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, an exceptionally active and binder-free porous nickel tube arrays (PNTA) decorated with NiFe-Zn2+-pore nanosheets (NiFe-P-Zn) 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-P-Zn increase the number of catalytic active sites by simulating the sponge epidermis. With improved external mass transfer and interior electron transfer, the hierarchical NiFe-P-Zn@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 h with a 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.

Automated summary

Hindered gas bubble release and limited electron conducting process are major challenges for large-scale electrochemical water splitting. In this study, biomimetic catalytic materials with multiscale structural hierarchy were designed to address these issues. The fabricated porous nickel tube arrays decorated with NiFe-Zn2+-pore nanosheets showed improved bubble removal and electron transfer, leading to superior oxygen evolution reaction performance. This work provides a new strategy of designing hierarchical electrocatalysts for highly efficient water splitting.