MOF-Derived Bifunctional Cu3 P Nanoparticles Coated by a N,P-Codoped Carbon Shell for Hydrogen Evolution and Oxygen Reduction

Bimetal-organic framework MIL-53(Co-Fe): an efficient and robust electrocatalyst for the oxygen evolution reaction

Rationally designing high-efficiency catalysts for the oxygen evolution reaction (OER) is extremely important for developing sustainable energy technologies, but remains a major research challenge. In this paper, a Co/Fe-imidazole-based bimetal-organic framework nanosheet array grown on a nickel foam [MIL-53(Co-Fe)/NF] was prepared via a facile solvothermal process. Surprisingly, MIL-53(Co-Fe)/NF shows excellent OER activity with overpotential as low as 262 mV at 100 mA cm^-2, much lower than those of the single metal-based MOFs, and even comparable to that of the precious RuO₂. The results indicate that the synergetic effect of co-doped Fe and Co makes a crucial contribution to the high activity of the bimetal-based MOF catalyst. Additionally, this catalyst also displays outstanding long-term electrochemical durability for at least 80 h.

In situ modulation of silica-supported MoO2/Mo2C heterojunction for enhanced hydrogen evolution reaction

Hydrogen being a promising source of clean energy, the production of hydrogen using electrocatalysis and the development of carbon-neutral energy conversion technologies are crucial.

RuNi Nanoparticles Embedded in N-Doped Carbon Nanofibers as a Robust Bifunctional Catalyst for Efficient Overall Water Splitting

Developing high-performance, low-cost, and robust bifunctional electrocatalysts for overall water splitting is extremely indispensable and challenging. It is a promising strategy to couple highly active precious metals with transition metals as efficient electrocatalysts, which can not only effectively reduce the cost of the preparation procedure, but also greatly improve the performance of catalysts through a synergistic effect. Herein, Ru and Ni nanoparticles embedded within nitrogen-doped carbon nanofibers (RuNi-NCNFs) are synthesized via a simple electrospinning technology with a subsequent carbonization process. The as-formed RuNi-NCNFs represent excellent Pt-like electrocatalytic activity for the hydrogen evolution reaction (HER) in both alkaline and acidic conditions. Furthermore, the RuNi-NCNFs also exhibit an outstanding oxygen evolution reaction (OER) activity with an overpotential of 290 mV to achieve a current density of 10 mA cm-2 in alkaline electrolyte. Strikingly, owing to both the HER and OER performance, an electrolyzer with RuNi-NCNFs as both the anode and cathode catalysts requires only a cell voltage of 1.564 V to drive a current density of 10 mA cm-2 in an alkaline medium, which is lower than the benchmark of Pt/C||RuO2 electrodes. This study opens a novel avenue toward the exploration of high efficient but low-cost electrocatalysts for overall water splitting.

MOF-derived electrocatalysts for oxygen reduction, oxygen evolution and hydrogen evolution reactions

The morphology and composition design of MOF-derived carbon-based materials and their applications for electrocatalytic ORR, OER and HER are reviewed.

Cu3P nanoparticle-reduced graphene oxide hybrid: an efficient electrocatalyst to realize N2-to-NH3 conversion under ambient conditions

For electrocatalytic N₂-to-NH₃ fixation, a Cu₃P-rGO nanohybrid affords a Faradic efficiency of 10.11% with a NH₃ yield of 26.38 μg h⁻¹ mg_cat.⁻¹ at −0.45 V vs. RHE.

2D organ-like molybdenum carbide (MXene) coupled with MoS2 nanoflowers enhances the catalytic activity in the hydrogen evolution reaction

Our work introduces an emerging route for the synthesis of MoS₂ nanoflowers decorating organ-like Mo₂CT_x MXene. This effective synthesis strategy of MoS₂@Mo₂CT_x nanohybrid structure can shed some light on energy-related applications.

A review of recent work on using metal–organic frameworks to grow carbon nanotubes

In this review, we summarize catalysts and synthetic strategies for the synthesis of MOF-derived CNT-based composite materials.

The preparation of NiO/Ni–N/C nanocomposites and its electrocatalytic performance for methanol oxidation reaction

The NiO/Ni–N/C nanocomposites were prepared through hydrothermal method and further carbonization. The NiO/Ni–N/C₅₀₀ displays the highest MA (1043 mA mg_Ni⁻¹) and SA (18.57 mA cm⁻²) for methanol oxidation reaction.

A highly efficient electrochemical oxygen evolution reaction catalyst constructed from a S-treated two-dimensional Prussian blue analogue

A synthesized S-CoFe-PBA/CFP electrode exhibited remarkable electrocatalytic performance and durability toward the OER under alkaline conditions.

Precursor-Transformation Strategy Preparation of CuPx Nanodots-Decorated CoP3 Nanowires Hybrid Catalysts for Boosting pH-Universal Electrocatalytic Hydrogen Evolution

The development of earth-abundant, low cost, and versatile electrocatalysts for producing hydrogen from water electrolysis is still challenging. Herein, based on high hydrogen evolution reaction (HER) activity of transition metal phosphides, a CoP₃ nanowire decorated with copper phosphides (denoted as CuP_x ) nanodots structures synthesized through a simple and easily scalable precursor-transformation strategy is reported as a highly efficient HER catalyst. By decorating with CuP_x nanodots, the optimized CoP₃ nanowires electrode exhibits excellent catalytic activity and long-term durability for HER in alkaline conditions, achieving a low overpotential of 49.5 mV at a geometrical catalytic current density of 10 mA cm^-2 with a small Tafel slope of 58.0 mV dec^-1 , while also performing quite well in neutral and acidic media. Moreover, its overall performance exceeds most of the reported state-of-the-art catalysts, especially under high current density of 100 mA cm^-2 , demonstrating its potential as a promising versatile pH universal electrocatalyst for efficient water electrolysis. These results indicate that the incorporation of earth-abundant stable element copper can significantly enhance catalytic activity, which widens the application range of copper and provides a new path for design and selection of HER catalysts.

MOF-derived cobalt-nickel phosphide nanoboxes as electrocatalysts for the hydrogen evolution reaction

The development of high-efficiency nonprecious electrocatalysts based on inexpensive and Earth abundant elements is of great significance for renewable energy technologies. Group VIII transition metal phosphides (TMPs) gradually stand out due to their intriguing properties including low resistance and superior catalytic activity and stability. Herein, we adopt a unique MOF-derived strategy to synthesize transition metal phosphide nanoboxes which can be employed as electrocatalysts for the hydrogen evolution reaction. During this process, we converted a Co-MOF to a CoNi-MOF by ion exchange and low-temperature phosphating to achieve CoNiP nanoboxes. The CoNiP nanoboxes can reach a current density of 10 mA cm^-2 at a low overpotential of 138 mV with a small Tafel slope of 65 mV dec^-1.

A Hydrangea-Like Superstructure of Open Carbon Cages with Hierarchical Porosity and Highly Active Metal Sites

Carbon micro-/nanocages have attracted great attention owing to their wide potential applications. Herein, a self-templated strategy is presented for the synthesis of a hydrangea-like superstructure of open carbon cages through morphology-controlled thermal transformation of core@shell metal-organic frameworks (MOFs). Direct pyrolysis of core@shell zinc (Zn)@cobalt (Co)-MOFs produces well-defined open-wall nitrogen-doped carbon cages. By introducing guest iron (Fe) ions into the core@shell MOF precursor, the open carbon cages are self-assembled into a hydrangea-like 3D superstructure interconnected by carbon nanotubes, which are grown in situ on the Fe-Co alloy nanoparticles formed during the pyrolysis of Fe-introduced Zn@Co-MOFs. Taking advantage of such hierarchically porous superstructures with excellent accessibility, synergetic effects between the Fe and the Co, and the presence of catalytically active sites of both metal nanoparticles and metal-N_x species, this superstructure of open carbon cages exhibits efficient bifunctional catalysis for both oxygen evolution reaction and oxygen reduction reaction, achieving a great performance in Zn-air batteries.

Nanobundles of Iron Phosphide Fabricated by Direct Phosphorization of Metal-Organic Frameworks as an Efficient Hydrogen-Evolving Electrocatalyst

Transition-metal-based phosphides (TMPs) have been considered as attractive electrocatalysts for water splitting due to their earth-abundance and remarkable catalytic activity. As a representative type of precursors, metal-organic frameworks (MOFs) provide ideal plateaus for the design of nanostructured TMPs. In this work, the hierarchically structured iron phosphide nanobundles (FeP-500) were fabricated by one-step phosphorization of an iron-based MOF (MET(Fe)) precursor. The derived FeP-500 nanobundles were constructed by quasi-paralleled one-dimensional nanorods with uneven surface, which provided channels for electrolyte penetration, mass transport, and effective exposure of active sites during the water-splitting process. With the addition of conductive Super P, the obtained FeP-500-S exhibited a good electrocatalytic performance towards the hydrogen evolution reaction in alkaline electrolyte (1 mol L^-1 KOH). Furthermore, to investigate the influence of secondary metal doping, a series of isoreticular MOF precursors and bimetallic TMPs were fabricated. The results indicated that the catalytic performance is structure dominated.

Hierarchical Nanoporous V2O3 Nanosheets Anchored with Alloy Nanoparticles for Efficient Electrocatalysis

Exploring low-cost bifunctional electrocatalysts for efficient water splitting still faces arduous challenges. Herein, a general and straightforward method is developed to prepare 3D hierarchical nanoporous V₂O₃ nanosheets anchored with different alloy nanoparticles by adopting metal-ion-doped zinc-vanadium (oxy)hydroxides as precursors. To demonstrate this concept, we produced nanoporous V₂O₃ nanosheets dotted with NiFe alloy nanoparticles through high-temperature reduction and free corrosion. Due to the increased number of active sites, accelerated mass transfer originating from the designed nanoporous architecture, and the metallic property of the V₂O₃ matrix, the NiFe@V₂O₃ hybrid exhibits excellent electrocatalytic performances for both oxygen and hydrogen evolution reactions. When adopting the NiFe@V₂O₃ as a bifunctional electrode for overall water splitting, it only requires a cell voltage of 1.56 V to reach 10 mA cm^-2. This work provides a general and practical way to prepare high-efficient and low-cost electrocatalysts.

Uniform copper-cobalt phosphides embedded in N-doped carbon frameworks as efficient bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries

The development of efficient and abundant transition metal bifunctional electrocatalysts is crucial in sustainable energy utilization. Copper-cobalt bimetallic composites exhibit excellent electrochemical performance but the agglomeration of nanoparticles and phase separation cannot be avoided in high temperature pyrolysis. Herein, Cu(ii) ions are introduced into Co-based zeolitic imidazolate frameworks (ZIF-67) by a polymer-coating method to synthesize copper-cobalt bimetallic composite phosphides (CuCoP). After further pyrolysis and phosphidation, the uniform CuCoP nanoparticles are embedded into N-doped carbon frameworks (CuCoP-NC) derived from organic ligands. CuCoP-NC possesses unique hollow structure, rich pores in the carbon framework and large specific surface areas. At an optimal carbonization temperature of 700 °C, CuCoP-NC-700 exhibits admirable electrocatalytic performance such as high onset potentials (0.978 V vs. reversible hydrogen potential (RHE) in alkaline media and 0.801 V vs. RHE in acidic media), large limiting current densities, long-term stability and eximious resistance to methanol poisoning towards the oxygen reduction reaction (ORR) in both alkaline and acidic media and a low overpotential of 337 mV at 10 mA cm^-2 towards the oxygen evolution reaction (OER). Moreover, CuCoP-NC-700 is assembled into a Zn-air battery and presents a higher power density (116.5 mW cm^-2) and stability compared to Pt/C.

Synergic Catalysts of Polyoxometalate@Cationic Porous Aromatic Frameworks: Reciprocal Modulation of Both Capture and Conversion Materials

Compositional catalysts based on porous supports and incorporated catalytic nanoparticles have achieved great successes during the past decades. However, rational design of synergic catalysts and modulating the interactions between functional supports and catalytic sites are still far from being well developed. In this work, aiming at overcoming the difficulties of comprehensive screening of porous supports and correspondingly matched catalytic sites, a cationic porous aromatic framework as a capturing platform and polyoxometalate anions as conversion materials are separately designed, and their combination is modularly controlled. The resulting composites show higher catalytic activities than the corresponding conversion sites themselves. Notably, the resulting composites uncommonly exhibit increased surface area and enlarged pore openings after the incorporation of nanoparticles, and lead to the promotion of mass transfer within the porous supports. The emergence of a hierarchical structure with increased surface area induced by guest loading is desired in heterogeneous catalysis. The reciprocal modulation of both capture and conversion materials results in enhanced conversion and increased reaction rate, indicating the successful preparation of synergic catalysts by this separate design approach.

Selective Cellulose Hydrogenolysis to Ethanol Using Ni@C Combined with Phosphoric Acid Catalysts

Ethanol is an important bulk chemical with diverse applications. Biomass-derived ethanol is traditionally produced by fermentation. Direct cellulose conversion to ethanol by chemocatalysis is particularly promising but remains a great challenge. Herein, a one-pot hydrogenolysis of cellulose into ethanol was developed by using graphene-layers-encapsulated nickel (Ni@C) catalysts with the aid of H₃ PO₄ in water. The cellulose was hydrolyzed into glucose, which was activated by forming cyclic di-ester bonds between the OH groups of H₃ PO₄ and glucose, promoting ethanol formation under the synergistic hydrogenation of Ni@C. A 69.1 % yield of ethanol (carbon mole basis) was obtained, which is comparable to the theoretical value achieved by glucose fermentation. An ethanol concentration of up to 8.9 wt % was obtained at an increased cellulose concentration. This work demonstrates a chemocatalytic approach for the high-yield production of ethanol from renewable cellulosic biomass at high concentration.

Heterostructure engineering of Co-doped MoS2 coupled with Mo2CTx MXene for enhanced hydrogen evolution in alkaline media

The hydrogen evolution reaction (HER) in alkaline media is key for the cathodic reaction of electrochemical water splitting, but it suffers sluggish kinetics due to the slow water dissociation process. Here, we present a simple strategy to enhance the HER activity in alkaline media by engineering Co-doped MoS2 coupled with Mo2CTx MXene. The improved HER activity might be ascribed to the synergistic regulation of water dissociation sites and electronic conductivity. Co doping could effectively regulate the electronic structure of MoS2 and further improve the intrinsic activity of the catalyst. Mo2CTx MXene served as both the active and conductive substrate to facilitate electron transfer. As a result, the Co-MoS2/Mo2CTx nanohybrids showed dramatically enhanced HER performance with a low overpotential of 112 mV at a current density of 10 mA cm-2 and exhibited excellent long-term stability in alkaline media.

Ambient Fast Synthesis and Active Sites Deciphering of Hierarchical Foam-Like Trimetal-Organic Framework Nanostructures as a Platform for Highly Efficient Oxygen Evolution Electrocatalysis

Metal-organic frameworks (MOFs) have attracted tremendous interest due to their promising applications including electrocatalysis originating from their unique structural features. However, it remains a challenge to directly use MOFs for oxygen electrocatalysis because it is quite difficult to manipulate their dimension, composition, and morphology of the MOFs with abundant active sites. Here, a facile ambient temperature synthesis of unique NiCoFe-based trimetallic MOF nanostructures with foam-like architecture is reported, which exhibit extraordinary oxygen evolution reaction (OER) activity as directly used catalyst in alkaline condition. Specifically, the (Ni₂ Co₁ )_0.925 Fe_0.075 -MOF-NF delivers a minimum overpotential of 257 mV to reach the current density of 10 mA cm^-2 with a small Tafel slope of 41.3 mV dec^-1 and exhibits high durability after long-term testing. More importantly, the deciphering of the possible origination of the high activity is performed through the characterization of the intermediates during the OER process, where the electrochemically transformed metal hydroxides and oxyhydroxides are confirmed as the active species.

Self-Sacrificial Template-Directed Vapor-Phase Growth of MOF Assemblies and Surface Vulcanization for Efficient Water Splitting

Direct use of metal-organic frameworks (MOFs) with robust pore structures, large surface areas, and high density of coordinatively unsaturated metal sites as electrochemical active materials is highly desirable (rather than using as templates and/or precursors for high-temperature calcination), but this is practically hindered by the poor conductivity and low accessibility of active sites in the bulk form. Herein, a universal vapor-phase method is reported to grow well-aligned MOFs on conductive carbon cloth (CC) by using metal hydroxyl fluorides with diverse morphologies as self-sacrificial templates. Specifically, by further partially on-site generating active Co₃ S₄ species from Co ions in the echinops-like Co-based MOF (EC-MOF) through a controlled vulcanization approach, the resulting Co₃ S₄ /EC-MOF hybrid exhibits much enhanced electrocatalytic performance toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with overpotentials of 84 and 226 mV required to reach a current density of 10 mA cm^-2 , respectively. Density functional theory (DFT) calculations and experimental results reveal that the electron transfer between Co₃ S₄ species and EC-MOF can decrease the electron density of the Co d-orbital, resulting in more electrocatalytically optimized adsorption properties for Co. This study will open up a new avenue for designing highly ordered MOF-based surface active materials for various electrochemical energy applications.

Metal-containing Ionic Liquid/Polyacrylonitrile-derived Carbon Nanofibers for Oxygen Reduction Reaction and Flexible Zn-Air Battery

Practical applications of Zn-air batteries are usually limited by sluggish kinetics of oxygen reduction reaction. Replacing Pt-based catalysts with convenient, efficient and low-cost materials to boost oxygen reduction reaction is highly desirable. Herein, a class of Fe-N co-doped carbon nanofibers is successfully synthesized by pyrolysis of polyacrylonitrile/metal-containing ionic liquid-based electrospun films. The ionic liquids act as porogen to provide multiscale pores as well as activator to bring carbon nanofibers active sites. The catalyst possessing appropriate active sites and unique 3D porous architecture exhibits remarkable long-term stability and electrocatalytic activity. Particularly, the catalyst maintains a shape of membrane after carbonization, manifesting its direct use as air electrode without binders. It is notable that an all solid-state Zn-air battery based on the carbon nanofibers exhibits good flexibility, indicating its promising application as wearable devices.

A general strategy via chemically covalent combination for constructing heterostructured catalysts with enhanced photocatalytic hydrogen evolution

A general strategy via chemically covalent combination was reported to fabricate heterostructured catalysts of carbon nitride/covalent organic frameworks (CNFs), which show superior photocatalytic activity and higher stability as compared to the conventional heterostructures of CN and COFs connected via van der Waals forces.

Homogeneous guiding deposition of sodium through main group II metals toward dendrite-free sodium anodes

Metallic sodium is a potential anode material for rechargeable sodium-based batteries because of its high specific capacity and low cost. However, sodium commonly suffers from severe sodium dendrites and infinitely huge volume change, hampering its practical applications. Here, we demonstrate that sodium can be controllably deposited through main group II metals such as Be, Mg, and Ba since they have definite solubility in sodium and thus enable a marked reduction of the nucleation barriers of sodium, guiding the parallel growth of sodium on the metal substrates. By further homogeneously dispersing Mg clusters in a three-dimensional hierarchical structure on the basis of a carbonized Mg-based metal-organic framework-74 membrane, the nucleation barriers of sodium can be eliminated, owing to the plentiful Mg nucleation seeds. Hence, a dendrite-free sodium metal anode with a very low overpotential of 27 mV and a superior cycling stability of up to 1350 hours is achieved.

Self-Supporting Hybrid Fiber Mats of Cu3P-Co2P/N-C Endowed with Enhanced Lithium/Sodium Ions Storage Performances

Recently, Cu₃P has been targeted as an alternative anode material for alkali-metal-ion batteries because of their safety potential and high volumetric capacity. However, designing a high-rate Cu₃P electrode with long durability is still faced with huge challenges. Here, we report a self-supporting three-dimensional (3D) composite of Cu₃P and Co₂P interconnected by N-doped C fibers (Cu₃P-Co₂P/N-C). The advanced 3D structure not only provides fast reaction kinetics but also improves the structural stability, leading to excellent rate capability and long-term cycling stability, and pseudocapacitance behavior is also beneficial to the high rate performance. Additionally, the synergistic effects between Cu₃P, Co₂P, and N-doped carbon can increase the electrical conductivity and active sites, ensuring more ion storage. The Cu₃P-Co₂P/N-C anode for lithium-ion batteries delivers high discharge capacity, superior rate performance, and ultralong lifespan over 2000 cycles accompanied by a stable capacity of around 316.9 mAh/g at 5 A/g. When the 3D structured material works in sodium-ion batteries, it also displays improved electrochemical performance. Our method provides a new insight to design advanced metal phosphides anodes for energy storage devices.

WO3 in suit embed into MIL-101 for enhancement charge carrier separation of photocatalyst

Compositing nanoparticles photo-catalyst with enormous surface areas metal–organic framework (MOF) will greatly improve photocatalytic performances. Herein, WO₃ nanoparticles are partly embedded into pores of MIL-101 or only supported on the outside of representative MIL-101, which were defined as embedded structure WO₃@MIL-101@WO₃ and coating structure WO₃&MIL-101 respectively. Different pH, concentration and loading percentage were researched. XRD, TEM and BET were carried to analyze the composites. Compared with the pristine WO₃, all WO₃ loaded MOF nanocomposites exhibited remarkable enhancing for the efficiency of photocatalytic degradation methylene blue under visible light. Their activity of the same loading percentage WO₃ in embedded structure and coating structure have increased for 9 and 3 times respectively compared with pure WO₃. The WO₃@MIL-101@WO₃ has 3 times higher efficiency than WO₃&MIL-101, because the shorter electron-transport distance can make a contribution to electron–hole separation. The further mechanism involved has been investigated by radical quantify experiment, XPS and photoluminescence spectroscopy.

Flexible vanadium-doped Ni2P nanosheet arrays grown on carbon cloth for an efficient hydrogen evolution reaction

Tuning the electronic structure, morphology, and structure of electrocatalysts is of great significance to achieve a highly active and stable hydrogen evolution reaction (HER). Herein, combining hydrothermal and low temperature phosphidation methods, V-doped Ni2P nanosheet arrays grown on carbon cloth (V-Ni2P NSAs/CC) were successfully prepared for the HER. It is found that the prepared V-Ni2P NSAs/CC exhibits preeminent performance for the HER. Specifically, it only requires an overpotential of 85 mV to achieve a current density of 10 mA cm-2 in 1.0 M KOH solution. Moreover, the V-Ni2P NSAs/CC shows superior electrochemical stability, maintaining its HER performance up to 3000 cyclic voltammetry cycles. This work affords a guiding strategy for the synthesis of a high-performance and stable electrocatalyst for the HER.

Applications of Metal-Organic-Framework-Derived Carbon Materials

Carbon materials derived from metal-organic frameworks (MOFs) have attracted much attention in the field of scientific research in recent years because of their advantages of excellent electron conductivity, high porosity, and diverse applications. Tremendous efforts are devoted to improving their chemical and physical properties, including optimizing the morphology and structure of the carbon materials, compositing them with other materials, and so on. Here, many kinds of carbon materials derived from metal-organic frameworks are introduced with a particular focus on their promising applications in batteries (lithium-ion batteries, lithium-sulfur batteries, and sodium-ion batteries), supercapacitors (metal oxide/carbon and metal sulfide/carbon), electrocatalytic reactions (oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction), water treatment (MOF-derived carbon and other techniques), and other possible fields. To close, some existing problem and corresponding possible solutions are proposed based on academic knowledge from the reported literature, along with a great deal of experimental experience.