A Highly Efficient and Durable Water Splitting System: Platinum Sub-Nanoclusters Functionalized Nickel Iron Layered Double Hydroxides as the Cathode and Hierarchical Nickel Iron Selenides as the Anode

摘要： Developing cost-efficient and effective catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a great challenge for the applications of high-efficiency water electrolyzers. In this work, we design a highly efficient and durable water splitting system in an alkaline solution, of which the platinum (Pt) sub-nanoclusters (average size: 0.59 nm) functionalized nickel iron layered double hydroxide nanosheets on carbon fiber cloth (Pt-NiFe LDH/CC) serve as the cathode and the hierarchical (Ni0.77Fe0.23)Se2 nanosheets on CC ((Ni0.77Fe0.23)Se2/CC) act as the anode. For the HER, the three-dimensional (3D) Pt-NiFe LDH/CC electrode with an ultralow Pt content (1.56 wt%) drives a current density of 10 mA cm-2 under an ultralow overpotential of 28 mV. For the OER, the edge-rich (Ni0.77Fe0.23)Se2/CC electrode displays a current density of 10 mA cm?2 under a small overpotential of 228 mV, and the Tafel slope is as low as 69 mV dec?1. More importantly, the assembled Pt-NiFe LDH/CC || (Ni0.77Fe0.23)Se2/CC water splitting electrolyzer exhibits a high current density of 30 mA cm?2 at a low cell voltage of 1.57 V, which is superior than that of electrolyzer assembled by the commercial 20 wt% Pt/C and RuO2 electrodes (30 mA cm?2 at 1.62 V). Additionally, the Pt-NiFe LDH/CC || (Ni0.77Fe0.23)Se2/CC electrolyzer displays excellent stability over 40 hours even at a high current density of 50 mA cm?2, which shows a great potential in the practical applications of full water splitting.