MOF-derived V-CoxP@NC nanoarchitectures for highly enhanced electrocatalytic water splitting through electronical tuning

Electrochemical Hydrogen Evolution with Metal-Organic Framework-Derived Catalysts: Strategies for d-Band Modulation by Electronic Structure Modification

The effective use of metal-organic framework (MOF)-based materials in the electrocatalytic hydrogen evolution reaction (HER) relies on the understanding of their structural and electronic properties. While the structure and morphology of MOF-derived catalysts significantly impact HER activity, tuning the d-band structure through electronic structure modulation has emerged as a key factor in optimizing catalytic performance. Techniques such as composition tuning, heteroatom doping, surface modification, and interface engineering were found to be effective methods for manipulating the electronic configuration and, in turn, modulating the d-band. This review systematically explores the design strategies for MOF-derived catalysts by focusing on electronic structure modulation. It provides a detailed discussion of the various methods - used to modulate the electronic structure. Furthermore, the review establishes the relationship between d-band tuning, Gibbs free energy, and electronic structure modulation, supported by both spectroscopic and theoretical evidences.

Co-doped NiFe carbonate hydroxide hydrate nanosheets with edge effect constructed from spent lithium-ion battery ternary cathodes for oxygen evolution reaction

The recycling of spent lithium-ion batteries (LIBs) has received increasing attention for environment and resource reclamation. Converting LIBs wastes into high-efficiency catalysts is a win-win strategy for realizing resource reclamation and addressing sustainable energy challenges. Herein, we developed a simple method to upcycle spent-LIBs cathode powder into Co-doped NiFe carbonate hydroxide hydrate (Co/NFCH-FF) as a low-cost and efficient oxygen evolution reaction (OER) electrocatalyst. The optimized Co/NFCH-FF electrode appears very competitive OER performances with low overpotentials of 201 and 249 mV at 10 and 100 mA cm-2, respectively, a small Tafel slope of 48.4 mV dec-1, and a high long-term stability. Moreover, we reveal that the existence of Co atoms leads to the formation of a crystalline/amorphous (c/a) interface at the Co/NFCH nanosheet edge, inducing the nanosheets possess a unique edge effect to enhance electric fields and accumulate hydroxide ions (OH-) at the edge during the OER process. Benefiting from edge effect, Co/NFCH-FF shows outstanding intrinsic activity. Furthermore, Co atoms as dopants stabilize the electronic structure of Co/NFCH-FF, enabling Co/NFCH-FF to exhibit excellent catalytic stability. This work provides an effective strategy for converting the end-life LIBs to high-performance multicomponent OER electrocatalysts and proposes new insights into the mechanism of enhanced catalytic activity of Co/NFCH.

Principles of Design and Synthesis of Metal Derivatives from MOFs

Materials derived from metal-organic frameworks (MOFs) have demonstrated exceptional structural variety and complexity and can be synthesized using low-cost scalable methods. Although the inherent instability and low electrical conductivity of MOFs are largely responsible for their low uptake for catalysis and energy storage, a superior alternative is MOF-derived metal-based derivatives (MDs) as these can retain the complex nanostructures of MOFs while exhibiting stability and electrical conductivities of several orders of magnitude higher. The present work comprehensively reviews MDs in terms of synthesis and their nanostructural design, including oxides, sulfides, phosphides, nitrides, carbides, transition metals, and other minor species. The focal point of the approach is the identification and rationalization of the design parameters that lead to the generation of optimal compositions, structures, nanostructures, and resultant performance parameters. The aim of this approach is to provide an inclusive platform for the strategies to design and process these materials for specific applications. This work is complemented by detailed figures that both summarize the design and processing approaches that have been reported and indicate potential trajectories for development. The work is also supported by comprehensive and up-to-date tabular coverage of the reported studies.

Development of a novel porous cobalt, phosphorus and nitrogen co-doped carbonaceous coating by phosphiding ZIF-67 grown on nitinol fiber for selective solid-phase microextraction of polycyclic aromatic hydrocarbons from water samples

The nature and fabrication of the fiber coatings with good adsorption capacity and selectivity play a decisive role in solid-phase microextraction (SPME). In this work, a facile strategy was proposed to fabricate a cobalt, phosphorus and nitrogen co-doped carbonaceous (Co-P-NC) coating on superelastic nitinol (NiTi) substrate as a binder-free fiber for SPME. In particular, direct electrochemical in situ growth of ZIF-67 crystals served as the N-containing carbon precursor and sacrificial template for subsequent controllable conversion of ZIF-67 into a novel porous Co-P-NC coating on the NiTi wire substrate via a phosphiding process in a N₂ atmosphere. The obtained NiTi wire with the Co-P-NC coating (NiTi@Co-P-NC) was employed to investigate the adsorption of some representative aromatic analytes in water samples for the first time coupling with high-performance liquid chromatography with UV detection (HPLC/UV). The results proved that the resulting fiber showed superior adsorption selectivity for polycyclic aromatic hydrocarbons (PAHs). Therefore, the key parameters were further examined for the adsorption and preconcentration of PAHs. Under the obtained conditions, linear chromatographic responses were achieved over the concentration ranges of 0.03-100 μg L^-1 with the correlation coefficients ranging from 0.9980 to 0.9991. Limits of detection (LODs) were between 0.007 and 0.149 μg L^-1 (S/N = 3). The developed SPME-HPLC/UV method was applied to selective preconcentration and sensitive determination of PAHs in water. Moreover, this fiber had good fiber preparation reproducibility and presented 120 adsorption and desorption cycles at the same time in practical SPME application.

Critical Review, Recent Updates on Zeolitic Imidazolate Framework-67 (ZIF-67) and Its Derivatives for Electrochemical Water Splitting

Design and construction of low-cost electrocatalysts with high catalytic activity and long-term stability is a challenging task in the field of catalysis. Metal-organic frameworks (MOF) are promising candidates as precursor materials in the development of highly efficient electrocatalysts for energy conversion and storage applications. This review starts with a summary of basic concepts and key evaluation parameters involved in the electrochemical water-splitting reaction. Then, different synthesis approaches reported for the cobalt-based Zeolitic imidazolate framework (ZIF-67) and its derivatives are critically reviewed. Additionally, several strategies employed to enhance the electrocatalytic activity and stability of ZIF-67-based electrocatalysts are discussed in detail. The present review provides a succinct insight into the ZIF-67 and its derivatives (oxides, hydroxides, sulfides, selenides, phosphide, nitrides, telluride, heteroatom/metal-doped carbon, noble metal-supported ZIF-67 derivatives) reported for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting applications. Finally, this review concludes with the associated challenges and the perspectives on developing the best economic, durable electrocatalytic materials.