Bimetallic Cu/Fe MOF-Based Nanosheet Film via Binder-Free Drop-Casting Route: A Highly Efficient Urea-Electrolysis Catalyst

L-lysine and surfactant-assisted synthesis of NiCo bimetal oxides for electrochemical water splitting

In the present study, bimetallic oxides comprising nickel (Ni) and cobalt (Co) were synthesized using a facile hydrothermal method in the presence of CTAB and L-lysine. Their efficacy in catalyzing hydrogen production under alkaline conditions was assessed. Structural, vibrational, and morphological characteristics were analyzed utilizing X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) techniques. The SEM images revealed a needle-like shape which is due to the surfactant addition. The NiCo oxides exhibited the lowest onset potential of 83 mV for HER and 130 mV for OER under standard conditions. The catalysts needed a potential of 286 and 450 mV to attain a current density of 50 mA/cm2 along with Tafel slope values of 119 and 332 mV/dec for HER and OER, respectively. These results suggested that L-lysine as a surfactant is highly effective in the fabrication of NiCo bimetal oxides for electrolytic water splitting applications.

Iron-based electrode material composites for electrochemical sensor application in the environment: A review

This review explores the expanding role of electrochemical sensors across diverse domains such as environmental monitoring, medical diagnostics, and food quality assurance. In recent years, iron-based electrocatalysts have emerged as promising candidates for enhancing sensor performance. Notable for their non-toxicity, abundance, catalytic activity, and cost-effectiveness, these materials offer significant advantages. However, further investigation is needed to fully understand how iron-based materials' physical, chemical, and electrical properties influence their catalytic performance in sensor applications. It explores the overview of electrochemical sensor technology, examines the impact of iron-based materials and their characteristics on catalytic activity, and investigates various iron-based materials, their advantages, functionalization, and modification techniques. Additionally, the review investigates the application of iron-based electrode material composites in electrochemical sensors for real sample detections. Ultimately, continued research and development in this area promise to unlock new avenues for using iron-based electrode materials in sensor applications.

Synergy strategy of multi-metals confined in heteroatom framework toward constructing high-performance water oxidation electrocatalysts

The development of a low-cost, highly active, and non-precious metal catalyst for oxygen evolution reaction (OER) is of great significance. Multi-metallic catalysts containing Fe, Co, and Ni exhibit remarkable OER activity, while the specific contributions of each component and the synergistic effects in the ternary metal catalyst has remained elusive. In this work, we synthesized a series of S and N-doped mono-metallic, bi-metallic, and tri-metallic hollow carbon sphere electrocatalysts (M-SNC) with the goal of enhancing the catalysts OER activity and shedding light on the unique roles and synergistic effects of the various metals in the FeCoNi ternary metal catalyst. Our systematic analyses demonstrated the introduction of Fe effectively reduces the overpotential, Co accelerates the kinetics of OER, and the addition of Ni further improves the OER performance. Benefiting from the synergistic effects, the FeCoNi-SNC exhibits a low overpotential of 270 mV, with no morphological or structural changes after reaction, maintaining high activity for 72 h at 10 mA cm-2. Moreover, the assembled FeCoNi-SNC || Pt/C water electrolysis device operates for 65,000 s with minimal degradation, demonstrating its potential for practical application. This work presents a synergy strategy for the preparation of low-cost and highly efficient OER catalysts and further provides insights into the rational design and preparation of multicomponent catalysts.

Coordinated d-p hybridized hcp@fcc NiRu alloy doped by interstitial atoms for boosting urea-assisted simulated seawater electrolysis at industrial current densities

The production of hydrogen through seawater electrolysis has recently garnered increasing concern. However, hydrogen evolution reaction (HER) by alkaline seawater electrocatalysis is severely impeded by the slow H2O adsorption and H* binding kinetics at industrial current densities. Herein, a face-centered cubic/hexagonal close packed (fcc/hcp) NiRu alloy heterojunction was fabricated on Ni foam (N doped NiRu-inf/NF) by a low-temperature nitrogen plasma activation. Simultaneously, nitrogen atoms are introduced into the alloy to facilitate d-p hybridization. When N doped NiRu-inf/NF is integrated into a dual-electrode cell for urea-assisted seawater electrolysis, it achieves 100 mA cm-2 with an ultra-low voltage of 1.36 V and excellent stability. Density functional theory (DFT) verifies that the robust d-p hybridization among Ni, Ru and N exhibits more energy level matching for H2O molecule adsorption at the Ru sites, while simultaneously reducing the interaction between H* and Ni sites in N-doped NiRu-inf.

Recent advances and potential applications for metal-organic framework (MOFs) and MOFs-derived materials: Characterizations and antimicrobial activities

Microbial infections, particularly those caused by antibiotic-resistant pathogens, pose a critical global health threat. Metal-Organic Frameworks (MOFs), porous crystalline structures built from metal ions and organic linkers, initially developed for gas adsorption, have emerged as promising alternatives to traditional antibiotics. This review, covering research up to 2023, explores the potential of MOFs and MOF-based materials as broad-spectrum antimicrobial agents against bacteria, viruses, fungi, and even parasites. It delves into the historical context of antimicrobial agents, recent advancements in MOF research, and the diverse synthesis techniques employed for their production. Furthermore, the review comprehensively analyzes the mechanisms of action by which MOFs combat various microbial threats. By highlighting the vast potential of MOFs, their diverse synthesis methods, and their effectiveness against various pathogens, this study underscores their potential as a novel solution to the growing challenge of antibiotic resistance.

NiSe2/CeO2 catalysts from Ce-UiO-66 metal-organic skeletons and their electrocatalytic oxidation of methanol, urea and glycerol

Hydrogen is a viable alternative energy source to fossil fuels. In order to manufacture enough hydrogen to meet the needs of social growth, finding an alternate energy source that is more effective is essential. Electrochemical water cracking is a more appropriate method for producing hydrogen. The methanol oxidation reaction (MOR), urea oxidation reaction (UOR) and glycerol oxidation reaction (GOR) can be used to replace the anodic oxygen evolution reaction (OER) and indirectly accelerate the hydrogen evolution reaction (HER), which has the advantages of saving energy and reducing environmental pollution. In this study, Ni/CeO2 catalysts were prepared by thermal annealing of MOFs (Ce-UiO-66) containing nickel species and NiSe2/CeO2 nanocrystalline catalysts were obtained through the selenation reaction at different temperatures. The NiSe2/CeO2-450 °C catalysts exhibited superior catalytic performance for the MOR, UOR, and GOR. The MOR showed a peak current density of roughly 186.68 mA cm-2 and a low oxidation potential of around 1.34 V. Similarly, the UOR demonstrated a peak current density of approximately 142.28 mA cm-2 and a low oxidation potential of around 1.32 V. Furthermore, the GOR exhibited a peak current density of approximately 82.56 mA cm-2 and a low oxidation potential of around 1.37 V. NiSe2/CeO2-450 °C could improve electrocatalytic performance for the MOR, UOR, and GOR, which is attributed to the more active sites that were exposed as a result of utilizing MOFs (Ce-UiO-66) as a precursor. Additionally, selenation increased the ability to transfer electrons. This research is crucial for the production of inexpensive, easily accessible transition metals in place of expensive noble metals, for the reduction of wastewater pollution from methanol and urea, and for the creation of effective anodic oxidation electrocatalysts.

1D/2D core-shell structure Ni-Mo-S@NiFe LDH grown on nickel foam: a bifunctional electrocatalyst for efficient oxygen evolution and urea oxidation reactions

The construction of bifunctional catalysts for the oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is important for accelerating the development of the hydrogen economy. Herein, a novel three-dimensional core-shell heterostructure (Ni-Mo-S@NiFeLDH/NF) was prepared by vertically growing NiFe layered double hydroxide (NiFe LDH) nanosheets on nickel foam (NF)-supported arrays of Ni-Mo-S (Ni3S2, Ni0.96S, Mo2S3) nanorods via a hydrothermal-sulfide-hydrothermal process. Benefiting from the unique core-shell structure with numerous exposed active sites, the optimized Ni-Mo-S@NiFe LDH/NF shows excellent OER/UOR activity, with an overpotential of only 274 mV for OER to reach 100 mA cm-2 and 1.318 V for UOR to reach 10 mA cm-2. Moreover, the assembled Ni-Mo-S@NiFe LDH||Pt/C urea electrolytic system requires only 1.348 V to achieve 10 mA cm-2, as much as 159 mV lower than pure water electrolysis. This work provides an idea for researching NiFe LDH-based OER/UOR bifunctional catalysts.

Metal-ion doping in metal-organic-frameworks: modulating the electronic structure and local coordination for enhanced oxygen evolution reaction activity

The doping of metal-organic frameworks (MOFs) with metal-ions has emerged as a powerful strategy for enhancing their catalytic performance. Doping allows for the tailoring of the electronic structure and local coordination environment of MOFs, thus imparting on them unique properties and enhanced functionalities. This frontier article discusses the impact of metal-ion doping on the electronic structure and local coordination of MOFs, highlighting the effects on their electrocatalytic properties in relation to the oxygen evolution reaction (OER). The fundamental mechanisms underlying these modifications are explored, while recent advances, challenges, and prospects in the field are discussed. In addition, experimental techniques that can be applied to tackle the realization of effective metal-ion doping of MOFs are also noted briefly.

Amorphous and defective Co-P-O@NC ball-in-ball hollow structure for highly efficient electrocatalytic overall water splitting

Electrochemical water splitting using hollow and defect-rich catalysts has emerged as a promising strategy for efficient hydrogen production. However, the rational design and controllable synthesis of such catalysts with intricate morphology and composition present significant challenges. Herein, we propose a template-engaged approach to fabricate a novel ball-in-ball hollow structure of Co-P-O@N-doped carbon with abundant oxygen vacancies. The synthesis process involves the preparation of uniform cobalt-glycerate (Co-gly) polymer microspheres as precursors, followed by surface coating with ZIF-67 layer, adjustable chemical etching by phytic acid, and controllable pyrolysis at high temperature. The resulting ball-in-ball structure offers a large number of accessible active sites and high redox reaction centers, facilitating efficient charge transport, mass transfer, and gas evolution, which are beneficial for the acceleration of electrocatalytic reaction. Additionally, density functional theory (DFT) calculations indicate that the incorporation of oxygen and the presence of Co-P dangling bonds in CoP significantly enhance the adsorption of oxygenated species, leading to improved intrinsic electroactivity at the single-site level. As a sequence, the titled catalyst exhibits remarkable electrocatalytic activity and stability for water splitting in alkaline media. Notably, it only requires a low overpotential of 283 mV to achieve a current density of 10 mA cm^-2 for the oxygen evolution reaction. This work may provide some new insights into the design of complex hollow structures of phosphides with abundant defects for energy conversion.

Cu@Fe-Redox Capacitive-Based Metal-Organic Framework Film for a High-Performance Supercapacitor Electrode

A metal-organic framework (MOF) is a highly porous material with abundant redox capacitive sites for intercalation/de-intercalation of charges and, hence, is considered promising for electrode materials in supercapacitors. In addition, dopants can introduce defects and alter the electronic structure of the MOF, which can affect its surface reactivity and electrochemical properties. Herein, we report a copper-doped iron-based MOF (Cu@Fe-MOF/NF) thin film obtained via a simple drop-cast route on a 3D-nickel foam (NF) substrate for the supercapacitor application. The as-deposited Cu@Fe-MOF/NF electrodes exhibit a unique micro-sized bipyramidal structure composited with nanoparticles, revealing a high specific capacitance of 420.54 F g^-1 at 3 A g^-1 which is twice compared to the nano-cuboidal Fe-MOF/NF (210 F g^-1). Furthermore, the asymmetric solid-state (ASSSC) supercapacitor device, derived from the assembly of Cu@Fe-MOF/NFǁrGO/NF electrodes, demonstrates superior performance in terms of energy density (44.20 Wh.kg^-1) and electrochemical charge-discharge cycling durability with 88% capacitance retention after 5000 cycles. This work, thus, demonstrates a high potentiality of the Cu@Fe-MOF/NF film electrodes in electrochemical energy-storing devices.

Quasi-Cu-MOFs: highly improved water stability and electrocatalytic activity toward H2O2 reduction among pristine 3D MOFs

QHKUST-1 calcined at 250 °C for 1 h maintains the perfect octahedral morphology of HKUST-1 and exhibits superior moisture stability and enhanced electrocatalytic activity compared to the original water-sensitive HKUST-1.

In situ growth of bimetal–organic framework-derived phosphides on conductive substrate materials as bifunctional electrocatalysts for overall water splitting

CoFeP/NF was synthesized in situ on porous Ni foam by electrodeposition and solvothermal methods, showing excellent electrocatalytic performance.

Acetate promotes the formation of NiRu/NiO towards efficient hydrogen evolution

The introduction of acetate in the precursor of metal-organic frameworks (MOFs) turns the final product from MOFs to NiRu/Ni(OH)₂. Followed by annealing treatment, the obtained NiRu/NiO catalyst exhibits high hydrogen evolution reaction (HER) activity with a low overpotential (18 mV at 10 mA cm^-2), and a small Tafel slope of 43.3 mV dec^-1 in alkaline electrolyte.

Two new Ni/Co-MOFs as electrocatalysts for the oxygen evolution reaction in alkaline electrolytes

Two novel Ni/Co-MOFs electrocatalysts were synthesized. Ni-MOF demonstrated a good activity in electrocatalytic OER performances and short-term electrochemical durability.