Interfacial Synergetic Integration of Graphitic Carbon Nitride-Polypyrrole Anchored on Carbon Nanorod for Efficient Water Electrolysis

Hydrogen generation from electrolysis of water is one of the most sustainable strategies for clean energy conversion. However, the sluggish kinetics of oxygen and hydrogen evolution limit its practical implementation. Developing an efficient, low-cost, and durable bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is always in demand for promoting clean energy from water. In this work, we report a unique metal-free electrocatalyst composed of graphitic carbon nitride-polypyrrole on carbon nanorods (g-C ₃ N ₄ -Ppy/CR) for efficient water electrocatalysis. The above electrocatalyst was synthesized by depositing g-C ₃ N ₄ -Ppy on the surface of a metal-organic framework-derived carbon nanorod (CR). The unique heterointerface of the electrocatalyst endows it with outstanding bifunctional activity, requiring overpotentials of only 355 mV and 187 mV to achieve 10 mA cm ^− 2 current density with a small Tafel slope of 86 mV dec ^− 1 and 105 mV dec ^− 1 for OER and HER, respectively. The chronoamperometric performance further confirmed the long-term stability of the electrocatalyst, with over 50 hours of continuous operation maintained. Moreover, owing to the excellent OER and HER performance in alkaline media, the overall water splitting was carried out by using a two-electrode system. A cell voltage of 1.8 V was sufficient to achieve a current density of 10 mA cm ^− 2 , which is only 0.07 V higher than the commercially available catalyst-modified cell. The g-C ₃ N ₄ -Ppy/CR-modified cell also has excellent stability at a higher current density of 3.1 mA cm ^− 2 . These results highlight the synergistic interplay between the components and provide a promising strategy for designing new ternary electrocatalysts toward efficient overall water splitting and renewable hydrogen production.