Metal–organic framework and carbon hybrid nanostructures: Fabrication strategies and electrocatalytic application for the water splitting and oxygen reduction reaction

Abstract

With the rapid development of economy, the increasing energy crisis and environmental pollution urge us to develop sustainable and clean novel energy systems. Among them, the electrochemical energy conversion technology is considered as one of the ideal potential alternative energy systems, and the electrocatalysts play critical roles but are still challenging. Metal-organic frameworks (MOFs), thanks to their regular channels, atomically dispersed active centers, adjustable chemical and pore environments, have severed as promising electrocatalysts for electrochemical energy conversion. However, the relatively low conductivities and instabilities of MOFs limit their wide application in this field. In this case, fabricating hybrids of MOFs and carbon-based materials is an effective way to overcome above deficiencies. In addition, the synergistic effects between MOFs and carbons could optimize the electronic structures of active sites and promote the active surface areas, and thus improve the electrocatalytic performances of the composites. Herein, we outline the current development of MOF/carbon composites, including the fabrication methods of MOFs hybridized with various dimensions of carbon-based materials and the electrocatalysis utilization for water splitting, including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). Finally, the advantages and challenges of such catalysts are highlighted and future endeavors on the development of MOF/carbon composites for the HER, OER and ORR are discussed.

Recent advances in two-dimensional nanomaterials as bifunctional electrocatalysts for full water splitting

“…A metal–organic framework is a kind of organic–inorganic hybrid material with intramolecular pores formed by self-assembly of metal ions or clusters and organic ligands through coordination bonds. 50 In layered MOFs, there are strong in-plane coordination bonds, but weak interactions between layers ( e.g. , van der Waals forces and hydrogen bonding) as shown in Fig.…”

Non‐precious Metal Catalysts for Two‐Electron Oxygen Reduction Reaction

“…reported a pore size control ranging from 20~800 nm through different acidities of the secondary ligands having bonding ability to metal nodes [101] . The intrinsic vulnerability of electrical conductivity of MOFs can be overcome by changing metal nodes and ligands as well for their applications as electrocatalysts [102] . For example, replacing Mn 2+ by Fe 2+ shows magnificent increase (million‐fold) in electrical conductivity and modification of O with S shows further enhancements in electrical conductivity [103] …”

Design Principles of Single‐Atom Catalysts for Oxygen Evolution Reaction: From Targeted Structures to Active Sites

“…Over the past few decades, researchers in this field have developed a variety of catalysts for OER, including carbonbased materials, [8][9][10][11] metal hydroxides, [12][13][14][15] phosphides, [16][17][18][19] sulfides, [20][21][22][23] and metal oxides. [24][25][26][27] At the moment, precious metal iridium-based oxides [28][29][30][31][32] and ruthenium-based oxides [33][34][35][36] are the best-performing commercial catalysts for OER, however, the limited storage and high price dictate the scope of use.…”