**Abstract**

In recent years, a great deal of concentration has addressed the electronic and morphological characteristics of carbonaceous substances. Nowadays, particularly, graphene is one of the most popular materials in condensed-matter physics and materials science. It is used in different fields such as desalination of seawater, smartphones, computers, satellites, planes, cars, building materials, obtaining protective coatings and rust-free cars, nuclear clean up, transistors, sensors, electron microscopy, Li ion batteries, super capacitors, and bionics. Mechanical cleaving (exfoliation), chemical exfoliation, chemical synthesis, and thermal chemical vapor deposition (CVD) synthesis are the most commonly used methods today. Some other techniques are also reported such as unzipping nanotube and microwave synthesis. In graphene synthesis, starting material is usually graphite. On the other hand, different starting materials such as rice husks, fenugreek seeds, hibiscus flower petals, camphor, alfalfa plants, petroleum asphalt are used as a carbon source for graphene synthesis. In this study, alternative methods for graphene synthesis specially microwave irradiation and ultrasound energy were studied, and the performances of the final products were compared with the help of different characterization techniques. Advantages and drawbacks of these methods were clearly discussed for enhancing the understanding of the graphene synthesis phenomena.

**Keywords:** graphene synthesis, graphene characterization, microwave irradiation, ultrasound energy
