Metal-organic framework derived carbon-based electrocatalysis for hydrogen evolution reactions: A review

Metal-organic frameworks (MOFs) are highly porous structures that are made up of metal ions/cluster and organic ligands. Its large surface area and tuneable pore size make it efficient for the storage of clean energy, particularly hydrogen gas. Synthetic methods of MOF have been developed over the years by either doping with nanoparticles or noble metals. They are also employed in polymers, carbons, ionic liquids as well as solid inorganic compounds to increase the efficiency of MOFs as an energy storage unit. However, its poor conductivity and low stability are one of the limitations that can hinder potential applications. This is why hybrid MOFs-carbon are proposed to overcome such limitations. Carbon with its extensive and conductive matrix can act as a template for MOF to further enhance hydrogen and other gas storage capacities, electrocatalysis, and energy storage and conversion. This review mainly focuses on a metal-organic framework derived from carbon as a precursor to increase hydrogen evolution reaction (HER) and water splitting with its advanced features of large surface area and exposed active sites. We briefly discuss the relationship between the designs and the HER activity, morphology, characterization, and synthetic methods. Last but not least, the challenges and limitations are also mentioned in this article. One of the major problems for electrochemical water splitting is that it requires a high overpotential and is constricted by oxygen evolution reaction (OER) and HER occurring at the same time. It is difficult to obtain a highly functioning catalyst that is low in cost and stable. In spite of many achievements, metal-organic framework-derived carbon composites are seen as an excellent bifunctional catalyst for overall water splitting when doped with other inexpensive metals or nanoparticles in harsh alkaline/acid conditions.