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In response to the escalating environmental impact of fossil fuels, there's a growing demand for clean energy solutions, particularly efficient metal-air batteries. Metal-air batteries are promising for energy storage, boasting abundant materials and low cost. However, their efficiency is hindered by slow oxygen reduction and evolution reactions. Synthesizing effective and stable oxygen electrocatalysts is crucial for enhancing battery performance. Here, this work used a simple solvothermal method to synthesize Iron–Cobalt metal-organic framework (FeCo-MOF), Manganese–Iron–Cobalt metal-organic framework (MnFeCo-MOF), and their composites with (1, 3, and 5) wt% rGO and characterized via using XRD, SEM, FTIR, and Raman spectroscopy. Electrochemical testing was conducted in 1 M KOH solution for both OER and ORR. The 3 wt% rGO MnFeCo-MOF shown the lowest overpotential of 54 mV at 10 mA/cm2 and the lowest Tafel slope of 63.4 mV/dec, with highest current density of 79.42 mA/cm2 at 25 mV/s scan rate for OER indicating excellent electrocatalytic activity superior to already reported in literature due to synergistic effect of Mn, Fe, Co, and rGO facilitating rapid electron transfer and more active sites. The 3 wt% rGO MnFeCo-MOF exhibited the halfwave potential of 0.74 V for ORR showing excellent activity comparable to commercial catalysts Pt/C. The lower potential gap ΔE 0.66 V from the overall combined plot of OER/ORR shows efficient and stable bifunctional activity of the 3 wt% rGO MnFeCo-MOF. These exceptional electrocatalytic properties pave the way for future advancements in metal-air batteries. [Display omitted] • FeCo-MOF, MnFeCo-MOF, and their composites with rGO were synthesized solvothermaly at 120 °C. • 3 wt% rGO MnFeCo-MOF showed lowest TAFEL slope 63.4 mV/dec and overpotential of 54 mV at 10 mA/cm2 for OER. • 3 wt% rGO MnFeCo-MOF for ORR has a halfwave potential of 0.74 V. • Exhibited excellent stability studied via chronopotentiometry experiment. • Synergic effect among rGO and Mn, Fe, Co MOF active sites. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting for sustainable hydrogen and oxygen production have shown enormous potentials. However, this method needs low‐cost and highly active catalysts. Traditional nano catalysts, while effective, have limits since their active sites are mostly restricted to the surface and edges, leaving interior surfaces unexposed in redox reactions. Single atom catalysts (SACs), which take advantage of high atom utilization and quantum size effects, have recently become appealing electrocatalysts. Strong interaction between active sites and support in SACs have considerably improved the catalytic efficiency and long‐term stability, outperforming their nano‐counterparts. This review's first section examines the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER). In the next section, SACs are categorized as noble metal, non‐noble metal, and bimetallic synergistic SACs. In addition, this review emphasizes developing methodologies for effective SAC design, such as mass loading optimization, electrical structure modulation, and the critical role of support materials. Finally, Carbon‐based materials and metal oxides are being explored as possible supports for SACs. Importantly, for the first time, this review opens a discussion on waste‐derived supports for single atom catalysts used in electrochemical reactions, providing a cost‐effective dimension to this vibrant research field. The well‐known design techniques discussed here may help in development of electrocatalysts for effective water splitting. [ABSTRACT FROM AUTHOR]

Summary: A significant interest in the exploration of clean and renewable alternative energy resources has been observed in recent years to combat environmental pollution and energy shortages for a sustainable future. In this regard, hydrogen is clean, energy‐rich fuel with unlimited potential. It can be produced via water‐splitting process using the most abundant resources on earth, that is, water and solar/electrical energy. Metal‐organic frameworks (MOFs) are a category of porous crystalline materials with well‐organized structures and unique catalytic, optical, and electrical properties. MOFs and MOF‐derived materials have proved to be excellent catalysts for water‐splitting both by electrochemical and photoelectrochemical (PEC) routes. Furthermore, photochemical and electrochemical capabilities of these MOFs can be fine‐tuned to maximize their performance by modification in the bandgap, surface area, current density, electrochemical active surface area, and overpotential, through tailoring of the organic ligands and/or metal centers. A number of works have been dedicated to this quest resulting in promising and very effective results. Such as for photoelectrocatalysis, a composite nanorod array of TiO2/Co‐MOF acting as photoanode achieved one of the highest photocurrent densities of 2.93 mA/cm2 at 1.23 V (vs reverse hydrogen electrode [RHE]). In another study, MOF‐derived Co3C‐3/TiO2 photoanode attained the photocurrent density of 2.6 mA/cm2 at 1.23 V vs RHE. For electrocatalysis, Fe2O3/Ni‐MOF‐74 exhibited oxygen evolution reaction overpotential of 264 mV to reach 10 mA/cm2 of current density with a low Tafel plot of 48 mV/dec. Another novel material derived from MOF, MoO2‐PC‐rGO displayed a Tafel Plot of 41 mV/dec. Even though this field is in its infancy phase, it is attracting increased attention for promising results suggesting extraordinary potential for practical applications. Focus of this review article is on the overview of the development of MOFs for application in electrocatalytic and photoelectrocatalytic water‐splitting for hydrogen production. This review intends to provide a timely reference and insight for the advancement in catalysts based on MOFs for practical electrochemical and PEC water‐splitting in a clear and comprehensive manner. Starting with the brief introduction, fundamentals, factors affecting catalytic efficiency and evaluation parameters of water‐splitting are summarized followed by synthesis strategies and recent progress made by MOF‐based catalysts for PEC and electrochemical water‐splitting. [ABSTRACT FROM AUTHOR]

A considerable concern in exploring clean, efficient, and renewable energy resources to effectively replace fossil fuels and to combat the environmental problems and energy scarcities for a sustainable future has been observed. In this context, hydrogen is a clean, renewable, energetically efficient fuel with infinite potential for the future, which can generate a large amount of energy through the electrocatalytic splitting of earth‐abundant water resources. Noble metals, owing to their extraordinary efficiency and stability, are state‐of‐the‐art catalysts for the oxygen evolution reaction (OER) process. However, their scarcity and high cost hamper their commercialization. To replace these expensive noble‐metal‐based materials, researchers are extensively working on the development of cost effective, stable, conductive, and efficient non‐noble metal based materials such as transition metal oxides, borides, nitrides, sulfides, phosphides, selenides, perovskites oxides, and layered double hydroxides, where the incorporation of heteroatoms improves the electrocatalytic activity by modifying the electronic structure and enhances the conductivity and stability. In the case of transition‐metal based metal organic frameworks (MOFs) and MOF‐derived materials, the unique structure of MOFs with a high surface area and porosity, as well as rich redox chemistry of transition metals, leads to excellent response towards the OER process. Moreover, direct utilization of carbonaceous materials or making their composites with transition metals not only enhances the conductivity due to their conductive nature but also promotes stability by strongly binding with the electrocatalyst. Owing to the presence of functional groups on the surface or through different interactions, they provide multiple paths for facile electron and ion transport due to the sheet/network like structure, which help in the fine dispersion of electrocatalyst due to high surface area, prevent agglomeration, and in turn results in improved electrocatalytic activity. Besides these advances, a) there is still a need for a thorough understanding of reaction mechanism via in situ spectroscopic techniques to further optimize the composition and design of electrocatalyst to get desired results, b) the stability of the materials should be further enhanced to practically utilize synthesized material under harsh conditions without degradation, and c) the utilization of these optimized OER catalysts in a solar cell to consume solar energy (renewable energy source), remains a key requirement of the modern era. [ABSTRACT FROM AUTHOR]

In this research, electrocatalytic activity of cobalt benzene tricarboxylic acid metal organic framework (Co BTC MOF) and its reduced graphene oxide based composites (rGO/Co BTC) were investigated in an alkaline media for the methanol oxidation reaction (MOR). Metal Organic frameworks (MOF) and their composites were solvothermally prepared and characterized via FTIR, EDX, SEM and XRD. Electrochemical studies were performed by cyclic voltammetry, electron impedance spectroscopy, chronoamperometry and cyclic stability. Among all the prepared composites, 1 wt % rGO/Co BTC MOF (1.07 mg cm−2) demonstrated a promising current density of 130 mA cm−2 at 1.59 V vs. RHE, a tafel slope of 83.6 mV dec−1 and resistance of 14.75 Ω in 1 M NaOH/ 2 M methanol solution showing much better performance than state‐of‐the‐art Pt based materials. [ABSTRACT FROM AUTHOR]

• Fe-Co/NC with rGO electrocatalysts are derived by the pyrolysis method. • rGO as a support improves the catalytic performance and stability of MOF. • 5 wt% rGO@Fe-Co/NC exhibit overpotential for HER (-0.164 V) and OER (0.14 V) • The catalyst showed stability up to 24 h. This study focuses on the rational design and synthesis of catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). A two-step method is employed, where the catalysts are first designed through hydrothermal synthesis and then subjected to pyrolysis at 400 °C under an argon environment. The performance of the designed electrocatalyst Fe-Co/NC, along with its 1, 3, 5, and 7 wt% rGO-based composites, is compared against commercial catalysts, 5 wt% Pt/C, and IrO 2 , for HER and OER. From all of the synthesized electrocatalysts, the 5 wt% rGO@Fe-Co/NC electrocatalyst exhibits exceptional electrochemical activity with less overpotential for both HER (−0.164 V) and OER (0.14 V) in the presence of alkaline media. Furthermore, this composite remained stable for 24 h without any degradation. The improved electrocatalytic activity of the 5 wt% rGO@Fe-Co/NC composite compared to Fe-Co/NC can be attributed to the presence of support materials like rGO and the availability of nanoporous carbon containing iron and cobalt. This successful combination of doping and interface engineering holds significant promise in the design of advanced electrocatalytic materials for water-splitting processes. [ABSTRACT FROM AUTHOR]

This work utilized an innovative and economical remediation method to convert inexpensive waste feedstock into extremely useful catalysts. The procedure centered on polyethylene (PE), an easily accessible substance, and effectively transformed it at a mild temperature utilizing a new solvothermal technique, which entailed the reaction of sulfuric acid with PE chains at 120 °C. Throughout this process, the polymer experienced a pivotal cross-linking stage, resulting in its conversion into carbon materials when exposed to temperatures above 500 °C. To improve the catalytic characteristics, platinum (Pt) was effectively integrated into the resultant carbon matrix using the existing impregnation technique. Further, the catalyst's physicochemical properties were thoroughly analyzed utilizing SEM, FTIR, and XRD techniques. After that, the catalyst's performance was thoroughly evaluated in several electrocatalytic reactions, such as methanol oxidation, oxygen evolution and reduction reactions, and hydrogen evolution. The results of this investigation reveal the impressive electrocatalytic ability of the Pt/C catalyst made from waste plastic. It was found to be comparable to the best commercially available Pt/C catalysts in all the reactions that were examined. This research not only demonstrates the possibility of using waste plastic for catalyst production, but also serves as the first documented example, based on successfully converting waste plastic bags into Pt/C through the conventional Liquid Phase Reduction (LPR) process. This novel method has great potential for sustainable and ecologically responsible catalytic applications. • The waste plastic derived Pt/C catalyst was prepared by solvothermal method. • For MOR plastic derived Pt/C shows electrocatalytic activity of 96.74 mA/cm2 current density and 46 % stability. • For OER it attain a current density of 10 mA/cm2 at a potential of 1.65 V. • For HER achieve current density of 10 mA/cm2 at a low voltage of 39.1 mV. • For ORR it exhibits −2.80 mA cm⁻2 of current density and half potential of 0.86 V. [ABSTRACT FROM AUTHOR]

For metal air batteries the synthesis of highly efficient, sustainable, non-precious metal-based electrocatalysts with bifunctional catalytic activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are essential. In this work via simple hydrothermal method Cu MOF and its g-C 3 N 4 based composites are prepared and characterized via FTIR, XRD, SEM and EDX. The Cu MOF and the g-C 3 N 4 -based electrode can work synergistically to enhance the electrochemical process. The Cu MOF accepts electrons, and the g-C 3 N 4 -based electrode donates them. Consequently, improving electron transport between the electrode and oxygen molecule accelerates reaction kinetics. Further, via incorporating g-C 3 N 4 in Cu MOF makes the charge transfer between the electrode and electrolyte effective, making it a viable option for electrochemical devices. In stable states, Cu MOF with 5 wt% of graphitic carbon nitride has a low overpotential (389 mV/10 mA/cm2), a Tafel slope of 26.12 mV/dec, and high stability over 3600 s in 1 M KOH. EIS result showed that g-C 3 N 4 decreases charge transfer resistance by allowing electroactive species to contact the catalyst. Further, via three-electrode setup under nitrogen and oxygen conditions at different scan speeds ORR analysis is done. The composite Cu MOF (5 wt%) exhibits the maximum current density of 1.31 mA/cm2 at 0.05 mV /s scan rate in 1 M KOH, surpassing the original Cu MOF, which produced 1.09 mA/cm2. • Cu MOF and its g-C 3 N 4 based composites, synthesized via Hydrothermal method, and characterized via FTIR, XRD, SEM and EDX. • Electrochemical activity is tested in 1 M KOH via CV, EIS, CA and LSV. • For OER Cu MOF/ 5 wt% @ g-C 3 N 4 show low overpotential of 389 mV at 10 mA/cm2, 26.12 mV /dec (Tafel slope). • For ORR Cu MOF/ 5 wt% @ g-C 3 N 4 show an onset potential of 0.88 V vs RHE, and exhibit good stability after 1000 ORR cycles. [ABSTRACT FROM AUTHOR]

The main focus of this work is the development of nonprecious, highly effective, stable, and bifunctional electrocatalysts for water splitting. In this paper, a highly active electrocatalyst LSTN was designed, which is composed of LSTN (La 0.4 Sr 0.4 Ti 0.9 Ni 0.1 O 3-&) perovskite and graphitic carbon nitride (g-C 3 N 4) by sol-gel method followed by calcination at high temperature. XRD, SEM, EDX, and FTIR are the techniques used to characterize the prepared catalysts. In alkaline media, LSTN and g-C 3 N 4 hybrids exhibit exceptional electro-catalytic activity for water splitting. Specifically, 3 wt% g-C 3 N 4 @LSTN hybrid shows excellent electro-catalytic activity for both oxygen and hydrogen evolution reactions by offering a small overpotential of 62 mV and 148 mV at 10 mA cm-2, respectively. It also exhibits small values of the Tafel slope for oxygen evaluation reaction (OER) and hydrogen evaluation reaction (HER), which are 119 and 32 mVdec-1, respectively. Results showed that 3 wt% g-C 3 N 4 @LSTN hybrid is a highly active, stable, and economical electrocatalyst and proves to be the promising option for water splitting. • A novel electrocatalyst synthesized for OER and HER. • Electrocatalyst is prepared by sol-gel method followed by high temperature calcination. • 3 wt% g-C 3 N 4 @LSTN hybrid shows excellent electrocatalytic activity for HER and OER. • Tafel slope 62 mVdec-1 for HER and 142 mVdec-1 for OER. • Low overpotential values for OER and HER are 62 mV and 148 mV, respectively. [ABSTRACT FROM AUTHOR]

Cover Feature: Recent Advances in Electrocatalysis of Oxygen Evolution Reaction using Noble-Metal, Transition-Metal, and Carbon-Based Materials (ChemElectroChem 3/2021) Keywords: Electrocatalysts; Hydrogen production; Oxygen Evolution Reaction (OER); Activity parameters; Metal Organic Frameworks (MOFs) EN Electrocatalysts Hydrogen production Oxygen Evolution Reaction (OER) Activity parameters Metal Organic Frameworks (MOFs) 427 427 1 02/13/21 20210201 NES 210201 B The Cover Feature b illustrates noble-metal, transition-metal, and carbon-based compounds effectively utilized for oxygen evolution reaction electrocatalysis. Electrocatalysts, Hydrogen production, Oxygen Evolution Reaction (OER), Activity parameters, Metal Organic Frameworks (MOFs). [Extracted from the article]

This work describes electrocatalytic behavior of amiable and economical iron nickel 2-amioterephthalic acid metal organic framework (FeNiNH 2 BDC MOF) and its 2–6 wt % carbon nanotubes (CNTs) composites for oxygen evolution reaction (OER) in an alkaline media. Systematic structural and morphological analysis of solvothermally fabricated Iron (Fe) and Nickel (Ni) based MOF and their CNTs composites was carried out by Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Brunauer–Emmett–Teller (BET) and energy dispersive X-ray spectroscopy (EDX) techniques. Synergetic effect of bimetallic metal organic framework (MOF) and conductive CNTs support improves the catalytic response of MOF. FeNiNH 2 BDC-5 wt % CNTs composite demonstrated current density of 10 mA/cm2 at an over potential (η) 0.22 V and onset potential of 1.36 V vs RHE, comparable with RuO 2 state-of-the-art catalytic material for oxygen evolution reaction in a fuel cell. Furthermore, FeNiNH 2 BDC-5 wt % CNTs composite tafel slope of 68.50mV/dec and 0.67s−1 turnover frequency (TOF) ascertain it as a promising alternative candidate towards costly Pt, Pd, Ir and Ru based catalysts. Image 1 • FeNi MOF composites with carbon nanotubes were solvothermally synthesized. • Synthesized FeNi MOF-CNTs composites were studied as electrocatalysts for OER in alkaline medium. • FeNiNH 2 BDC-5 wt % CNTs composite exhibit superior catalytic activity towards OER. • Stability retained by samples was studied via chronoamperometry experiment. • Synergetic effect between CNTs support and bimetallic MOF catalyst exist. [ABSTRACT FROM AUTHOR]

The three dimensional anionic Mn(II)-Oxalate coordination polymer has excellent water oxidation catalytic activity that may offer some new guidance for the design and preparation of highly efficient oxalate based 3D coordination polymers of first row transition metals for WOC. A novel three dimensional coordination polymer {[Mn(ox) 3/2 ][bap].(H 2 O)} n , (1) (ox = oxalate, bap = N -benzyl-4-aminopyridinium) is reported in this work as an efficient electrocatalyst for oxygen evolution reaction (OER). 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based dispersion condition as well as interactions between the adjacent layers of anionic coordination polymer and N -benzyl-4-aminopyridinium were found necessary for the growth and stability of this architecture. Single crystal XRD, IR and elemental analysis confirmed the formation of compound (1). Morphology and thermal stability were evaluated by SEM and TG respectively. Electrochemical studies were carried out in a three-electrode system using 1 coated FTO as a working electrode using 0.1 M KOH solution. The electrochemical investigation showed that 1 produced a current density of 10 mAcm−2 at a relatively low overpotential (η = 404 mV) while a maximum current density of 62 mAcm−2 was achieved. A catalytic onset potential for OER was observed at 1.5 V (vs RHE) and needed overpotential of 258 mV. The catalyst offered a turnover frequency (TOF) of 0.06 s−1 for OER at 404 mV. Long-term stability measurements of 1 were recorded by using chronoamperometry, IR analysis and LS voltammograms for the pristine and post-catalytic 1 coated FTO electrodes that confirmed the durability of the catalyst. The fascinating electrochemical behaviour of 1 toward oxygen evolution reaction can be attributed to its 3D polymeric structure and represents 1 as a robust and efficient catalyst towards OER. [ABSTRACT FROM AUTHOR]