Importance of 2D nanomaterials for energy -- Graphene-based 2D nanomaterials for fuel cells -- MXene-based 2D (dimensional) nanomaterials for fuel cells -- 2D nanomaterials in flexible fuel cells -- Two dimensional (2D) nanomaterials for portable and flexible fuel cells -- Role of 2D materials in organic and perovskite photovoltaics -- Graphene-based 2D nanomaterials for solar cells -- Chalcogenide based 2D nanomaterials for solar cells -- Metal phosphide based 2D nanomaterials for solar cells -- MXene-based 2D nanomaterials for solar cells -- Nouveau advancements achieved in the performance enchantment of solar cells modified through MXene-based 2D nanomaterials utilization -- Nanocomposites of MXene for photovoltaic applications -- Graphene based nanomaterials for battery applications -- Chalcogenide based 2D nanomaterials for batteries -- Metal phosphide based 2D nanomaterials for batteries -- MXene-based 2D nanomaterials for batteries -- Vanadium dichalcogenides based 2D nanomaterials for batteries -- Emerging applications of 2D nanomaterials for flexible batteries -- Nanocomposites of 2D materials for flexible li-ion batteries -- Graphene-based 2D nanomaterial for supercapacitors -- MXene-based 2D nanomaterials for supercapacitors -- 2D nanomaterials for flexible supercapacitors.