Hypothermia-controlled Co-precipitation route to deposit well-dispersed β-Bi2O3 nanospheres on polymorphic graphene flakes

• Stable and mono-dispersed β-Bi2O3 deposited on graphene assisted with PAA and Gel.
• Concentrated RhB can be photodegraded within 20 min by GR/Bi2O3.
• Nanoscale β-Bi2O3 spheres coated in graphene shelf with hypothermia treatment.
• Polymorphic GR flakes gained by self-assembly of PAA-Gel with temperature change.

A versatile and batch-fabrication approach was developed to deposit the mono-dispersed and stable beta-bismuth oxide (β-Bi2O3) nanospheres on graphene sheets by electrolyte-assisted co-precipitation method appended with a hypothermia step. The scanning electron microscope (SEM) results showed that well-distributed β-Bi2O3 nanospheres with an average size of about 20 nm were uniformly loaded on polymorphic graphene including porous, multilayered, platy and frizzy 3D structures. Activity of Bi2O3 nanospheres promoted nearly by a factor of two by graphene for RhB was discovered and the reliable stability of β-Bi2O3 was verified in further test. The homogeneity of Bi2O3 nanospheres on graphene was mainly attributed to slow nucleation under 4 °C and the help of organic electrolyte. The excellent activity of GR/β-Bi2O3 depended on graphene for its special electric structure and conduct ability.