Freestanding Non‐Precious Metal Electrocatalysts for Oxygen Evolution and Reduction Reactions

Abstract Carbon and transition metals have emerged as promising candidates for many energy storage and conversion devices. They facilitate charge transfer reactions whilst showing a good stability. These materials, fabricated as freestanding electrodes pose the potential of simplified electrode manufacturing procedures whilst demonstrating excellent electrocatalytic, mechanical, and structural properties, resulting from interconnected (via chemical or van der Waals force bonded) network structures. In such freestanding configuration, the lack of a binder leads to a better conductivity, ease in the manufacturing processing, and allows a lower catalyst mass loading, all of which lead to obvious benefits. This Minireview summarizes different fabrication techniques of freestanding non‐precious‐metal oxygen electrocatalysts along with their performance towards the oxygen evolution reaction (OER) and/or oxygen reduction reaction (ORR). Here, we discuss electrocatalysts produced by using freestanding substrates and those obtained through the self‐assembly of different precursors. The advantages of using freestanding versus non‐freestanding configurations are also pondered. Challenges and perspectives for freestanding electrocatalysts are presented at the end of the Minireview as a guideline for future studies in the field. This work is expected to serve as inspiration for science colleagues to develop further studies into design, processing and testing strategies of freestanding low‐cost oxygen electrocatalysts.