Bifunctional zeolitic imidazolate framework-67 coupling with CoNiSe electrocatalyst for efficient hydrazine-assisted water splitting.

Employing hydrazine oxidation reaction (HzOR) to substitute oxygen evolution reaction (OER) has been regarded as a promising alternative to realize energy-saving hydrogen generation during water splitting. Herein, we introduce a combined experimental and theoretical investigation of zeolitic imidazolate framework-67 coupling with CoNiSe-3 (ZIF67@CoNiSe-3) as an efficient electrocatalyst towards both hydrogen evolution reaction (HER) and HzOR. The as-prepared ZIF67@CoNiSe-3 with nanoflower structure and highly porous ultrathin nanosheet arrays can endow advanced electrocatalytic properties for HER and HzOR. For instance, ZIF67@CoNiSe-3 demands a low overpotential of 49 mV to generate 10 mA·cm-2 with a small Tafel slope of 41.4 mV·dec-1 for HER, while it can also reach an ultrahigh current density of 400 mA cm-2 at 0.13 V vs reversible hydrogen electrode (RHE) with a small Tafel slope of 44.3 mV·dec-1 for HzOR. When using ZIF67@CoNiSe-3 as both cathode and anode in a two-electrode cell for overall hydrazine splitting (OHzS), it only needs an ultralow cell voltage of 0.45 V to produce 100 mA·cm-2 with a remarkable long-term stability of 30 h. Impressively, first-principles calculations (DFT) have been employed to investigate the electrocatalytic mechanisms of ZIF67@CoNi-3 for HER and HzOR. This research could provide an efficient strategy for energy-saving H2 production during water splitting by incorporating a low-cost yet high-performance bifunctional catalyst.