Ir nanoparticles anchored on nickel metal-organic framework for efficient hydrogen and oxygen evolution

To develop a low cost and high-efficiency electrocatalyst is important for the preparation of high-purity hydrogen. Herein, a series of Ir@Ni-MOF-x/NF materials (x = 0.06, 0.08, 0.09, 0.10) were obtained by anchoring iridium (Ir) nanoparticles on nickel metal-organic framework via in-situ growth on nickel foam (NF). Compared with Ni-MOF/NF, Ir@Ni-MOF-x/NF electrodes exhibit preferable hydrogen/oxygen evolution reaction (HER/OER) performance in alkaline solution. Among them, Ir@Ni-MOF-0.08/NF electrocatalyst with the optimal Ir content of similar to 1.65 wt% exhibits the most excellent HER and OER activities. For HER, it exhibits a low overpotential (eta(100) =105 mV) with a small Tafel slope (21.95 mV dec(- 1)). For OER, its overpotential is 293 mV at 100 mA cm(-2) with a Tafel slope of 62.27 mV dec(- 1). The overpotentials are significant superior compared with the traditional Pt/C (eta(100) = 218 mV for HER) and RuO2 (eta(100) = 317 mV for OER). Moreover, Ir@Ni-MOF-0.08/ NF||Ir@Ni-MOF-0.08/NF couple electrode can operate at 50 mA cm(-2) with 1.666 V keeping 32 h, which is more excellent than the commercial RuO2-Pt/C-based electrolyser. This result indicates that the introduction of Ir nanoparticles in Ni-MOF can effectively improve the catalytic activity and the Ir@Ni-MOF-0.08/NF is a potential bifunctional electrocatalyst for HER and OER.