Designing MOF Nanoarchitectures for Electrochemical Water Splitting

Abstract

carrier with an extremely high energy density (approximately 142 MJ kg −1 ) and zero-carbon content, has been regarded as a promising clean fuel. [1,2] In this context, electrochemical water splitting, which converts electricity into storable hydrogen, is a viable and efficient solution to mitigate severe energy shortages and greenhouse gas emissions. [3] Among these strategies, hydrogen and oxygen evolution reactions, which occur on the cathode and anode, respectively, in a water electrolyzer, are considered as two critical half-reactions of the water-splitting process. [4] Theoretically, water splitting requires a thermodynamic Gibbs free energy (ΔG) of approximately 237.2 kJ mol −1 , corresponding to a standard potential (ΔE) of 1.23 V versus a reversible hydrogen electrode (RHE), which allows the thermodynamically uphill reaction to occur in the electrolyzer. [5] However, the unfavorable thermodynamics and resulting large overpotential are the main barriers to the scalable implementation of water electrolysis for hydrogen generation. [6,7] Currently, noble metal-based electrocatalysts exhibit the most efficient activity for water splitting, particularly Pt-based hydrogen evolution reaction (HER) catalysts and Ir/Ru-based oxygen evolution reaction (OER) catalysts. [8,9] Nevertheless, the scarcity and high price of precious metals severely impede their widespread use in commercial water-splitting applications. Taking these limitations into Electrochemical water splitting has attracted significant attention as a key pathway for the development of renewable energy systems. Fabricating efficient electrocatalysts for these processes is intensely desired to reduce their overpotentials and facilitate practical applications. Recently, metal-organic framework (MOF) nanoarchitectures featuring ultrahigh surface areas, tunable nanostructures, and excellent porosities have emerged as promising materials for the development of highly active catalysts for electrochemical water splitting. Herein, the most pivotal advances in recent research on engineering MOF nanoarchitectures for efficient electrochemical water splitting are presented. First, the design of catalytic centers for MOF-based/derived electrocatalysts is summarized and compared from the aspects of chemical composition optimization and structural functionalization at the atomic and molecular levels. Subsequently, the fast-growing breakthroughs in catalytic activities, identification of highly active sites, and fundamental mechanisms are thoroughly discussed. Finally, a comprehensive commentary on the current primary challenges and future perspectives in water splitting and its commercialization for hydrogen production is provided. Hereby, new insights into the synthetic principles and electrocatalysis for designing MOF nanoarchitectures for the practical utilization of water splitting are offered, thus further promoting their future prosperity for a wide range of applications.

A Review of Transition Metal Oxygen-Evolving Catalysts Decorated by Cerium-Based Materials: Current Status and Future Prospects

“…2 Electrochemical water splitting to produce H 2 is considered as one of the simplest hydrogen production methods. [3][4][5][6] However, large-scale production of H 2 by this means is greatly hindered by the sluggish kinetics of the oxygen evolution reaction OOH. 7 The high energy barrier is the direct cause of high onset potential, high overpotential, and the resulting slow kinetics.…”

Biocatalytic and Antioxidant Nanostructures for ROS Scavenging and Biotherapeutics

“…MOF, a newly developing area of porous materials, consists of organic linkers and metal‐containing nodes. Due to their high drug‐loading ability, biodegrade ability, structure/composition tunability, and regulated sizes/ shapes, MOFs and MOFs‐based materials have been widely investigated not only for basic interests, such as energy transfer and catalytic intermediate trapping, [ 125–127 ] but also for applications in biomedicine. [ 38–40,128 ] To our knowledge, recent studies have correlated with Mn‐based MOFs for specific and effective antioxidant applications.…”

Electronic Modulation Caused by Interfacial Ni‐O‐M (M=Ru, Ir, Pd) Bonding for Accelerating Hydrogen Evolution Kinetics

“…In this regard, metal-organic frameworks (MOFs), as a kind of ideal catalyst support, have the advantages of periodic porous structure, rich active sites, and accessible transport pathways, which can realize the precise manipulation of the components and dispersion states of catalysts. [26,27] Moreover, MOFs can significantly adjust the chemical microenvironment around guest metal NPs compared to traditional catalyst supports through exposed Lewis acid or base sites, thereby improving catalytic activity. [28] More importantly, MOFs feature high capability for cleaving the H-OH bond, and they can act as the co-catalysts to couple with other electrocatalysts for boosting the HER kinetics in alkaline or neutral media.…”