Hot electron prompted highly efficient photocatalysis based on 3D graphene/non-precious metal nanoparticles

High dispersibility and rapid electron transfer are required for a highly efficient catalyst. In this work, such materials have been designed using a scalable hydrothermal method from graphene oxide and a metal-organic framework. A cross-linked three-dimensional graphene (3DGraphene) material loaded with mono-dispersed nitrogen-doped carbon-coated metallic Co (NC@Co) nanoparticles with uniform size of 12.2 nm (3DGraphene/NC@Co) has been obtained and exhibits excellent activity for catalytic reduction of 4-nitrophenol to 4-aminophenol. Such high catalytic activity can be assigned to the highly energetic hot/free electrons arising from 3DGraphene under light illumination and the synergistic effect between 3DGraphene and NC@Co nanoparticles. The catalytic reaction can be finished in 240 s with NaBH₄ as the reducing agent, and the corresponding rate constant (k) is 1.5 × 10^-2 s^-1, comparable to that of reported noble metal catalysts. Furthermore, the magnetic 3DGraphene/NC@Co materials are beneficial for the separation from the mixture after reaction and exhibit excellent cycling stability.