Continuously interconnected network enabled by Pt single atoms-promoted CoNiP-CoNi heterostructures for efficient water electrolysis

For the generation of renewable hydrogen via water electrolysis, it is necessary to develop electrocatalysts with high performance and maximum metal utilization. Herein, we report an effective electrocatalyst of interconnected nanonetwork based on one-dimensional CoNi@CoNiP heterostructures implanted with ultralow loading of platinum single atoms (CN@CNP-Pt). Our study indicates that the CN@CNP-Pt could promote hydrogen evolution reaction (HER) with an overpotential (η) of 22 (75) mV, while the CN@CNP counterpart requires η of 198 (291) mV for oxygen evolution reaction (OER) at 10 (100) mA cm⁻² in alkaline medium. The two-electrode electrolyzer of CN@CNP-Pt_(-)//CN@CNP₍₊₎ drives a small cell voltage of 1.49 V (1.51) at 75 °C to accomplish 10 mA cm⁻² towards freshwater (seawater) splitting, superior to the corresponding values of Pt/C_(-)//RuO₂₍₊₎ unit and other materials featured in early reports. The advantages of CN@CNP-Pt_(-)//CN@CNP₍₊₎ are also confirmed via the excellent mass activity about 15.7 times higher than that of commercial Pt/C_(–)//RuO₂₍₊₎. The CN@CNP heterostructures produces a large active surface area, multiple active sites, and excellent charge transfer. Further, implanting Pt atoms into CN@CNP surface significantly modifies the electronic structure to result in favorable free adsorption energy, thus achieving potential electrocatalysts with enhanced activity for economic and sustainable freshwater/seawater splitting.