Tube-Sponge-Inspired Hierarchical Electrocatalysts with Boosted Mass and Electron Transfer for Efficient Oxygen Evolution.

Abstract

Hindered gas bubble release and limited electron conducting process represent the major bottlenecks for large-scale electrochemical water splitting. Both the desorption of bubbles and continuous electron transport are achievable on the surfaces of biomimetic catalytic materials by designing multiscale structural hierarchy. Inspired by the tubular structures of the deep-seasponges, an exceptionally active and binder-free porous nickel tube arrays (PNTA) decorated with NiFe-Zn2+ -pore nanosheets (NiFe-PZn ) are fabricated. The PNTA facilitate removal of bubbles and electron transfer in the oxygen evolution reaction by reproducing trunks of the sponges, and simultaneously, the NiFe-PZn increase the number of catalytic active sites by simulating the sponge epidermis. With improved external mass transfer and interior electron transfer, the hierarchical NiFe-PZn @PNTA electrode exhibits superior oxygen evolution reaction performance with an overpotential of 172mV at 10mAcm-2 (with a Tafel slope of 50mVdec-1 ). Furthermore, this electrocatalytic system recorded excellent reaction stability over 360h with a constant current density of 100mAcm-2 at the potential of 1.52V (versus RHE). This work provides a new strategy of designing hierarchical electrocatalysts for highly efficient water splitting.