A 3D rGO-supported NiFe2O4 heterostructure from sacrificial polymer-assisted exfoliation of NiFe-LDH for efficient oxygen evolution reaction

NiFe2O4 takes an attractive potential candidate for oxygen evolution reaction (OER) catalysts, however, its usual preparation based on high-temperature calcination limits exposure of catalytically active sites. Herein, we report a new and efficient strategy for preparing NiFe2O4 supported by three-dimensional graphene network (NFO/3DGN) electrocatalysts. Specifically, NiFe layered double hydroxide (NiFe LDH) was exfoliated to single layer by polylactic acid (PLA), single layer NiFe LDH was released when PLA was hydrolyzed, and PLA hydrolysate etched single layer NiFe LDH to NiFe2O4; Meanwhile, the lamellar graphene oxide was reduced to 3DGN, so that NiFe2O4 was loaded on 3DGN, which means the agglomeration of NiFe2O4 could be prevented and efficient electron transmission channels for NiFe2O4 could be provided due to 3DGN. The as-prepared NFO/3DGN-10 exhibited an excellent electrocatalytic activity and stability for OER in an alkaline solution (with a low overpotential of 272 +/- 25 mV at 10 mA cm(-2) with a Tafel slope of 64 mV dec(-1)). Based on theoretical calculations, the reaction energy barrier of NiFe2O4 on the speed determination step reduced significantly owing to 3DGN. These results indicate that this facile fabrication method is a promising route for developing high-performance catalysts based on mixed metal spinel oxides supported by 3DGN.

Automated summary

A new and efficient strategy for preparing NiFe2O4 electrocatalysts supported by a three-dimensional graphene network was reported. The NiFe2O4 was loaded on the graphene network, preventing agglomeration and providing efficient electron transmission channels. The as-prepared NFO/3DGN-10 exhibited excellent electrocatalytic activity and stability for oxygen evolution reaction in an alkaline solution.