Highly enhanced stability and efficiency for atmospheric ammonia photocatalysis by hot electrons from a graphene composite catalyst with Al2O3

Stable and cost-effective catalysts for efficient ammonia synthesis under mild conditions particularly at ambient pressure and temperature have been pursued widely and intensively. Recently we have reported a method using a composite catalyst with nano iron oxide hosted in a three-dimensional cross-linked graphene template material, Fe@3DGraphene. With this catalyst, a light driven and efficient ammonia synthesis from N-2 and H-2 directly at ambient pressure was achieved, where graphene works as an electron reservoir under light illumination. But, the catalytic activity dropped over time due to the aggregation of the Fe2O3 particles. Here we report the new version of this catalyst, a nano Al2O3 modified Fe@3DGraphene catalyst (FeeAl@3DGraphene) through a simple solvothermal method, where nano Al2O3 serves as a barrier among nano Fe2O3 to efficiently prevent the aggregation of the Fe2O3 particles. The optimized ammonia synthesis rate of 430 mu g g(cat)(-1) h(-1) was achieved and kept steady for a 60-h test which was enhanced to more than twice of the previous catalyst without Al2O3 structural promoter. (C) 2017 Elsevier Ltd. All rights reserved.