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Hydrogen energy has long been recognized as a clean alternative to conventional fossil fuels, which can be applied in a wide range of transportation and power generation applications. The rational design and engineering of high-performance and robust catalysts for hydrogen evolution reaction (HER) shows not a great significance but a challenge for efficient electrochemical water splitting. Herein, a new type of Ni-based Ni-ABDC precursor has been obtained, which leads to the formation of N-doped porous carbon nanomaterials uniformly coated with well-proportioned bimetallic AgNi alloys via a stepwise strategy. To their credit, all samples of AgNi/NC-X are structurally calcined from the pristine AgNi-ABDC-X by tuning the different concentration of AgNO3, which means all of them maintain the vermicelli-like morphology compared with Ni-ABDC. The series of AgNi/NC-X materials can be regarded as effective electrocatalysts for HER both in acidic and alkaline media, but an acid-leaching phenomenon is observed. Among them, the as-prepared AgNi/NC-2 exhibits a low overpotential of 103 mV at the current density of 10 mA cm−2 and decent durability with a high retention rate of 90.9% after 10 h in 1.0 M KOH electrolyte. The compelling HER properties of AgNi/NC-2 can be attributed to the synergistic effect between the hierarchical carbon materials, partial N-doping and abundant AgNi alloys. Meanwhile, this study provides a practicable method for the development of efficient HER electrocatalysts for energy applications, which can be conveniently prepared through the reasonable introduction of active components in the crystalline inorganic-organic precursors.

Various electrode materials and relevant modification approaches used for zinc-halogen, hydrogen-halogen, and polysulfide-halogen ARFB systems are summarized, and the relevant mechanisms and regulatory means are illustrated.

Oxygen evolution reaction (OER) on the anode has become one of the most widely studied electrochemical processes, which poses an important role in several energy generation technologies. In this work, we have designed and synthesized a series of metal-organic framework (MOF)-derived oxides pyrolyzed at different temperatures for efficient water oxidation in alkaline solutions. First, the barrel-shaped BMM-10 microcrystals can be conveniently synthesized under solvothermal conditions, and the hollow morphology of BMM-10-Fe with low crystallinity can be obtained through the fierce hydrolysis of Fe(III) ions. After being oxidized in air, there are only two typical phases of oxides including BMM-10-Fe-L and BMM-10-Fe-H. During electrolysis, BMM-10-Fe-L turns out to be immediately degraded into active Ni/FeOOH nanosheets with improved OER performance, while there is almost no structural and morphological change in BMM-10-Fe-H due to the structural rigidity and robust stability. Furthermore, the optimal BMM-10-Fe-H exhibits a promising electrocatalytic OER performance with a low Tafel slope of 137.4 mV dec-1, a small overpotential of 260 mV at 10 mA cm-2, and a high current retention of 93.8% after the stability test. The present work would motivate the scientific community to construct various MOF-derived nanomaterials for efficient energy storage and conversion applications.

One type of porous carbon nanomaterial decorated by abundant Pt/ZrO

With the development of renewable energy systems, clean hydrogen is burgeoning as an optimal alternative to fossil fuels, in which its application is promising to retarding the global energy and environmental crisis. The hydrogen evolution reaction (HER), capable of producing high-purity hydrogen rapidly in electrocatalytic water splitting, has received much attention. Abundant research about HER has been done, focusing on advanced electrocatalyst design with high efficiency and robust stability. As potential HER catalysts, metal nanoclusters (MNCs) have been studied extensively. They are composed of several to a hundred metal atoms, with sizes being comparable to the Fermi wavelength of electrons, that is,2.0 nm. Different from metal atoms/nanoparticles, they exhibit unique catalytic properties due to their quantum size effect and low-coordination environment. In this review, the activity-enhancing approaches of MNCs applied in HER electrocatalysis are mainly summarized. Furthermore, recent progress in MNCs classified with different stabilization strategies, that is, the freestanding MNCs, MNCs with organic, metal and carbon supports, are introduced. Finally, the current challenges and deficiencies of these MNCs for HER are prospected.

The rational design and facile synthesis of transition metal-based catalysts supported by carbon nanomaterials with high activity, selectivity and stability remain a great challenge. Recently, the low-cost, stable and high-performance electrocatalysts for efficient oxygen evolution reaction (OER) derived from porous metal-organic framework (MOF) precursors have attracted numerous attention. Herein, a new type of CoMo carbide/nitride embedded in the flower-like carbon materials (CoMo-MI-T, MI = 2-Methylimidazole, T = 400, 500, 600, 700 °C) has been synthesized by a simple pyrolysis, in which bimetallic CoMo-MI precursors can be conveniently converted from crystalline cobalt-based MOFs of Co-MI by solvothermal reaction. The pyrolyzed CoMo-MI-T series exhibits a hierarchically porous nanostructure, high Co3Mo3C/N content, suitable N-doping, graphitic carbon layers as well as well-preserved flower-shaped morphology, which shows an excellent OER performance. Among them, the most optimal CoMo-MI-600 owns the small overpotential of 316 mV at 10 mA cm−2 and Tafel slope of 89.9 mV dec−1 in 1.0 M KOH solution. Meanwhile, the rotating ring-disk electrode technique is examined to verify near 4-electron transfer process for CoMo-MI-600 together with a high Faradaic efficiency of 98.7%. The well-performed CoMo-MI-600 electrocatalyst may be stemmed from the best balance of the synergistic effect of abundant multi-component, suitable electrical conductivity and large porosity. The current work will provide a new route to prepare MOF-derived bimetallic active sites in porous carbon nanomaterials with satisfactory activity and robust stability in the relevant energy applications.

Herein, we present a stepwise approach for constructing 3-dimensional porous carbon foam pretreated via glutaraldehyde cross-linking and decorated with highly dispersed molybdenum carbide (CF-Glu-Mo) or Co-doped FeNi carbonate hydroxide (CF-Glu-CoFeNi), which is structurally derived from the initial chitosan hydrogel. The as-prepared CF-Glu-Mo and CF-Glu-CoFeNi can act as mono-functional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. In 1.0 M KOH, CF-Glu-Mo exhibits a small overpotential of 88 mV with a low Tafel slope of 56 mV dec−1 under the working condition of 10 mA cm−2 for HER, and CF-Glu-CoFeNi requires an overpotential of 290 mV for OER to reach a current density of 50 mA cm−2, accompanied by a low Tafel slope of 115 mV dec−1. In this case, these integrated electrodes derived from the robust interconnection between the electrocatalyst and the chitosan hydrogel derived carbon foam make the whole water decomposition behavior more direct and efficient, which is reasonably attributed to hierarchically porous nanostructures and intrinsically high conductivity. The full electrolyzer assembled with carbon cloth (CC) of CF-Glu-Mo/CC||CF-Glu-CoFeNi/CC can drive full alkaline water splitting by applying a voltage of 1.65 V at a catalytic current of 10 mA cm−2 for 24 h. Meanwhile, this work provides a feasible approach for the development of efficient water splitting electrocatalysts through the rational design and regulation of heterogeneous interfaces and nanostructures.

Low-cost heteroatom-doped carbon nanomaterials have been widely studied for efficient oxygen reduction reaction and energy storage and conversion in metal-air batteries. A Masson pine twigs-like 3-dimensional network construction of carbon nanofibers (CNFs) with abundant straight long Co, N, and S-doped carbon nanotubes (CNTs) is developed by thermal treatment of Co-based polymer coated onto polyacrylonitrile nanofiber network together with thiourea at 900 °C, denoted as CNFT-Co9 S8 -900. It is interesting to note that the introduction of a high concentration of sulfur does not lead to the complete toxicity of catalysts, but promotes the axial growth to selectively form straight CNTs instead of curly bamboo-like CNTs. The highly graphitized in-situ grown Co, N, S-doped CNTs and the 3-dimensional N-doped CNF network provide both active catalytic sites and highly conductive paths, which are beneficial for oxygen reduction reaction (ORR). Thus, the optimal CNFT-Co9 S8 -900 performs the excellent ORR catalytic activity with a half-wave potential of 0.84 V and a diffusion-limited current density of 5.49 mA cm-2 . Furthermore, the CNFT-Co9 S8 -900-based Zn-air devices also possess a high power density of 136.9 mW cm-2 better than commercial Pt/C.

The exploration and development of cost-effective and highly stable electrocatalysts with the highest possible energy efficiency remain a constant pursuit in the catalyst design and synthesis for electrocatalytic hydrogen evolution reaction (HER). In this work, a convenient approach is proposed to synthesize a type of ultrafine Mo2C nanoparticles in average sizes of 3–4 nm embedded in hierarchically porous N-doped carbon material calcined from bimetallic ZnMo-MI (MI = 2-methylimidazole) is obtained at 1000 °C, denoted as ZnMo-MI-1000. First of all, the crystalline hybrid metal-organic framework of ZnMo-MI is fabricated from zeolitic imidazolate framework of Zn-MI precursors via solvothermal reaction, in which the conversion from Zn-MI to ZnMo-MI occurs gradually over time. After calcination, the as-obtained ZnMo-MI-1000 sample shows a satisfying HER performance with the small overpotential of 83.0 mV in 0.5 M H2SO4 and 100.1 mV in 1.0 M KOH to reach a current density of 10 mA cm−2, which is attributed to ultrasmall Mo2C, Mo and N-doped graphitic carbon matrix. The multiporous network of ZnMo-MI-1000 can provide continuous mass transportation with a minimal diffusion resistance that produce effective electrocatalytic kinetics in both acidic and alkaline media, which is utilized as a highly active and durable nonprecious metal electrocatalyst for HER.

The rapid development of suitable and cheap water oxidation catalysts is of great significance in energy conversion and storage. In this context, herein we have synthesized two different types of metal-organic frameworks (MOFs, denoted as

For electrocatalysis, the development of highly active and low-cost stable electrocatalysts, which would be directly applied in cathodes for fuel cells that are regarded as the most promising candidates for clean energy conversion in the quest for alternatives to conventional fossil fuel technology, remains a massive challenge. In this context, oxygen reduction reaction (ORR) is a critical process under intense research for the direct conversion of chemical energy into electricity. Herein, a facile synthetic method is proposed for the preparation of hierarchically porous 2-dimensional nanosheets consisting of Fe4C and FeCo nanoparticles incorporated in N/S-doped carbon materials at 900 °C, denoted as InFeCo@CNS900. This composite can be conveniently prepared by directly calcining the crystalline indium-organic framework of InOF-24, which is impregnated with the ferric thiocyanate and cobalt ammonium complexes under Ar atmosphere, in which Fe4C and FeCo nanoparticles were in situ formed and embedded into the well-developed carbon materials, which display the hierarchically porous nanosheets with microporous and mesoporous structures. Due to the synergistic effects between different active substances, high specific surface area, suitable graphitization degree, and rich active sites, the as-obtained InFeCo@CNS900 electrocatalyst exhibits an excellent ORR activity, which shows a lower Tafel slope of 59.5 mV dec-1, higher diffusion limit current of 5.15 mA cm-2, and better stability than the commercial 20 wt% Pt/C catalyst. This study provides a facile approach for the design and synthesis of highly efficient non-noble metal-doped carbon materials with a unique 2-dimensional morphology, which are potentially applied in energy science and technology.

Due to the harmfulness of diabetes, a fast and efficient glucose detector is particularly important. Metal-organic polyhedron (MOP) provides a porous framework and a special matrix, which makes it an excellent precursor for electrochemical detection. Herein, we report a novel MOP as a precursor for the preparation of an electrocatalytic detector for glucose. The new metal-organic polyhedron of Cu

Environmentally friendly and efficient transition metal phosphide (TMP) electrocatalysts for oxygen evolution reaction (OER) are developed to meet the growing demand for clean energy. Here we report a novel and environmentally friendly strategy for the preparation of MOF-derived bimetallic phosphide embedded in the carbonaceous matrix (FeNiP/C). With 3-dimensional hollow barrel shape and high specific surface, FeNiP/C-900 performs excellent OER catalytic performance, reaching a current density of 10 mA cm−2 at an overpotential of 229 mV with a low Tafel slope of 74.5 mV dec−1. Meantime, we explore the thermal conversion mechanism of P-containing MOF and the compositional changes during heat treatment.

A stepwise method is used to synthesize partially nitrided electrocatalyst from Cu-based metal–organic polyhedron for the first time. The obtained MOP-CAN shows trace Cu3N as well as metallic Cu nanoparticles anchoring on the graphitic carbon layer, which exhibits a satisfying oxygen evolution performance competitive to the precious metal-based catalysts.

Crystalline metal-organic frameworks (MOFs) are an emerging type of the hybrid materials with multifunctional inorganic and organic building blocks, which have been applied in a wide range of energy-related and environment-related applications. In this context, a remaining challenge in the systematical syntheses of hierarchically porous MOFs composites is existing to alter supermolecular structure, chemical composition, and versatile functionality. It is generally accepted that the regulation of MOF preparation is of great significance, which is related to the solubility of those starting inorganic components. We learn that there are several possible drawbacks induced by conventional soluble metal precursors in homogeneous reaction conditions, so the increasing research interest in the facile synthesis of MOFs and their derivatives from insoluble metal templates and/or precursors has been ignited in the past decade. In this review, we aim to provide an overview of the facile preparation and usage of MOF materials by using the unconventional inorganic precursors in heterogeneous synthetic conditions, including template types, preparation methods, extension strategies, advantages, limitations and related applications.

It is of great importance to find non-precious metal based oxygen reduction reaction (ORR) catalysts with high stability, high performance and low cost. In this context, hierarchically porous carbon-based nanomaterials doped with heteroatoms are regarded as one of promising catalysts for ORR. Herein, a bottom-up approach is proposed by using the initial MOF-derived CoO@ZIF-67 core-shell structure as a template to obtain hollow cobalt-anchored N-doped carbon material followed by acid etching (A-CoNC). It exhibits a type of hollow porous nitrogen-carbon network anchored by well-dispersed atomic Co-Nx sites with high activity and stable catalytic performance. The as-obtained A-CoNC shows high electrocatalytic ORR activity, good reaction selectivity with the low Tafel slope of 55.5 mV dec−1, large limited current density of 5.37 mA cm−2 and excellent long-term stability (retention = 96.1%, time = 10 h). Furthermore, A-CoNC can also be serving as efficient electrocatalysts for zinc-air battery with a high power density of 144.0 mW cm−2. Our synthetic strategy from the MOF-derived core-shell structure to ORR electrocatalyst provides new pathway for the design and preparation of highly efficient electro-/photo-catalysts stemmed from MOFs materials.

In the preparation of nanomaterials, the kinetics and thermodynamics in the reaction can significantly affect the structures and phases of nanocrystals. Therefore, people are keen to adopt various synthetic strategies to accurately assemble the target nanocrystals, and reveal the underlying mechanism of the formation of specific structures. In this work, the total reaction time is adjusted to let the prepared MnCo Prussian blue analogous (MnCoPBA) crystals show four evolving morphological changes at different stages with the assistance of sodium dodecyl sulfate. Furthermore, it is clearly observed that the epitaxial growth along the (100) plane on the shell of MnCoPBA nanocrystals is favored, and the thermodynamics and kinetics in the morphology change process are analyzed in detail. Through the simple pyrolysis, MnCoPBA crystals can be successfully converted into the corresponding carbon composites, of which Mn2 Co2 C nanoparticles are evenly distributed in highly graphitized carbon matrix. Among them, PBA-III-700 performs good oxygen reduction reaction performance in alkaline solution with the half-wave potential of 0.801 V and diffusion-limited current density of 5.36 mA cm-2 , and its zinc-air battery exhibits the peak power density of 103.4 mW cm-2 competitive with commercial Pt/C.

Rapid deployment of renewable energy causes a significant change in environmental benefits. Thus, the transition metal-based electrocatalysts are developed to achieve efficient water splitting. Here a simple three-step method is adopted to successfully synthesize a type of hollow MOF-derived three-dimensional carbonaceous matrix that is randomly loaded with numerous FeNi3 alloy nanoparticles (NiFeC). In this work, the as-obtained NiFeC-800–5(carbonization temperature: 800 °C; pyrolysis rate: 5 °C/min) shows an excellent oxygen evolution reaction catalytic activity in 1.0 M KOH electrolyte, with a low overpotential of 269 mV at 10 mA cm-2 and a low Tafel slope of 72 mV dec‑1. Moreover, it exhibits an ultrastable durability after being electrolyzed continuously for 10 h, which is originated from these fine alloys encapsulated into the hierarchically porous carbonaceous material. Finally, we have proposed morphological and chemical changes for the NiFeC-800–5sample, in which the solid MOF precursor will be gradually etched into the hollow morphology by the strong hydrolysis of Fe(III) ions at high temperature, and the optimal carbonization temperature and heating rate are also well investigated. Moreover, the above approach can be used to obtain other MOF derived bimetallic alloy nanoparticles encapsulated into carbon materials for the energy conversion and storage applications.

Exploiting non-noble metal bifunctional electrocatalysts for efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a feasible approach for developing clean energy. Herein, we synthesize a transition metal coordinating nitrogen (Fe/Ni-N) doped carbon material (FeNi-MNC) with unique morphology combining external diverging carbon nanotubes and internal carbon matrix with ordered macropore alignments. With the co-catalysis of Fe and Ni species and the space limiting of SiO2 template in carbonation, the obtained FeNi-MNC shows high Fe/Ni-N contents. Profiting from the hierarchical morphology and abundant active sites, the catalyst exhibits excellent activity for ORR in 0.1 M KOH with a half-wave potential of 0.834 V and a Tafel slope of 53.1 mv dec−1 being superior to Pt/C. Moreover, it only needs an overpotential of 298 mV reaching 10 mA cm−2 for OER in 1.0 M KOH. Our work constructs a 3-dimensional porous carbon matrix integrated with 1-dimensional carbon nanotubes and 2-dimensional carbon nanosheets to enhance the catalytic performance.

One new type of electrochemical sensors for the effective glucose detection is fabricated based on the use of CuOx@Co3O4 core-shell nanowires on Cu foam as electrocatalysts, which is synthesized through the stepwise process, including anodized nano-sized Cu(OH)2 wires, Metal-organic frameworks (MOFs)-wrapped Cu(OH)2 nanowires, and the following calcination. These as-made hierarchical composites exhibit the structural characteristics of CuOx nanowires core and Co3O4 nanoparticles shell calcinated from the terminally attached microporous ZIF-67. This type of glucose sensor compared to pure individual metal oxides exhibits higher sensitivity (27778 μA mM−1 cm-2 in the range from 0.1–1300.0 μM), lower detection limit (36 nM (S/N = 3)) and faster response time (∼1 s), also displays satisfactory selectivity, reproducibility, and long-term storage stability. Meanwhile, it achieves well-pleasing results in the detection of glucose in real human blood serum compared to commercial sensors. In addition, other four types of self-supporting MOF-derived bimetallic oxides core-shell nanowire arrays on Cu foam are also prepared by adopting the similar three-step procedure, including CuOx@Fe2O3, CuOx@NiO, CuOx@CuOx and CuOx@ZnO core-shell nanowires, demonstrating the versatility of this method. These results confirm that our as-made MOF-derived bimetallic oxide based sensor of CuOx@Co3O4 has a great potential application in the development of enzyme-free sensors for monitoring glucose.

2-dimensional Co nanoparticles embedded in N-doped carbon nanosheets (NCNS) are derived from indium-based frameworks which are impregnated with discrete [Co(NH3)6]3+ ions by high-temperature pyrolysis as a new approach to convert a 3-dimensional porous metal-organic frameworks (CPM-5) to 2-dimensional functional nanosheets. The as-made porous Co, N-doped carbon nanosheets (NCNS–Co0.5In0.5) perform the excellent ORR catalytic activity with a half wave potential of 0.82 V in comparison with the commercial Pt/C. Meanwhile, it also owns good stability and methanol tolerance as a suitable catalyst for zinc-air batteries with a high power density of 132.2 mW cm−2. This method can easily be extended to other In-based MOFs, including QMOF-2, In-MIL-68, InOF-1, in which all the corresponding derived materials exhibit efficient ORR performance. Especially, the porous Co, N-doped carbon nanosheets annealed from InOF-1 (InOF-1-Co-800) display an Eonset of 0.93 V, a half-wave potential of 0.85V, and a diffusion-limited current of 5.40 mA cm−2 density. Our work provides a new path to tune the morphology and catalytic performance of MOF derivatives.