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Exploiting high-performance, low-cost, and robust bifunctional catalysts toward electrochemical water splitting is of great importance, but remains challenging.

Surface reconstruction engineering is proposed to construct silver nanoparticle-loaded nickel–cobalt (oxy)hydroxides, which shows significantly enhanced catalytic OER and UOR performance along with long-term stability.

Searching for efficient and cost-effective electrocatalysts for hydrogen evolution reaction (HER) is significantly desirable and challenging. Herein, N, P co-doped carbon-encapsulated CoP/MoP hybrid (CoP/MoP@NPC) is fabricated using dual-metal-organic-framework (dual-MOF) as precursor by a simple one-step phosphating process. When applied as an electrocatalyst toward the HER, the as-designed CoP/MoP@NPC hybrid shows efficiently catalytic performance with a lower overpotential of 183 mV to deliver a current density of 10 mA cm

Rational design of efficient, low-cost, and durable electrocatalysts for the hydrogen evolution reaction (HER) in various pH media is highly desirable but remains challenging. Herein, for the first time, we present a novel hybrid of ruthenium diphosphide encapsulated in P-doped porous carbon (denoted as RuP2@PC) utilizing metal–organic frameworks (MOFs) as templates by a multi-step strategy. Unexpectedly, benefitting from the synergistic contribution of highly dispersed ultrafine RuP2 nanoparticles, porous carbon skeleton, and P-dopant, the as-synthesized RuP2@PC exhibits exceptional catalytic activity and superior durability as pH-universal electrocatalysts for the HER. Particularly, a low overpotential of 78.9 mV to deliver a current density of 10 mA cm−2 and a small Tafel slope of 36.7 mV dec−1 can be achieved in 1.0 M KOH toward the HER. Such outstanding electrocatalytic properties exceed those of commercial Pt/C and rank the catalyst among the best HER electrocatalysts reported until now. Importantly, this work paves a new route in elaborately fabricating efficient and stable electrocatalysts based on MOFs for energy-related fields.

N,P-codoped porous carbon hollow nanosphere confining ultrafine molybdenum carbide nanoparticles are designed and prepared through a facile method. By virtue of the distinct composite and structure advantages, the resulting composite shows significantly enhanced electrocatalytic performance toward the hydrogen evolution reaction.

Rational design and development of ruthenium phosphide-based nanomaterials with Pt-like catalytic performance and long-term stability for hydrogen evolution reaction (HER) are highly desirable. Herein, a three-dimensional (3D) hybrid of graphene hollow nanospheres-supported ruthenium phosphides through a nanosphere-directed templating approach is developed. As expected, when evaluated as an electrocatalyst for the HER, the resultant composite exhibits excellent catalytic performance over a wide pH range due to the synergistic effects of the unique structure and composition. Particularly, the catalyst shows a low overpotential of 25.5 mV to achieve the current density of 10 mA cm−2, a small Tafel slope of 34.4 mV dec−1, as well as long-term operational stability for 10 h in basic conditions, which is superior to all other reported HER catalysts, including commercial 20% Pt–C. More importantly, this work provides new options for the design of 3D hollow graphene nanospheres supported transition metal phosphides as high-performance electrocatalysts for large-scale hydrogen production.

Ruthenium-doped amorphous molybdenum dioxide coupled with reduced graphene oxide hybrid (Ru-MoO2@PC/rGO) is synthesized using POMOF/GO as precursor. Benefitting from the synergistic effect of numerous exposed active sites, Ru dopants, and introduction of GO, the designed catalyst shows exceptional electrocatalytic performance toward the HER in alkaline media.

Rational design and construction of non-noble electrocatalysts with high efficiency and good stability is one of the hottest fields for the oxygen reduction reaction (ORR). Herein, for the first time, we describe a novel nanocomposite composed of isolated single-atomic Co sites anchored on 3D hollow graphene nanosphere (Co ISAs/GHS) substrates through a reliable SiO2-assisted strategy. As expected, the as-formed Co ISAs/GHSs exhibit a prominent ORR electroactivity in 0.1 M KOH solution, delivering a more positive half-wave potential of 0.82 V, higher selectivity (four-electron-transfer), and superior methanol tolerance along with long-term stability, originating from the unique components and well-designed structural advantages. Remarkably, the presented work provides a myriad of opportunities to develop highly dispersed single-atomic-site catalysts with highly efficient activity for diverse electrocatalysis applications.

Ultrafine Ru nanoparticles dispersed on 3D N-doped carbon hollow nanospheres were firstly prepared by a feasible templating strategy. Due to the synergistic effect of the unique composite and structure, the resulting nanocomposite as a HER catalyst shows extraordinary electrocatalytic performance, superior to that of commercial Pt-C and most previously reported electrocatalysts.

The development of highly active and robust Pt-free catalysts is of great significance for electrocatalytic hydrogen production. Herein, we illustrate the design of Ru-doped cobalt phosphide nanoca...

Electrochemical water splitting is widely recognized as an effective strategy for economical both hydrogen and oxygen production. Herein, a facile carbonization-oxidation-phosphidation strategy is proposed to construct a novel nanocomposite consisting of CoxP (a mixture of Co2P and CoP) nanoparticles encapsulated in N-doped carbon porous polyhedrons based on surface functionalized ZIF-67, which serves as a high-performance electrode material for overall water splitting. With the merits of highly active CoxP nanoparticles and distinct structure characteristics, the resultant composite exhibits superior catalytic behaviors toward both the hydrogen evolution reaction and oxygen evolution reaction in alkaline electrolytes. When the as-prepared hybrid is adopted as both the cathodic and anodic catalysts in an alkaline medium, the electrolyzer can deliver a current density of 10 mA cm−2 at a low cell voltage of ∼1.71 V. More importantly, this work sufficiently proves that surface engineering route is feasible to develop high-efficiency bifunctional electrocatalysts toward overall water splitting application.

N,P-codoped porous carbon hollow nanosphere confining ultrafine molybdenum carbide nanoparticles are designed and prepared through a facile method. By virtue of the distinct composite and structure advantages, the resulting composite shows significantly enhanced electrocatalytic performance toward the hydrogen evolution reaction.

Rational design and exploitation of efficient and inexpensive catalysts for water electrolysis are highly desired, yet very challenging. Herein, for the first time, we report a nanostructured catalyst of nickel phosphides-ruthenium phosphides self-supported on nickel foam (Ni2P-Ru2P/NF) through an in situ growth-phosphorization process. As expected, by virtue of prominent intrinsic activity, rich electrochemically active sites, and high electronic conductivity, the resultant Ni2P-Ru2P/NF exhibits enhanced electrocatalytic behavior for the oxygen evolution reaction and hydrogen evolution reaction, which delivers low overpotentials of 160 and 101 mV at 10 mA cm 2 in alkaline media, respectively. Remarkably, the Ni2P-Ru2P/NF can dramatically accelerate full water splitting with an ultralow cell voltage of 1.45 V at 10 mA cm-2, which far exceeds the benchmark Pt-C/NF//RuO2/NF (1.64 V) and ranks among the best electrocatalysts previously reported.

Rational design and synthesis of low-cost electrocatalysts with high-performance is of urgency for hydrogen evolution reaction (HER). Herein, we report a facile synthetic approach to construct a pomegranate-like MoP@P-doped porous carbon nanospheres coupled with carbon nanotubes (CNTs) composite using metal-organic frameworks-CNTs hybrid as precursor, which was successfully employed as a robust electrocatalyst for the HER. Ascribed to the distinct nanostructure together with the synergistic coupling, the resultant composite exhibits highly efficient electrocatalytic performance, featured by a low onset overpotential of 75 mV, small Tafel slope of 55.9 mV dec−1, as well as long-term stability for 10 h, which is comparable or even superior to the best MoP-based catalysts toward HER up to now. More importantly, this strategy can provide a new route in the construction of highly efficient Pt-free electrocatalysts for energy conversion fields.

Two Keggin polyoxometalate (POMs) based hybrid compounds containing helix/nanocages as peroxidase-like mimics have been synthesized and structurally characterized. Single crystal X-ray diffraction analysis reveals that compound 1 exhibits a POM-pillared framework with open nanotube channels (ca. 5.6 × 5.8 A2), in which SiW12 polyanions are sandwiched between the adjacent Cu-fkz sheets with meso-helix. And an unprecedented twisted octahedral hexamer nanocage (ca. 10 × 10 A2) is observed in compound 2. Compared with the other POMs involved peroxidase-like mimics, both compounds 1 and 2 exhibit higher peroxidase-like catalytic activities, broader applications range, faster respond time and lower detection limit, which maybe attribute to the maximized synergistic effects of SiW12 clusters, fkz molecules, metal ions and the distinct structure. Based on the facts, compounds 1 and 2 as enzyme mimics might expand their application around physiological pH conditions, and can be used as one kind of effective probe to detect H2O2 in live organism.

Two new Wells–Dawson polyoxometalate-based metal–organic frameworks (POMOFs) with different helical channels were synthesized depending on the self-adaptive coordination nature of P2W18 polyanion. The hemispherical coordination of P2W18 clusters with Ag under the help of 1,2,4-triazole ligand induces the isolation of the twofold helical channels-containing POMOF 1, while the clockwise coordination of P2W18 clusters with Cu results in the fourfold helical channels-containing POMOF 2. Both compounds exhibit good electrochemical performance as lithium-ion batteries electrode materials due to their excellent redox properties and structural stabilization. The long-term cycling capacity as demonstrated by the still above 400–450 mA h g–1 for 350 cycles at the current density of 100 mA g–1 reveals the important role of the helical channels within exposed P2W18 polyanions in 1 and 2, which allow the relatively easy Li+ deintercalation/intercalation. To illustrate the lithium storage, the impedance spectra of comp...

A new polyoxometalate based hybrid compound containing Ag-Ag chain, [Ag29(trz)18][SiWV7WVI5O40] (Ag29SiW12), was synthesized by the simple one-step hydrothermal reaction of silver nitrate, 1, 2, 3- triazole (trz), and [SiW12O40]4- polyanion. Single crystal X-ray diffraction analysis shows that the [SiW12O40]4- polyanions as coordinating guests were successfully encapsulated into the metal-organic framework host matrix. The Keggin [SiW12O40]n- polyanions as templates and trz molecules as the small and delicate ligands play the decisive factors to the formation of silver chain. In addition, to improve the photocatalytic activity of the new compound Ag29SiW12, its polypyrrole (PPy) composite (PPy@Ag29SiW12) has been prepared and exhibits excellent photocatalytic activity (93.1% for MB and 48.8% for RhB) and selectivity adsorption (16.2 mg/g for MB and 1.60 mg/g for RhB) for organic dyes under the visible light radiation.

Hydrogen as a clean and environmentally friendly energy carrier has attracted extensive interest. Although Pt-based materials have been considered as the state-of-the-art catalysts for the hydrogen evolution reaction (HER), the high-cost and low-abundance hinder their practical application. Herein, we report the development of reduced graphene oxide (rGO) supported molybdenum phosphide (MoP) encapsulated in P-doped porous carbon (PC) nano-octahedrons derived from polyoxometalate-based metal–organic frameworks (POMOFs) by carbonization and subsequent phosphidation process. Impressively, combining the advantages of MoP, PC, and rGO, the composite shows superior electrocatalytic HER performance and stability, with a low onset overpotential of 62.3 mV, small Tafel slope of 53.6 mV dec–1, along with long-term durability for 10 h, which is comparable or even superior to those of the most promising MoP-based electrocatalysts in acid media reported to date. Most importantly, this work provides an elaborate strate...

The design and fabrication of noble-free metal electrocatalysts for efficient hydrogen production with long-term stability are of great significance, but very challenging. Herein, for the first time, we report an iron phosphide/molybdenum phosphide hybrid covered by nitrogen/phosphorus dual-doped carbon (FeP/MoP@NPC) using polyoxometalate-based metal-organic frameworksas templates by a facile two-step approach. As expected, the composite shows highly efficient electrocatalytic performance toward the hydrogen evolution reaction with a low onset overpotential (76 mV), small Tafel slope (56.5 mV dec–1), and excellent catalytic stability for 10 h owing to its distinct nanostructure and strong synergistic effect of FeP and MoP. More importantly, this work offers a novel methodology for exploiting transition-metal-based electrocatalysts for clean and renewable energy technology.

Controlled self-assembly of the inorganic–organic hybrid compounds based on polyoxometalates (POMs) is hampered by the wide range of oxo and hydroxo units on the peripheries of POMs and many chemic...

The development of highly efficient and durable non-noble metal catalysts for full water splitting has attracted tremendous attention in recent years. Herein, for the first time, we present a facile synthesis of FeCo alloys encapsulated in a nitrogen-doped graphite/carbon nanotube (FeCo@NG/NCNT) hybrid using MOFs as precursors. Impressively, due to the synergistic interplay between FeCo alloys and NG/NCNTs, the resultant hybrid as a bi-functional electrocatalyst demonstrates an outstanding electrocatalytic performance for both oxygen and hydrogen evolution reactions in alkaline electrolytes. Most importantly, this work paves a new route in rationally designing and developing high-efficienct and stable bifunctional electrocatalysts for overall water splitting.

A new general route was developed for the synthesis of polyoxometalate (POM)-based [6]catenane frameworks. The hydrothermal reaction of 1,2,4-triazole and AgNO3 with the saturated Keggin polyoxoanions [SiW12O40]4–/[PMo12O40]3–/[AsW12O40]3– as a template led to the successful isolation of POM[n]catenane members [Ag(trz)][Ag12(trz)9][HSiW12O40]·2H2O (1), [Ag(trz)][Ag12(trz)9][PMo12O40]·2H2O (2), and [Ag(trz)][Ag12(trz)9][AsW12O40]·2H2O (3). Single crystal X-ray diffraction analysis not only clearly reveals their [6]catenane nature but also discloses their regular three-dimensional infinite polycatenated structure with a self-dual NaCl-type topology. And for the first time, POM[6]catenane (1 and 2) are used as anode materials in lithium-ion batteries, which exhibit promising electrochemical performance with the first discharge capacities of 1182 mAh g–1 for 1 and 1355 mAh g–1 for 2, and stabilized discharge capacity of 330 mAh g–1 for 1 and 520 mAh g–1 for 2 after 100 cycles at the current density of 0.5 A g–1.

Electrocatalytic water splitting producing hydrogen is of great importance for renewable energy storage and conversion technologies. In recent years, low-cost and high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) have attracted a lot of attention. Herein, we report that in situ-generated Co@nitrogen-doped carbon nanotubes (Co@NCNTs) derived from metal–organic frameworks (MOFs) were fabricated by a facile method and corresponding HER activities were investigated in detail. Among these hybrids, the Co@NCNTs-800 hybrid shows outstanding electrocatalytic activity and stability, which is one of the best Co-based electrocatalysts for the HER under both alkaline and acidic conditions reported to date, benefiting from the synergistic effect from Co nanoparticles, N dopants, and CNTs. Most importantly, this work paves a new way for designing novel, efficient, and inexpensive HER electrocatalysts derived from MOFs as promising alternatives to Pt or Pt-based materials.

Unprecedented polyoxometalate based metal–carbene frameworks (POM-based MCFs) [Cu10(H3trz)4(Htrz)4](HPW12O40) (1) and [Cu10(H3trz)4(Htrz)4](H2SiW12O40) (2) have been fabricated via a hydrothermal reaction between 1,2,4-triazole and Cu(CH3COO)2 with the saturated Keggin polyoxoanion [PW12O40]3−/[SiW12O40]4− as a template for the first time. Single crystal X-ray diffraction analysis reveals the successful encapsulation of Keggin POMs into the three-dimensional POM-based MCFs with lvt-a topology based on their effective coordination with Cu ions. Interestingly, these novel 3D POM-based MCFs exhibit good electrochemical performance in lithium-ion batteries (LIBs) as anode materials, with first discharge capacities of ca. 1620 and 1245 mA h g−1 for 1 and 2, respectively, at a current density of 100 mA g−1, and stabilized discharge capacities of ca. 570 mA h g−1 for 1 and 426 mA h g−1 for 2 after 100 cycles. This, in combination with their high thermal stability, suggests their good LIB application potential.

Highly efficient electrocatalysts for hydrogen evolution reactions (HER) are crucial for electrochemical water splitting, where high-cost and low-abundance Pt-based materials are the benchmark catalysts for HER. Herein, we report the fabrication of MoP nanoparticles confined in P-doped porous carbon (MoP@PC) via a metal–organic framework-assisted route for the first time. Remarkably, due to the synergistic effects of MoP nanocrystals, P dopant, and porous carbon, the resulting MoP@PC composite exhibits superior HER catalytic activity with an onset overpotential of 97 mV, a Tafel slope of 59.3 mV dec–1, and good long-term durability, which compares to those of most reported MoP-based HER catalysts. Most importantly, the work opens a new route in the development of high-performance nonprecious HER electrocatalysts derived from MOFs.

The design and fabrication of electrocatalysts for HER, with superior activity and stability, still remain a significant challenge for clean and renewable energy technologies. Here we have synthesized Fe3C/Mo2C-containing N, P co-doped graphitic carbon derived from POM@MOF-100 (Fe) (denoted as Fe3C/Mo2C@NPGC) via a “killing three birds with one stone” strategy. The Fe3C/Mo2C@NPGC catalyst demonstrates excellent electrocatalytic activity and stability towards HER with a low onset overpotential of 18 mV (vs. RHE), small Tafel slope of 45.2 mV dec−1, as well as long-term durability for 10 h, which is one of the best non-noble metal HER catalysts in acidic media reported so far. Most importantly, this work opens up exciting opportunities for fabricating novel and highly efficient electrocatalysts to replace Pt or Pt-based catalysts utilizing POM-based metal–organic frameworks (MOFs) as precursors.

A polyoxometalate (POM)-assisted fabrication of Pd nanoparticle/reduced graphene oxide (rGO) nanocomposite is reported. The hybrid exhibits enhanced catalytic activity and excellent methanol-tolerance capacity compared to its counterparts, due to the synergistic effect of Pd, POM, and rGO.

For exploring the multifold helical fabrication of polyoxometalate (POM)-based hybrid compounds, four POM-based crystalline compounds with different meso-helices, H3[Ag27(trz)16(H2O)6][SiW12O40]2·5H2O (1), H[Ag27(trz)16(H2O)4][PW12O40]2·2H2O (2), [Ag23(trz)14(H2O)2][HSiW12O40] (3), and [Ag23(trz)14(H2O)2][PW12O40] (4), were successfully isolated by using the delicate 1,2,3-triazole ligand and silver ions in this work. Crystal analysis reveals that compounds 1 and 2 and compounds 3 and 4 are isomorphous and display 2-/4-fold mixed meso-helices and simple 2-fold meso-helices, respectively. In addition, due to the reversible multielectron redox behavior and electron storage functions of POMs, compounds 1 and 3 were studied as anode materials in lithium-ion batteries (LIBs). Compounds 1 and 3 show very high lithiation capacities (1356 and 1140 mAh g–1, respectively) in the initial cycle, which are much higher than those of (NBu4)4[SiW12O40] and commercial graphite at the current density of 100 mA g–1. More im...

A novel nitrogen-doped Fe/Fe3C@graphitic layer/carbon nanotube hybrid derived from MOFs has been first fabricated by a facile approach. The hybrid exhibited outstanding bifunctional electrocatalytic activity for ORR and OER, due to the merits of graphitic layer/carbon nanotube structures with highly active N and Fe/Fe3C sites.

Metal–organic frameworks (MOFs) hybrid composites, combining the advantages of both MOFs and nanoparticles, may exhibit unprecedented properties. Herein, carbon nanodots (Cdots) functional UMCM-1 composites (Cdots@UMCM-1a) were successfully synthesized by a stepwise synthetic approach for the first time. The hybrids retain the intact structure of MOFs with high luminescence and longer stability. Due to the interactions between polar functional groups at the surface of the Cdots and H2 molecules, Cdots@UMCM-1a efficiently enhanced H2 storage capacity. Most importantly, Cdots@UMCM-1a exhibited highly fluorescent sensing for nitroaromatic explosives owing to the double effect of porous MOFs and fluorescent Cdots. This work will pave new avenues for the fabrication of novel and multifunctional MOFs composites.

A coupled hybrid of molybdenum phosphide (MoP) and reduced graphene oxide has been prepared for the first time utilizing Mo-MOFs as precursors through a facile method. The nanocomposite exhibits superior electrocatalytic performance towards the HER, and is one of the best high-performance MoP-based electrocatalysts under acidic conditions reported so far.

A series of remarkable crystalline compounds containing metallapillararene/metallacalixarene metal-organic frameworks (MOFs), [Ag5(pyttz)3·Cl·(H2O)][H3SiMo12O40]·3H2O (1), [Ag5(trz)6][H5SiMo12O40] (2), [Ag5(trz)6][H5GeMo12O40] (3), and [Ag5(trz)6][H4PW12O40] (4) (pyttz = 3-(pyrid-4-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl, trz = 1,2,4-triazole), have been obtained by using a simple one-step hydrothermal reaction of silver nitrate, pyttz for 1 and trz for 2-4, and Keggin type polyoxometalates (POMs). Crystal analysis reveals that Keggin POMs have been successfully incorporated in the windows of the metallapillararene/metallacalixarene MOFs in compounds 1-4. In addition, the Keggin silicomolybdenate-based hybrid compounds 1 and 2 were used as anode materials in lithium ion batteries (LIBs), which exhibited promising electrochemical performance with the first discharge capacities of 1344 mAh g-1 for 1 and 1452 mAh g-1 for 2, and this stabilized at 520 mAh g-1 for 1 and 570 mAh g-1 for 2 after 100 cycles at a current density of 100 mA g-1. The performances are better than that of (NBu4)4[SiMo12O40] matrix and commercial graphite anodes.

We synthesized a novel mesoporous Mn2O3 nanostructure as an electrocatalyst support, then Pd–Mn2O3 with different Pd loading amounts were obtained by a facile solvothermal method. The Pd–Mn2O3 demonstrated a good competitive ORR activity and a high selectivity in alkaline medium, which can be comparable to commercial Pt/C catalysts.

A novel MOF-templated nitrogen and sulphur co-doped porous material has been synthesized as an efficient electrocatalyst for oxygen reduction reactions (ORRs) for the first time. The representative NS(3 : 1)–C-MOF-5 catalyst shows the highest onset potential, and is even comparable to commercial Pt–C catalyst, due to the synergistic effect of N and S co-doping.

The nitrogen (N), phosphorus (P) and sulphur (S) ternary-doped metal-free porous carbon materials have been successfully synthesized using MOFs as templates (denoted as NPS-C-MOF-5) for oxygen reduction reaction (ORR) for the first time. The influences of porous carbons from carbonizing different MOFs and carbonization temperature on ORR have been systematically investigated. Due to the synergistic effect of N, P and S ternary-doping, the NPS-C-MOF-5 catalyst shows a higher onset potential as a metal-free electrocatalyst for ORR among the currently reported metal-free electrocatalysts, very close to the commercial Pt-C catalyst. In particular, the kinetic limiting current density of NPS-C-MOF-5 catalyst at -0.6 V is up to approximate -11.6 mA cm(-2), which is 1.2 times higher than that of the commercial Pt-C catalyst. Furthermore, the outstanding methanol tolerance and excellent long-term stability of NPS-C-MOF-5 are superior to those of the commercial Pt-C catalyst for ORR in alkaline media.

A novel microporous metal–organic framework, IFMC-16, has been successfully constructed by using mixed ligands. IFMC-16 has multipoint interaction sites and exhibits high hydrogen storage capacity not only at ambient pressure, but also at lower pressure in a high pressure region, and displays high adsorptive efficiency in the removal of organosulfur compounds.