Hetero-atom doped graphene for marvellous hydrogen storage: unveiling recent advances and future pathways

Hydrogen energy and storage are gaining significant attention due to their potential to address various energy and environmental challenges. The storage of hydrogen in solid-state media is an area of significant interest and research in comparison to compressed gas or liquefied hydrogen storage in high-pressure and large-volume storage tanks. Solid materials can store hydrogen in a condensed form, allowing more hydrogen to be stored within a smaller volume or mass. In addition, solid-state materials offer safer hydrogen storage compared to gaseous or liquid hydrogen where hydrogen is stored at very high pressure (350-700 bar). Extensive research has been carried out on graphene-based materials doped with heteroatoms, showing promise as potential candidates for hydrogen storage. This is attributed to their distinctive properties and improved ability to adsorb hydrogen. Several heteroatoms, such as nitrogen, boron, and sulfur, have been extensively studied for their effects on graphene's hydrogen storage performance. As far as the authors know, there is no critical review reported on heteroatom-doped graphene for hydrogen storage. This article is a comprehensive review of the recent progress of various types of heteroatom (e.g., N, B, Pd, Ni, Ti, Ca, Al, Be, Li, etc.) doped graphene-based materials used for hydrogen storage. The doping level, type of heteroatom, and specific synthesis methods, which greatly influence hydrogen storage performance, are discussed in detail. Lastly, the current challenges and prospects of heteroatom-doped graphene as an effective material for hydrogen fuel cell technology are discussed. This review outlines the role of heteroatom-doped graphene in hydrogen storage. It covers storage mechanisms, critical research findings, current challenges, future research directions, and commercial implications in detail.