Constructing self-standing Fe ₂ O ₃ -Pt/NF nanoflowers with synergistic active sites for efficient electrocatalytic overall (sea) water splitting

Designing cost-effective and highly stable heterostructures with synergistic active sites could simultaneously catalyze the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) for (sea) water splitting. However, there are still challenges in maintaining the catalytic performance of individual materials and in constructing intimate interfaces. Herein, a novel corrosion engineering method is provided to prepare self-standing Fe₂O₃-Pt/NF nanoflowers where ultra-small amounts of Pt combined with Fe₂O₃ are in situ grown on nickel foam (NF) in the corrosion system of "H₂PtCl₆-NaCl-FeCl₃". The synthesized Fe₂O₃-Pt/NF shows the presence of a Pt-O bond, which can regulate the electronic structure of the active sites and optimize the binding energy of the reaction intermediates, leading to an improvement in catalytic performance. Compared with Pt/NF and FeOOH/NF, the Fe₂O₃-Pt/NF heterostructure exhibits remarkable electrocatalytic activities with overpotentials reaching 94 mV and 265 mV for the HER and OER, respectively, at a high current density of 100 mA cm^-2 in alkaline solution. Furthermore, the self-assembled electrolytic cell employing Fe₂O₃-Pt/NF as the bifunctional electrode only requires potentials of 1.60 V and 1.61 V to achieve a current density of 100 mA cm^-2 in overall water and seawater splitting, respectively. This material remained stable for 10 hours without obvious attenuation, indicating its good environmental adaptability and stability. Specifically, the enhanced catalytic activity and stability can be ascribed to the abundant active sites of nanoflowers, fast electron transfer rate of intimate interfaces, and strong electronic interaction between Pt atoms and Fe₂O₃. This work provides a new insight into the construction of highly efficient co-catalysts with intimate interfaces based on corrosion engineering methods.