Boosting hydrogen production of uniform CuCo-ZIF nanododecahedrons by bimetal node and glycerol

Abstract

Compared with fossil fuels reforming to hydrogen, electrolytic water to hydrogen is highly energy-intensive. It is still a big challenge to decrease the cost of electrolytic water to hydrogen. Herein, we investigate the electrocatalytic activity of uniform bimetal zeolite imidazole framework (CuxCoy-ZIFs, x: y = 1:3, 1:1, 3:1 mol ratio) nanododecahedrons. Bimetal CuxCoy-ZIFs show an obviously higher oxygen evolution reaction (OER) activity than ZIF-67, which is mainly attributed to the synergistic effect of Co and Cu. The Cu doping accelerates electron transfer and optimizes the electron structure of Co. In addition, the in-situ generated hydroxides/oxides (Co(OH)2, Cu(OH)2 Co3O4, Cu2O) during electrocatalytic reaction may be the main active sites are for ZIF-67 and CuxCoy-ZIF. Meanwhile, density functional theory calculations demonstrate that H+ and OH− adsorptions on Cu1Co1-ZIF are more favorable thermodynamically than that on ZIF-67. Furthermore, when OER is substituted by glycerol oxidation reaction (GOR), the anodic GOR current increases by 8.9 times than OER current. Compared with OER-based electrolyzer, the cell voltage of GOR-based electrolyzer has decreased by 18.81%, and its Faradaic efficiency rises to 94.4%. The innovative system can efficiently produce hydrogen at an ultra-low electric energy consumption and a high conversion of energy.