2D Nanomaterials in Flexible Fuel Cells

Abstract

The nanomaterials are classified as zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) nanomaterials. This classification is based on the size of each dimension of the material and normally the dimension that is >100 nm is only counted as a dimension of a material. Among these classes, the 2D nanomaterials are superior to all others in several properties such as high surface-to-volume ratio, porous structure, higher stability, high electrical conductivity, good mechanical strength, and flexible nature. Their surface functionalization and doping property have also widened their applications in the field of environment, medicines, textile, military, energy storage and production, sensing, etc. These 2D nanomaterials and their hybrids/composites are used in various electronic and portable devices to increase their efficiency and make them cost-effective and lightweight. Graphene, carbon nanotubes and transition metal oxides (TMOs)-based nanosheets are used in electrode materials of supercapacitors, batteries, and fuel cells. The 2D nanomaterials-based hybrid transition metals are used as high-performance electrocatalysts in electrochemical reactions such as MoS2 and WS2 in hydrogen evolution reaction for the production of environment-friendly hydrogen fuel. The 2D materials have lot of energy conversion and storage applications and made our life easier by replacing larger and heavier batteries and fuel cells with smaller, lightweight, and flexible devices comprising higher efficiency. As flexible energy devices are getting more attention due to their promising properties and increasing demand for wearable and portable electronics. However, it is yet a challenge to fabricate flexible devices exhibiting high energy density. Flexible proton exchange membrane fuel cell (PEMFC) is the only type of fuel cell that is experiencing comparable or even higher energy density as compared to traditional, bulky, and rigid PEMFC. However, more work is needed to design and fabricate the flexible fuel cell stack without compromising energy efficiency.