There is no denying that the world is heading towards an era powered by green energy resources. The need for highly efficient devices for sustainable energy storage and utilization is vital in transitioning towards the full-time realization of renewable energy for our society. In the last four decades, there have been groundbreaking developments in the large-scale commercialization of Li-ion batteries, electric vehicles, and solar power, all made possible by an in-depth understanding of the science of materials. Theoretically, there exists no problem in the production of green hydrogen, as oxides of Ir, Rh, and Pt, and the elements themselves, are excellent catalysts for the electrochemical hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with fast kinetics. Thus, more work remains to be done in the area of green energy material technology. The problem lies with the critical availability and cost of these materials, which is the underlying motivation for finding alternative energy materials and technologies. This energy transition era presents us with an opportunity to expand our horizons and knowledge in chemical engineering, materials science, and allied fields through two-dimensional (2D) nanomaterials. These materials exhibit intriguing characteristics in contrast to their bulk counterparts, coupled with interchangeable electronic properties depending on the synthesis methodologies employed. The chapter begins by introducing the family of graphene nanosheets and expands into a discussion of advanced 2D families, such as transition metal dichalcogenides (TMDs), MXenes, transition metal oxides (TMOs), and hexagonal boron nitride (h-BN).