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

Abstract 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 Fe 2 O 3 particles. Here we report the new version of this catalyst, a nano Al 2 O 3 modified Fe@3DGraphene catalyst (Fe Al@3DGraphene) through a simple solvothermal method, where nano Al 2 O 3 serves as a barrier among nano Fe 2 O 3 to efficiently prevent the aggregation of the Fe 2 O 3 particles. The optimized ammonia synthesis rate of 430 μg 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 Al 2 O 3 structural promoter.