Carbon nanomaterials can have a unique place in the field of nanotechnology thanks to their exceptional electrical, optical, chemical, and mechanical properties, and thus they have become promising for a diverse array of applications. More importantly, the properties of a specific carbon nanomaterial are often determined by the structure of the material itself, which further traces back to its synthesis. Accordingly, it is of great interest and importance to understand the relationship between the synthesis, structure, and properties of the carbon nanomaterials. My thesis begins with the chemical vapor deposition (CVD) synthesis and investigation of various graphene/nanotube (NT) hybrid structures in Chapter 1, including rebar graphene from functionalized boron nitride nanotubes (BNNTs), growing carbon nanotubes (CNTs) from both sides of graphene, and the selective growth and transfer of seamless three-dimensional (3D) graphene/CNT hybrids. Then, Chapter 2 discusses the fabrication of laser-induced graphene (LIG) materials in controlled atmospheres. Next, Chapter 3 describes the 3D printed graphene foams. Finally, Chapter 4 introduces biochar as a renewable source for high-performance CO2 porous carbon sorbent.