Engineering nanostructures of PGM-free oxygen-reduction catalysts using metal-organic frameworks

Abstract

Oxygen reduction reaction (ORR) is one of the essential electrochemical reactions for the energy conversion and storage devices such as fuel cells and metal-air batteries. However, a large amount of Pt is required for catalyzing the kinetically sluggish ORR at the air cathode, therefore greatly limiting their large scale implementation. Development of high-performance platinum group-metal (PGM)-free ORR catalysts has been a long-term goal for such clean energy technologies. However, current PGM-free catalysts are still significantly suffering from insufficient activity and limited durability especially in more challenging acidic media, such as proton exchange membranes (PEM) fuel cells. Recently, metal-organic frameworks (MOFs), constructed from bridging metal ions and ligands, have emerged as a new type of attractive precursors for the synthesis of PGM-free catalysts, which has led to encouraging performance improvement. Compared to other catalyst precursors, MOFs have well-defined crystal structure with tunable chemistry and contain all required elements (e.g., carbon, nitrogen, and metal). Here, we provide an account of recent innovative PGM-free catalyst design and synthesis derived from the unique MOF precursors with special emphasis on engineering nanostructure and morphology of catalysts. We aim to provide new insights into the design and synthesis of advanced PGM-free

Metal‐Organic Framework‐Derived Non‐Precious Metal Nanocatalysts for Oxygen Reduction Reaction

“…However, metals/metal oxides incorporated in these nanocatalysts vulnerable to aggregation and dissolution in practical fuel cell operation. In this case, metals with low evaporation temperature are used to synthesize MOF precursors, such as Al, Zn and Mg. [43,45,62,63] For example, Zn-containing MOFs (e.g., MOF-5, ZIF-7 and ZIF-8) have been widely used to synthesize metal-free catalysts for ORR. [61] These drawbacks can be overcome by developing metal-free nanocatalysts.…”

“…[30,[37][38][39][40] More recently, MOF-derived NPMNs are demonstrated to possess great potential in ORR electrocatalysis by serving as catalysts or supports. [45] These NPMNs with various compositions can be simply obtained by substituting the metals or organic linkers. [45] These NPMNs with various compositions can be simply obtained by substituting the metals or organic linkers.…”

Design Strategies toward Advanced MOF‐Derived Electrocatalysts for Energy‐Conversion Reactions

“…[51] In particular, as promising substitutes for noble-metal-based electrocatalysts, MOF-derived materials have been extensively investigated as alternative electrocatalysts for the ORR, OER, and HER, and have made many great achievements during the past decade. [51,52] Notably, some MOF-derived materials have shown significantly enhanced performances, even superior to noble-metal-based electrocatalysts. [51,52] A few reviews have summarized the progress of MOF-derived materials in electrocatalysis, but have mainly focused on the application of MOF-derived materials as ORR electrocatalysts in fuel cells.…”

“…[51,52] Notably, some MOF-derived materials have shown significantly enhanced performances, even superior to noble-metal-based electrocatalysts. [51,52] A few reviews have summarized the progress of MOF-derived materials in electrocatalysis, but have mainly focused on the application of MOF-derived materials as ORR electrocatalysts in fuel cells. [51,52] Regardless of recent advances in this field, the exploration of MOF-derived electrocatalysts is still in its infancy.…”

“…[51,52] A few reviews have summarized the progress of MOF-derived materials in electrocatalysis, but have mainly focused on the application of MOF-derived materials as ORR electrocatalysts in fuel cells. [51,52] Regardless of recent advances in this field, the exploration of MOF-derived electrocatalysts is still in its infancy. Accordingly, an updated perspective on the general and effective strategies toward materials design and synthesis from newly emerged MOF-derived materials has far-reaching significance, which offers valuable guidance and inspiration for further development of improved MOF-derived catalysts as well as extended applications in diverse, emerging, energy-related reactions.…”