Flame-retardant substances help prevent the formation and spread of fires in materials such as polymers. However, many of the commonly used minerals and organic compounds have toxicity and stability problems.

Liangti Qu, Beijing Institute of Technology, China, Liming Dai, Case Western Reserve University, Cleveland, OH, USA, and colleagues have developed an environmentally friendly and stable flame-retardant graphene-oxide foam. The material is easily synthesized by mixing a solution of graphene oxide with hexachlorocyclotriphosphazene (HCTP, P₃N₃Cl₆) and subsequent freeze-drying. The product was then thermally treated to give a graphene–phosphorus oxide/nitride (GPO) foam.

The resulting foam has a very low density, good compressibility, and is an efficient flame retardant. In terms of its degradation temperature, it performed better than conventional polymer, metallic oxide, and metal hydroxide based materials. Additionally, the material showed an excellent microwave absorption capacity, which could make it useful in electromagnetic interference shielding.

• Scalable Preparation of Multifunctional Fire-Retardant Ultralight Graphene Foams,
  Chuangang Hu, Jiangli Xue, Liye Dong, Yue Jiang, Xiaopeng Wang, Liangti Qu, Liming Dai,
  ACS Nano 2016.
  DOI: 10.1021/acsnano.5b06710