Ferroelectric modulation of CuCo₂O₄ nanorods for controllable alkaline water electrolysis

As a technology for emerging environmental applications, water electrolysis is a significant approach for producing clean hydrogen energy. In this work, we used an efficacious piezoelectric method to significantly improve the catalytic water splitting activity without affecting the morphology as well as the components by altering the bulk charge separation state inside the material. The obtained CuCo₂O₄ nanorods were treated under a corona polarization apparatus, which significantly enhanced ferroelectricity relative to that before the polarization increasing the physical charge separation and piezoelectric potential energy, enhancing the green hydrogen production. The polarized CuCo₂O₄ nanorods exhibit excellent water electrolysis performance under alkaline conditions, with hydrogen evolution overpotential of 78.7 mV and oxygen evolution overpotential of 299 mV at 10 mA cm^-2, which is much better than that of unpolarized CuCo₂O₄ nanorods. Moreover, the Tafel slopes of polarized CuCo₂O₄ nanorods are 86.9 mV dec^-1 in the HER process and 73.1 mV dec^-1 in the OER process, which are much lower than commercial catalysts of Pt/C (88.0 mV dec^-1 for HER) or RuO₂ (78.5 mV dec^-1 for OER), proving faster kinetic on polarized CuCo₂O₄ nanorods due to their higher electroconductibility and intrinsic activity. In particular, polarized CuCo₂O₄ nanorods are identified as promising catalysts for water electrolysis with robust stability, offering outstanding catalytic performance and excellent energy efficiency.