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 [email protected] 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 [email protected]/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||Pt/[email protected] couple catalyst. The work provides a new prospect for the rational design and fabrication of advanced hierarchical multifunctional electrocatalysts in electrochemical energy device application.