Graphene, 2D atomic-layer of sp2 carbon, has attracted a great deal of interest for use in solar cells, LEDs, electronic skin, touchscreens, energy storage devices, and microelectronics. This is due to excellent properties of graphene, such as a high theoretical surface area, electrical conductivity, and mechanical strength. The fundamental structure of graphene is also manipulatable, allowing for the formation of an even more extraordinary material, porous graphene. Porous graphene structures can be categorized as microporous, mesoporous, or macroporous depending on the pore size, all with their own unique advantages. These characteristics of graphene, which are further explained in this paper, may be the key to greatly improving a wide range of applications in energy storage systems.

Porous graphene possesses great potential as an anode material for sodium-ion batteries. Due to the porosity of the graphene, the increase in surface area allows for shorter diffusion length for electrolyte ions. Herein, the porous graphene oxide is created using the breath figure method, and then reduced by chemical, electrochemical, or thermal means. Sodium storage performance of the devised porous graphene is investigated and compared. Reduced graphene oxide shows altered hierarchical porous structures, which are highly dependent on reduction method and conditions. Of the three reduction methods, thermal reduction shows a superior sodium storage performance, yielding a maximum discharge capacity of 187[Formula: see text]mAh/g and charge capacity of 63[Formula: see text]mAh/g at a current rate of 50[Formula: see text]mA/g.