A novel hierarchically hybrid structure of MXene and bi-ligand ZIF-67 based trifunctional electrocatalyst for zinc-air battery and water splitting

The development of cost-effective and durable electrocatalysts possesses a broad spectrum of applications in sustainable energy systems. Herein, a hierarchical composite of Co-based bi-ligand zeolite imidazole framework (ZIF-67) with highly conducting 2D MXene as highly efficient noble metal free electrocatalyst for electrochemical oxygen reduction reaction (ORR), complete water splitting, along with zinc-air battery (ZAB) has been studied. ZIF-67 is reported as an efficient electrocatalyst due to its porous structures, high surface area and atomically dispersed active metal centres while low conductivity and structural instability have been addressed by pyrolysis. In this work, structural disintegration due to temperature effect has been handled by using bi-ligand linkers in ZIF (b-ZIF-67) which controls its sharp morphology and uniform mesoporous structure. This b-ZIF-67 has been supported on highly conducting 2D MXene material which exposes ample accessible active sites to accelerate the electroactivity of the synthesized catalyst. The resultant b-CZIF-67/MXene catalyst exhibits superior onset of 0.91 and 0.93 V in acidic and alkaline medium respectively for ORR. At the current density of 10 mA/cm² catalyst shows a very low overpotential of 0.170 mV and 1.47 V for HER and OER, respectively. The excellent specific charge storage of 550.6 mAh/g was displayed by the homemade ZAB pouch.