In-situ transformation obtained defect-rich porous hollow CuO@CoZn-LDH nanoarrays as self-supported electrode for highly efficient overall water splitting

Driving the electrochemical water splitting is considered as a green and sustainable method to produce hydrogen energy. Herein, a novel strategy to fabricate the dual-metal zeolitic imidazolate framework (CoZn-ZIF) nanocrystals on Cu(OH)(2) nanowires supported by Cu foam (CF) as a precursor to change the conventional LDH growth has been proposed. It can obtain highly ordered hollow CuO@CoZn-LDH nanoarrays with defect-rich porous surface for efficient overall water splitting. Specifically, the appropriate adjustment of Co/Zn metal ratios in the ZIF precursor could lead to a well-defined morphology to create the defect-rich porous surface, which exposes more active sites and the accessibility of electrolyte to promote the electrocatalytic efficiency. The obtained hollow CuO@CoZn-LDH/CF nanoarrays catalyst exhibits an excellent activity in alkaline media with the low overpotentials of 194 mV and 124 mV at the current density of 10 mA cm(-2) for OER and HER, respectively. Remarkably, as bifunctional electrodes for overall water splitting, it displays an alkali-electrolyzer with a low cell voltage of 1.55 V at the current density of 10 mA cm(-2), and can be comparable to commercial the IrO2@CF parallel to Pt/C@CF couple catalyst. The work provides a new prospect for the rational design and fabrication of advanced hierarchical multifunctional electrocatalysts in electrochemical energy device application.

Automated summary

A novel strategy was proposed to fabricate dual-metal zeolitic imidazolate framework (CoZn-ZIF) nanocrystals on Cu(OH)(2) nanowires, leading to the formation of highly ordered CuO@CoZn-LDH nanoarrays with defect-rich porous surface for efficient water splitting. The catalyst showed excellent activity with low overpotentials for oxygen and hydrogen evolution reactions in alkaline media, and demonstrated a low cell voltage for overall water splitting, comparable to commercial catalysts. This work provides a new perspective for designing and fabricating advanced multifunctional electrocatalysts for electrochemical energy devices.