Enhancing photoelectrochemical catalytic performance of zeolite-Co₃O₄ composites through optimized ball milling...

This study investigates the impact of ball milling duration on the structural, optical, and photoelectrochemical properties of zeolite-Co₃O₄ composites. Catalysts were synthesized using varying ball milling times and characterized using FESEM, FTIR, UV-Vis spectroscopy, EDX, and XRD, revealing that increased ball milling enhances Co₃O₄ dispersion within the zeolite matrix, leading to improved light absorption, reduced bandgap energy, and enhanced photocatalytic activity. Furthermore, the photoelectrochemical response of the Cat 4 photocatalyst was investigated under monochromatic light irradiation (390-636 nm) in a 0.5 M Na₂SO₃⋅5H₂O electrolyte at room temperature. The photocurrent density (J_ph) varied with wavelength, peaking at - 1.62 mA/g at 636 nm and dipping to - 1.55 mA/g at 470 nm, demonstrating significant absorption and effective use of visible light. The incident photon-to-current conversion efficiency (IPCE%) was evaluated, revealing a peak value of 4.98% at 390 nm and a minimum of 3.16% at 636 nm. The applied bias photon-to-current efficiency (ABPE%) analysis demonstrated a maximum efficiency of 0.098% at 636 nm with an applied potential of 0.56 V vs. RHE. Photoelectrochemical measurements demonstrate that the catalyst with the longest ball milling duration exhibits the highest photocurrent density and hydrogen evolution rate, confirming the catalyst's effective charge carrier separation and transport, contributing to enhanced solar-to-hydrogen energy conversion, and indicating its superior performance in PEC water splitting.