Implementation of heteroatom-doped nanomaterial/core–shell nanostructure based electrocatalysts for fuel cells and metal-ion/air/sulfur batteries

Abstract

Core–shell nanostructures (CSNs) have been extensively used in energy conversion and storage (ECS) applications. CSNs feature abundant active sites and large surface areas. In addition, their size, shape, and morphology can be tailored to be uniform and controlled. The catalytic activity and performance of CSNs can be significantly improved by heteroatom doping to CSNs, which makes them even more advantageous for ECS applications. In addition to various noble metals, transition metals have been used in the cores and shells of nanostructures featuring heteroatoms. Such materials are inexpensive and exhibit excellent catalytic activity and stability. Likewise, heteroatom-doped nanomaterial and core–shell nanostructure (HCSN) based electrocatalysts serve as bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) as well as the ORR and oxygen evolution reaction (OER). These bifunctional electrodes are highly suitable for fuel cell and battery applications. In this review article, we exclusively focus on the important role of HCSNs in various types of fuel cells and batteries. In particular, we discuss the important roles and applications of HCSNs in proton exchange membranes (PEMs), anion exchange membranes (AEMs), direct methanol, microbial, and other types of fuel cells as well as metal ion batteries such as lithium (Li), sodium (Na), and potassium (K)-ion batteries. The applications of HCSNs in Li–sulfur (S) batteries and metal–air batteries, such as Li, zinc (Zn), and Na–air batteries, have also been addressed. Finally, we have discussed the technical advancements related to the applications of HCSNs in fuel cells and batteries along with their disadvantages, scope, and future prospects. This review will benefit researchers working in the ECS field as well as those investigating various other applications, such as drug delivery, sensors, and adsorption.