Since discovering graphene, there has been a tremendous effort for the two-dimensional (2D) nanomaterials to explore their unique planar structure, physiochemical, electrochemical features. MXenes are a large family of 2D transition metal carbides, nitrides, and carbonitrides, with similar and better overall properties than graphene. However, its electronic and electrochemical properties are hugely affected by wet chemistry synthesis and processing parameters such as stoichiometry, etchant concentration, cleaning and storing conditions. The two significant issues such as face to face stacking and self-assembly need to be overcome while making the advanced MXene heterostructure. Recently we attempted to introduce the exohedral carbon nano-onions to MXene's structure to reduce aggregation due to strong van der Waals forces. The CNOs are the fullerene family's critical members that come with exohedral pores without any internal pores, which is advantageous for electrochemical applications, viz; dye-sensitized solar cells (DSSCs), supercapacitors. We will discuss its suitability and applications of those advanced heterostructures as optically transparent DSSCs for windows applications in rooftops and building walls.