Coupling the power of spinel nanoparticles: dual-function metal ferrite catalysts for advanced piezo-photocatalytic and electrocatalytic water splitting

Abstract

Hydrogen production through green methods is essential for achieving a green and sustainable energy goal. However, the slow reaction kinetics of the oxygen evolution reaction (OER) and the instability of catalysts for the hydrogen evolution reaction (HER) pose significant challenges to optimizing various water-splitting technologies. Herein, we present a comparative study encompassing mono- and binary metal–organic frameworks (MOFs) and mono- and binary ferrites, where ferrites outperform their MOF counterparts. Both binary MOFs and ferrites exhibited better performance than their mono variants. TEM analysis revealed the nanoscale morphology and crystalline features of the prepared ferrites. At the same time, EDS and BET analysis confirmed the chemical composition, specific surface area, and pore volume, highlighting their structural and electronic properties. Additionally, we compared piezo-photocatalysis and electrocatalysis, providing insights into the smart integration of both technologies. Gas chromatography demonstrated the synergistic coupling of piezoelectricity and photon-excited reactive species in Zn_0.5Co_0.5Fe₂O₄. Remarkably, the HER under both sonication and light achieved 484 μmol g⁻¹ h⁻¹, significantly higher than 232 μmol g⁻¹ h⁻¹ and 288 μmol g⁻¹ h⁻¹ for sonication and light alone, respectively. Electrochemical tests confirmed an OER and HER overpotential of 167 and 205 mV, respectively, along with 94% and 73% retention in chronoamperometry, validating its role as a multifunctional water-splitting electrolyzer. This work highlights the potential of designing innovative composites for stable and efficient water-splitting systems such as piezo-photocatalysis and electrocatalysis.