochemical water splitting.
1,222 citations
TL;DR: A metal-organic frameworks-assisted strategy for synthesizing nanostructured transition metal carbide nano-octahedrons composed of ultrafine nanocrystallites exhibited remarkable electrocatalytic performance for hydrogen production from both acidic and basic solutions is demonstrated.
Abstract: Electrochemical water splitting has been considered as a promising approach to produce clean and sustainable hydrogen fuel. However, the lack of high-performance and low-cost electrocatalysts for hydrogen evolution reaction hinders the large-scale application. As a new class of porous materials with tunable structure and composition, metal-organic frameworks have been considered as promising candidates to synthesize various functional materials. Here we demonstrate a metal-organic frameworks-assisted strategy for synthesizing nanostructured transition metal carbides based on the confined carburization in metal-organic frameworks matrix. Starting from a compound consisting of copper-based metal-organic frameworks host and molybdenum-based polyoxometalates guest, mesoporous molybdenum carbide nano-octahedrons composed of ultrafine nanocrystallites are successfully prepared as a proof of concept, which exhibit remarkable electrocatalytic performance for hydrogen production from both acidic and basic solutions. The present study provides some guidelines for the design and synthesis of nanostructured electrocatalysts. There is extensive research into non-platinum electrocatalysts for hydrogen evolution. Here, the authors report a molybdenum carbide catalyst, prepared via the carburization of a copper metal-organic framework host/molybdenum-based polyoxometalates guest system, and demonstrate its catalytic activity.
1,194 citations
TL;DR: In this article, the authors proposed a cost-effective molybdenum phosphide that exhibits high activity towards the hydrogen evolution reaction (HER) in both acid and alkaline media even in bulk form.
Abstract: Electrochemical production of hydrogen from water has been directed to the search for non-noble metal based and earth-abundant catalysts. In this work, we propose a novel cost-effective catalyst, molybdenum phosphide that exhibits high activity towards the hydrogen evolution reaction (HER) in both acid and alkaline media even in bulk form. Comparative analysis of Mo, Mo3P and MoP as catalysts for HER clearly indicates that phosphorization can potentially modify the properties of the metal and different degrees of phosphorization lead to distinct activities and stabilities. Theoretical calculations by density functional theory also show that a simple phosphorization of molybdenum to form MoP introduces a good ‘H delivery’ system which attains nearly zero binding to H at a certain H coverage. With the combination of experimental results and theoretical calculations, this work has enlightened a new way of exploring cost-effective catalysts for HER.
1,091 citations
TL;DR: It is demonstrated that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base better than the combination of iridium and platinum as benchmark catalysts.
Abstract: Described here is a method for improving the catalytic activity of an electrocatalyst, comprising subjecting the electrocatalyst to 1-10 galvanostatic lithiation/delithiation cycles, wherein the electrocatalyst comprises at least one transition metal oxide (TMO) or transition metal chalcogenide (TMC). Also described here is an electrocatalyst and a water-splitting device comprising the electrocatalyst.
968 citations