Tube-Sponge-Inspired hierarchical electrocatalysts with boosted mass and electron transfer for efficient oxygen evolution.

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-sea sponges, we fabricated an exceptionally active and binder-free porous nickel tube arrays (PNTA) decorated with NiFe-Zn2+ -pore nanosheets (NiFe-PZn ). The PNTA facilitated removal of bubbles and electron transfer in 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 172 mV at 10 mA∙cm-2 (with a Tafel slope of 50 mV∙dec-1 ). Furthermore, this electrocatalytic system recorded excellent reaction stability over 360 hours with constant current density of 100 mA∙cm-2 at the potential of 1.52 V (versus RHE). This work provides a new strategy of designing hierarchical electrocatalysts for highly efficient water splitting. This article is protected by copyright. All rights reserved.