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One-dimensional nanotube heterostructures with IrO2-stabilized La2IrO6 is obtained by an electrospinning approach. The La2IrO6/IrO2 catalyst exhibits superior catalytic activity and strong stability for the oxygen evolution reaction. The synergistic cooperation between the two types of Ir as the active sites in La2IrO6/IrO2 is demonstrated by in situ Raman spectrum and DFT calculation. [ABSTRACT FROM AUTHOR]

Herein a facile and versatile hydrothermal method has been developed to construct a polypyrrole-derived carbon nanotube (PCN), MoS2 nanosheets and a carbon shell integrated sandwich-like heterostructure (PCN@MoS2@C). This heterostructure shows excellent performance in the hydrogen evolution reaction (HER) over a wide pH range. The results indicate that the porous carbon shell coated heterostructure provides MoS2 nanosheets with sufficient conductivity, increased number of active sites, and strong structural stability, and thus boosts its HER performance. [ABSTRACT FROM AUTHOR]

Water electrolysis is an emerging energy conversion technology, which is significant for efficient hydrogen (H2) production. Based on the high‐activity transition metal ions and metal alloys of ultrastable bifunctional catalyst, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are the key to achieving the energy conversion method by overall water splitting (OWS). This study reports that the Co‐based coordination polymer (ZIF‐67) anchoring on an indium–organic framework (InOF‐1) composite (InOF‐1@ZIF‐67) is treated followed by carbonization and phosphorization to successfully obtain CoP nanoparticles–embedded carbon nanotubes and nitrogen‐doped carbon materials (CoP‐InNC@CNT). As HER and OER electrocatalysts, it is demonstrated that CoP‐InNC@CNT simultaneously exhibit high HER performance (overpotential of 153 mV in 0.5 m H2SO4 and 159 mV in 1.0 m KOH) and OER performance (overpotential of 270 mV in 1.0 m KOH) activities to reach the current density of 10 mA cm−2. In addition, these CoP‐InNC@CNT rods, as a cathode and an anode, can display an excellent OWS performance with η10 = 1.58 V and better stability, which shows the satisfying electrocatalyst for the OWS compared to control materials. This method ensures the tight and uniform growth of the fast nucleating and stable materials on substrate and can be further applied for practical electrochemical reactions. [ABSTRACT FROM AUTHOR]

Herein, we present the fabrication of a hollow TMP-based carbon material for efficient oxygen evolution reaction, employing a combined approach of MOF-assisted sacrificial template and epitaxial growth methods. [Display omitted] The sluggish kinetics of the electrocatalytic oxygen evolution reaction (OER) pose a significant challenge in the field of overall water splitting. Transition metal phosphides have emerged as promising catalysts for OER by modulating the charge distribution of surrounding atoms. In this study, we employed self-sacrificing templates to fabricate hollow N -doped carbon spheres containing small-sized Co 2 P embedded within carbon nanotubes through high-temperature calcination and phosphorization, referred to as HNCS-CNT-CoP. The obtained HNCS-CNT-CoP electrocatalyst exhibited excellent OER performance in an alkaline electrolyte due to the optimization of OH* adsorption energy and the large specific surface area created by the hollow structure. It demonstrated a low overpotential of 302 mV at a current density of 10 mA cm−2 and a low Tafel slope of 68.5 mV dec−1, attributed to the electron transport facilitated by the in situ formed carbon nanotubes. Furthermore, theoretical calculations revealed a suitable reaction energy (1.17 eV) in the critical formation of Co 2 P-*OOH for HNCS-CNT-CoP, significantly lower than the the rate-determining step of HNCS-CNT-Co (10.08 eV). These findings highlight the significance of hollow structures and Co 2 P-doping in the design of highly active non-noble metal OER electrocatalysts, enabling the reduction of energetic reaction barriers for future applications. [ABSTRACT FROM AUTHOR]

One type of MOF-derived porous N -doped carbon anchoring iron phthalocyanines has been obtained. Owing to abundant Fe-N4 active centers, FePc@NC-1000 exhibits excellent ORR activity, and its assembled zinc-air batteries also show favorable performance and durability. [Display omitted] • One Zn-based pillar-layer MOF nanosheet is easily achieved by its restricted axial growth. • Iron phthalocyanines could be firmly immobilized into MOF-derived porous Ndoped carbons. • The optimal catalyst of FePc@NC-1000 shows high oxygen reduction activity and durability. Functional carbon nanomaterials play a crucial role in the cathodic oxygen reduction reaction (ORR) for sustainable fuel cells and metal-air batteries. In this study, we propose an effective approach to immobilize iron phthalocyanines (FePc) by employing a porous N -doped carbon material, denoted as NC-1000 , derived from a sheet-shaped coordination polymer. The resulting NC-1000 possesses substantial porosity and abundant pore defects. The nitrogen sites within NC-1000 not only facilitate FePc adsorption but also optimize the electron distribution at the Fe-N site. The FePc@NC-1000 composite material exhibits a significant number of active centers in the form of Fe-N 4 moieties, showcasing satisfactory ORR activity. Specifically, it demonstrates an onset potential of 0.99 V, a positive half-wave potential of 0.86 V, a large limiting current of 5.96 mA cm−2, and a small Tafel slope of 44.41 mV dec-1. Additionally, theoretical calculations and experimental results confirm the favorable performance and durability of zinc-air batteries assembled using FePc@NC-1000 , thereby highlighting their considerable potential for practical applications. Overall, this study provides a comprehensive exploration of the enhanced catalytic performance and increased stability of metal–organic framework-derived functional carbon nanomaterials as cost-effective, efficient, and stable catalysts for the ORR. [ABSTRACT FROM AUTHOR]

A series of high-activity MOF-on-MOF derived carbon nanomaterials are elaborately prepared via heteroepitaxial growth and subsequent calcination, which exhibit efficient oxygen reduction as well as Zn-air battery. [Display omitted] • A series of MOF-on-MOF heterostructures can be synthesized by.heteroepitaxial growth. • CoZnNC -2 endows abundant N -doping, dispersive Co nanoparticles, and large porosity. • The rational regulation of MOF-derived carbons is demonstrated for efficient ORR. The rational design and facile construction of hybrid metal–organic framework (MOF) with hierarchical nanostructures can motivate novel and multifunctional platforms to attain desirable performance. In this work, a new series of MOF-on-MOF heterostructures, including ZIF-8 / Zinc(II)-hexamethylenetetramine (ZIF-8/Zn-HMT) and ZIF-8 + ZIF-67/Zn-HMT-X (ZIF/Zn-HMT-X) , can be conveniently synthesized by heteroepitaxial growth. The as-obtained carbon nanosheets of CoZnNC-X are calcined from a CoZn MOF-on-MOF precursor, and they have abundant N -doping, dispersive Co particles, conductive network and large specific surface area, exhibiting efficient oxygen reduction reaction (ORR) as well as Zn-air battery (ZAB) performance. Among them, the most optimal CoZnNC-2 shows an onset potential of 0.95 V, high diffusion-limited current density of 5.41 mA cm−2, small Tafel slope of 59.1 mV dec−1 and excellent stability. Furthermore, the as-assembled ZAB based on CoZnNC-2 reveals a large power density of 113 mW cm−2 and a high specific capacity of 713.5 mAh g−1. Hence, the demonstrated work paves a brand-new route to rationally regulate MOF-derived carbon nanomaterials as efficient electrocatalysts for energy conversion and storage applications. [ABSTRACT FROM AUTHOR]

A structural and morphological transformation of a hydrogen-bonded organic framework (HOF) based on 1,3,5-benzentricarboxylic acid (H 3 BTC) is observed. With the introduction of metal cations, especially Co(II) ion, these weaker hydrogen bonds linked in this bulk HOF of BTC can be easily broken to obtain the ultrathin wire-shaped product, denoted as Co-Fiber. That is mainly for the reason that the divalent cobalt ions with modest polarity exhibit moderate disturbance and destruction to H-bonding networks. Following calcination and phosphatization, abundant HOF-derived porous carbon-coated CoP particles in CoP/NCNT/PC inherit the morphology of Co-Fiber and endow with in-situ formed N-doped multi-walled carbon nanotubes. Initial electrochemical activation of the CoP/NCNT/PC catalyst promotes the formation of the electrocatalytically active species of cobalt oxyhydroxide for efficient oxygen evolution reaction (OER) in 1.0 M KOH aqueous solution. The obtained CoP/NCNT/PC composite exhibits an outstanding OER performance with the low overpotential of 282 mV at 10 mA cm−2, the relatively small Tafel value (103.7 mV dec−1), and the long-term durability remaining 90.5% over 10 h. The reasonable and facile method to synthesize low-cost, efficient and robust CoP/NCNT/PC shows great potential to substitute noble-metal based electrocatalysts for OER. Meanwhile, it will provide a new way for the application of HOF-derived carbon nanomaterials in the new energy field. [Display omitted] • A structural and morphological change of a hydrogen-bonded organic framework is observed. • Divalent metal ions show moderate disturbance and destruction to H-bonding networks. • HOF-derived carbon-coated CoP particles exhibit a satisfactory oxygen evolution. [ABSTRACT FROM AUTHOR]

The development of highly efficient and low-cost electrocatalysts for large-scale hydrogen evolution reaction (HER) is great important but remains a significant challenge. Transition-metal phosphides (TMPs) have attracted intense attention as promising non-noble-metal HER electrocatalysts due to their unique electronic properties and high intrinsic catalytic activities. Herein, we directly grew Ni X Co 2-X P nanorod wrapped with N-doped carbon shell on 3D Ni foam to fabricate a self-supported electrode with core-shell nanorod array morphology. The obtained hybrid electrode exhibits remarkable electrocatalytic HER activity over a wide pH range with low overpotentials of 121 mV and 181 mV to obtain the current density of 200 mA cm−2 in 0.5 M H 2 SO 4 and 1 M KOH electrolytes, respectively, which is comparable to that of the current state-of-the-art Pt/C electrocatalyst. The experimental results indicate that the elaborate architectural superiority and compositional synergy of this hybrid electrode give rise to the boosted HER performance. A self-supported NC@Ni X Co 2-X P/NF electrode comprising of Ni X Co 2-X P nanorods core covered with N-doped carbon shell grown on porous Ni foam skeleton is fabricated and shows superior HER performance over a wide pH range. [Display omitted] • Heterostructure of N-doped carbon@Ni X Co 2-X P core-shell nanorod arrays is facilely prepared. • The strategy of morphological and electronic dual regulation is used. • The hybrid electrode exhibits remarkable electrocatalytic HER activity over a wide pH range. • Elaborate architectural superiority and compositional synergy lead to the enhanced HER performance. [ABSTRACT FROM AUTHOR]

Rational design of oxygen reduction reaction (ORR) electrocatalysts with indestructible active sites for high-performance Zn-air batteries (ZABs) remains a significant challenge. Herein, we achieve an innovative active site design by encaging Co nanoparticles within the Co−N 4 atomic sites-dispersed graphite nanopocket (Co SAs-NPs /NC), leading to outstanding alkaline ORR activity and stability, and consequently ultra-high power density of 193.8 mW cm–2 and specific capacity of 819.1 mAh g Zn –1 at 10 mA cm–2 of a primary ZAB assembled, along with impressive power density of 73.4 mW cm–2 and charging/discharging stability up to 110 cycles of a flexible solid-state ZAB. Theoretical calculations unveil the enhanced ORR kinetics can be traced to the significantly optimized local electronic structure of Co−N 4 sites with upshifted d-band center and reduced energy barrier of rate-limiting step by the encaged Co nanoparticle. This study showcases a creative conformational design for guiding the construction of valid synergy in hybridized metal/single-atom catalysts. [Display omitted] ● A MOF-based ligand exchange strategy is designed for the synthesis of Co SAs-NPs /NC. ● Co NP encaged in atomic Co-dispersed graphite nanopocket is found in Co SAs-NPs /NC. ● Co SAs-NPs /NC owns alkaline electrocatalytic ORR performance exceeding that of Pt/C. ● High-performing liquid and solid-state flexibile Zn-air batteries are both gained. ● DFT results verify the strong electronic synergy between Co-NPs and Co-SAs for ORR. [ABSTRACT FROM AUTHOR]

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. Herein, we present a stepwise approach for constructing 3-dimensional porous carbon foam pretreated via glutaraldehyde cross-linking and decorated with highly dispersed Mo 2 C (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/oxygen evolution reaction, respectively. [Display omitted] • The chitosan hydrogel with oriented structure is built by using a stepwise strategy. • The 3-dimensional porous carbon foam is calcined from chitosan hydrogel. • The carbon foam with typical transition metal catalysts shows better water splitting. [ABSTRACT FROM AUTHOR]

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 Mo 2 C 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 H 2 SO 4 and 100.1 mV in 1.0 M KOH to reach a current density of 10 mA cm−2, which is attributed to ultrasmall Mo 2 C, 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. Image 1 • Use a stepwise conversion to prepare bimetallic ZnMo-MI between Zn-MI and Na 2 MoO 4. • Mo 2 C nanoparticles are embedded in N-doped carbon calcined from ZnMo-MI at 1000 °C • The HER performance is attributed to the synergies of Mo 2 C, Mo, N-doped carbon. [ABSTRACT FROM AUTHOR]

The non-platinum metal-nitrogen-carbon (M-NC) system is a class of highly active oxygen reduction reaction (ORR) electrocatalysts that are well known and widely used in fuel cell applications. Herein, one simple synthesizing method of efficient M-NC electrocatalysts is proposed by the direct pyrolysis of a pretreated core-shell structure of ZnO@ZIF-8 containing metal-ammonia complex (MAC, [M(NH 3) x n+) from the polydisperse self-sacrificing MOF-5 cubes. The as-pyrolyzed M-NC (M = Co, Ag, Cu, and Ni) electrocatalysts showcase high electrocatalytic ORR activity in an alkaline medium. Among them, Co-NC catalyst exhibits an excellent ORR performance where its E 1/2 = 0.80 V, J L = 5.88 mA cm−2, as well as Tafel slope of 67.0 mV dec−1 are close to commercial Pt/C and Ag-NC, better than the other two catalysts of Cu-NC and Ni-NC. Impressively, zinc-O 2 batteries assembled with M-NC materials exhibit the better discharge performance, and have great potential in the practical energy conversion and storage. The experimental demonstration of metal-based nanoparticles and active M-N sites in the carbonaceous matrix can be efficiently used to promote the ORR activity, which is derived from a synergistic contribution of its particular hollow structure, large specific surface area, rich M-N active sites, and high degree of graphitization. This attractive preparation approach provides us a powerful contribution to the construction of high-performance carbon-based ORR electrocatalysts. Herein, a series of high-performance non-precious TM-based M-NC catalyst for ORR are successfully obtained by direct pyrolysis of a MAC-impregnated core-shell structure synthesized from the self-sacrificing cube-shaped MOF-5 precursors. The as-pyrolyzed M-NC (M = Co, Ag, Cu, and Ni) electrocatalysts showcase a high electrocatalytic ORR activity in an alkaline medium due to metal-based nanoparticles and active M-N sites in the carbonaceous matrix. Image 1 [ABSTRACT FROM AUTHOR]

In this work, we demonstrated a facile strategy to fabricate paintbrush-like Co Doped Cu 3 P architecture grown on porous copper foam (Co-Cu 3 P/CF), which was obtained from cation exchange reaction followed by a pyrolysis assisted phosphorization step. Co-Cu 3 P/CF showed outstanding electrocatalytic performance for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 1 M NaOH solution, affording low overpotential of 270 mV to reach the current density of 50 mA cm−2 for OER. As for HER, a low overpotential of 200 mV is required to obtain the same catalytic current density. The overall water electrolyzer by using Co-Cu 3 P/CF as both anode and cathode showed a low cell voltage of 1.55 V to deliver 10 mA cm−2. The excellent electrocatalytic performance of Co-Cu 3 P/CF could be ascribed to its paintbrush-like hierarchical architecture, offering plentiful of active sites and accelerating electrolyte penetration, the presence of Co dopant also could rationally modify its electronic properties, and thus lead to the synergetic effects. • Co-Cu 3 P architectures in-situ grown on copper foam was prepared via a facile method. • The paintbrush-like morphology of Co-Cu 3 P is beneficial for exposing plentiful of catalytic active sites. • The overall water splitting cell showed a low cell voltage of 1.55 V to deliver 10 mA cm−2. • Co dopants play a vital role in enhancing the catalytic performance of Co-Cu 3 P. [ABSTRACT FROM AUTHOR]

Nanostructured transition-metal phosphides (TMPs) have recently emerged as a new family of non-noble-metal catalysts to drive water splitting due to their unique electronic and redox properties. However, most progress focused on developing mono-metal phosphide nanostructures. In this work, a facile template-based method and low-temperature phosphorization process are proposed to fabricate self-supported Ni-based bimetallic phosphide encapsulated in amorphous carbon by using metal-organic framework (MOF) as the precursor and three-dimensional nickel foam (NF) as the support, which is termed as Ni 2 P-Co 2 P@C/NF. This composite demonstrates remarkable electrocatalytic activities towards both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolyte (1 M KOH, pH 13.6), affording low overpotentials of 290 and 167 mV to deliver the current density of 50 mA cm−2 for OER and HER, respectively, preceding the majority of recently reported MOFs-derived TMPs. This excellent performance is considered as the results of its large catalytic surface area, concerted synergy from composited structure as well as the increased electrical conductivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hollow MOF-on-MOF nanostructure could be obtained by balanced etching and growth rate. • FeNi 3 -NC-700 endows rich N-doping, dispersive FeNi 3 particles, and large porosity. • The synergistic effect between Ni and Fe species greatly promotes water oxidation. To achieve the carbon peak and neutrality targets, the facile synthesis of highly active and robust catalysts for efficient oxygen evolution reaction (OER) is urgently demanded. Herein, a series of metal–carbon nanomaterials (FeNi 3 -NC-T , T = 600–1000 °C) with the hollow N-doped carbon nanorod incorporated FeNi 3 nanoparticles are reasonably prepared via balancing epitaxial growth and etching rate. These synthesized OER catalysts exhibit effective synergies of multiple components, large specific surface area, high conductivity, abundant exposed active sites, and intrinsic activity enhanced by carbon confinement and interconnected nanostructure. Among them, the optimized FeNi 3 -NC-700 only requires low overpotentials of 262/327 mV to reach the current density of 10/50 mA cm−2 in an alkaline medium, which is obviously better than these control samples. Owing to the aforesaid structural virtues, it exhibits high activity and good stability, fast catalytic kinetics and easy formation of active species evidenced by in-situ experiments as well as theoretical calculations. This study would provide a new idea for the easy fabrication of multifunctional MOF derivatives in electrochemistry with the desired properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • The controllable crystal growth of In-based MIL-68-NH 2 is easily achieved by using pyridine. • Fe phthalocyanines could be effectively embedded into porous N-doped carbon nanomaterials. • The rationally designed electrocatalyst of FePc@NCNS shows higher activity and stability compared to Pt/C. The rational design and preparation of atomic-level dispersed non-platinum catalysts to achieve efficient oxygen reduction reactions (ORR) is worth exploring for clean energy conversion and storage technology. Herein a simple self-templating strategy is demonstrated to obtain MIL-68-NH 2 -x series using pyridine as a surfactant to realize micron-scale to nanosized conversion. Among them, the as-prepared MIL-68-NH 2 -300 owns a large specific surface area and abundant pore defects after thermal treatment, which can effectively adsorb and anchor Fe phthalocyanines (FePc). In this case, MOF-derived N-doped carbon nanosticks coupled with FePc molecules (FePc@NCNS) exhibit an excellent electrocatalytic ORR activity with a positive half-wave potential (0.904 V), a large diffusion-limited current density (6.17 mA cm−2) and a high current retention after 20 h (95.7%). Furthermore, the high performance of ORR is confirmed by the relevant theoretical calculations on O 2 adsorption ability. These above results will pave the way for MOF-derived carbon nanomaterials with specific morphological dimensions for high-performance energy conversion and storage. [ABSTRACT FROM AUTHOR]

In this work, we report 1-dimensional hexagonal tubular InOF-25 that can be tuned by surfactant and is morphologically altered under hydrolysis. Followed by MX n encapsulation and pyrolytic process, the banded InOF-25 can be thermally converted into strip-like carbon nanoribbons containing ultrafine noble metal nanoparticles (M@CNR). Due to the abundant active sites and a small quantity of highly active noble metal nanoparticles in the protective carbon nanobelts, the obtained M@CNR series compounds as cathode catalysts show efficient ORR performance and good electrochemical stability as well as Zn-air battery. [Display omitted] • 1. A tubular indium-based framework (InOF-25) can be adjusted by surfactant. • 2. Strip-like carbon nanoribbons with ultrafine noble metal nanoparticles (M@CNR) can be obtained. • 3. The M@CNR compounds own large specific surface areas and highly active noble metal nanoparticles. • 4. The Pd@CNR shows the satisfying ORR performance and practical applicability for Zn-air battery. In pursuit of sustainable and eco-friendly energy output, fuel cells are well-recognized as the most promising candidates in clean energy conversion and storage technology. Noble metal-based nanomaterials have long been regarded as the most efficient electrocatalysts for the oxygen reduction reaction (ORR) in terms of activity, selectivity, and stability. Here, we propose a self-template strategy where a type of hexagonal tubular InOF-25 could be tuned by adding a different amount of surfactants. Owing to the suitable pore size, these fabricated X-CTAB@InOF-25 (X = 50–300) series are used as precursors to encapsulate a series of discrete metal complexes, including Ag(NH 3) 2 +, AuCl 4 -, PdCl 4 2-, and PtCl 6 2-. Then, the as-prepared carbon nanoribbons doped with precious metals (M@CNR , M = Pd, Pt, Ag, Au) exhibit good performance in the electrocatalytic ORR as well as Zn-air battery due to their large surface area, rich active sites, and extremely active noble metal nanoparticles. Among them, the most optimal Pd@CNR shows an onset potential of 0.94 V vs. RHE, high diffusion-limited current density of 5.87 mA cm-2, small Tafel slope of 51.74 mV dec-1, and satisfying stability with current retention of 95.4% after 10 h. Meanwhile, these obtained M@CNR as cathode catalysts are modeled and proved by the theoretical calculation with strong oxygen adsorption for efficient ORR. In this context, the main issues, large overpotential required for ORR and fast degradation of the electrocatalysts, impair practical application, which could be relieved by the active noble metals well-protected by carbon nanomaterials from the rational design and preparation of precursors. [ABSTRACT FROM AUTHOR]

The overall water splitting is severely limited by the sluggish oxygen evolution reaction (OER), which further restricts the large-scale production of hydrogen for sustainable energy. These transition metal-based (oxy)hydroxides (TM(O)OH) are recognized as the most efficient non-noble electrocatalysts for OER, but the rational design and fabrication of TM(O)OH species remain a big challenge. Here we have synthesized a porous metal-organic framework (MOF, CoHKUST-1), and the rapid degradation of this MOF itself in alkaline solution is intrinsically stemmed from the metastable nature of the Co–O coordination bonds in the Co-based paddle wheel. By simply applying an electric potential, these synthesized Co-MOFs can be decomposed into the 2-dimensional nanosheet structure mainly consisting Co(OH) 2 and CoOOH. The resulting CoO x H y nanosheets exhibit excellent OER performance to reach an overpotential of only 344 mV at 10 mA cm−2, and its Tafel slope is calculated to be 66.4 mV dec−1 indicating the fast reaction kinetics. The structural and morphological evolution under electrolysis is further proposed and evidenced by relevant physicochemical characterizations and theoretical calculations. The demonstrated work proves a feasible strategy for electrochemical design and fabrication of 2-dimensional TM(O)OH nanosheets for efficient water oxidation, which can be further applied in the future energy applications. [Display omitted] • A porous CoHKUST-1 undergoes the degradation by electrolysis in alkaline solution. • The electrochemical evolution of CoHKUST-1 is stemmed from the metastable Co–O bond. • These decomposed 2-dimensional CoO x H y is conducive to efficient water oxidation. [ABSTRACT FROM AUTHOR]

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-N x 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. [Display omitted] • A bottom-up method is proposed to prepare hollow porous Co,N-doped carbon materials. • The obtained MOF-derived core-shell structure is endowed with decent surface area. • The nitrogen-carbon network anchored by rich dispersed Co-N x sites is obtained. • The Co,N-doped carbon materials show an excellent ORR activity for Zn-air battery. [ABSTRACT FROM AUTHOR]

• A new Ni based-MOF (BMM-13) is synthesized by adopting an easy solvothermal method. • Hollow Fe-BMM-13 can be prepared by in-situ etching of BMM-13 with Fe(III) cations. • Fe-BMM-13 derived hollow carbide with embedded FeNi 3 can achieve an efficient OER. 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 FeNi 3 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-800–5 sample, 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. In this work, 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 FeNi 3 alloy nanoparticles (NiFeC). The as-obtained NiFeC-800–5 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. Image, graphical abstract [ABSTRACT FROM AUTHOR]

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 SiO 2 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. Image 1 • Abundant nanotube coated ordered macroporous carbon matrix FeNi-MNC is prepared. • FeNi-MNC remains ultrahigh Fe/Ni-N contents by the co-catalysis of Fe and Ni species. • FeNi-MNC is active both for OER (η = 298 mV) and ORR (E1/2 = 0.834 V). [ABSTRACT FROM AUTHOR]

In the field of renewable energy, the core of advanced materials lies in the efficiency for the electrocatalytic and photoelectrochemical overall water splitting. However, in hydrogen evolution reaction (HER), there is a lack of electrocatalysts based transition metals of high-performance and natural-abundance, and thus there is a formidable challenge for large-scale application. Therefore, molybdenum carbide (Mo 2 C) based catalysts and their composites are regarded as a most promising and replacement noble metal electrocatalyst for the HER in different media about all pH. In this work, the preparation of ultra-fine Mo 2 C nanoparticles, which uniformly implant into hollow N-doped carbon polyhedrons (Mo 2 C@HNCPs) by adopting MOF-assisted self-sacrifice template approach, is proposed. Mo 2 C@HNCPs showcases suitable catalytic activity and feasible stability toward HER in both media such as acidic and alkaline solutions. The as-prepared Mo 2 C@HNCPs exhibits effective and fast response from the HER region with nearly 0.0 V onset overpotentials, only requiring 89 mV (0.5 M H 2 SO 4 media) and 87 mV (1.0 M KOH media) overpotential to reach 10 mA cm−2 and cycling stability (<5% performance loss after 10 h). Such distinctive activity of HER is mainly imputed to the poly-dispersion of the ultra-fine Mo 2 C nanoparticles and its synergistic contribution of rich nitrogen doping, unique hollow morphology, and abundant active sites at the heterostructures. The synthesis of ultra-fine Mo 2 C nanoparticles is uniformly embedded into hollow N-doped carbon polyhedrons (Mo 2 C@HNCPs) by a MOF-assisted self-sacrifice template approach. As the HER electrocatalyst, Mo 2 C@HNCPs shows better catalytic activity and feasible stability toward HER in both acidic and alkaline media. Such HER activity is attributed to the ultra-fine Mo 2 C nanoparticles and synergistic contribution of nitrogen doping, unique hollow structure, and abundant active sites at the heterostructures. Image 1 • A new approach of the MOF-assisted self-sacrifice template is successfully obtained and outlined. • Ultra-fine Mo 2 C nanoparticles are uniformly embedded into hollow N-doped carbon polyhedrons by a simple thermal treatment. • The as-obtained catalyst (Mo 2 C@HNCPs) is of better HER performance and long-term stability in the real application. [ABSTRACT FROM AUTHOR]