Supercapacitors can be charged and discharged a lot faster than rechargeable batteries, but can usually store less energy. These properties make them particularly useful for applications that need fast charge/discharge cycles. Graphene-based materials with “holes”, i.e., nanoscale pores, can be used as supercapacitor electrodes. However, their synthesis often requires toxic oxidants and additional treatment steps.

Yongxiao Bai, Lanzhou University, China, and colleagues have developed an etching process for the production of holey graphene oxide (GO) that uses ozone and UV light. The team prepared a suspension of GO in water using ultrasound and then fed ozone through the solution under UV light. The ozone absorbs UV light and generates hydroxyl radicals, which attack the GO and create nanopores. The researchers were able to control the size of the pores by varying the reaction times.

The prepared holey GO was reduced using a hydrazine solution. The resulting films were used as supercapacitor electrodes and show a high specific capacitance of 224 F/g at a current density of 1 A/g. According to the team, the method is scalable and could be useful for the production of energy storage devices.

• Facile synthesis of reduced holey graphene oxide for supercapacitors,
  Xinjun Hu, Dongchen Bai, Yiqi Wu, Songbo Chen, Yu Ma, Yue Lu, Yuanzhi Chao, Yongxiao Bai,
  Chem. Commun. 2017.
  DOI: 10.1039/c7cc07475a