Enhancing the photocatalytic hydrogen production performance of CdS by introducing a co-catalyst CoTPPBr4 (7,8,17,18-tetrabromo-5,10,15,20-tetraphenylporphyrin)

Abstract

This study developed an efficient photocatalyst for hydrogen production, consisting of CdS nanorods and the CoTPPBr₄ co-catalyst. The synthesized photocatalyst was characterized using a suite of techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Additionally, transient photocurrent response and electrochemical impedance spectroscopy (EIS) were carried out to further probe the material's properties. Our findings demonstrate that the CoTPPBr₄ co-catalyst significantly enhances the photocatalytic H₂ evolution efficiency under visible light irradiation. Notably, among the tested photocatalysts, a 12.5% CoTPPBr₄/CdS composite exhibited the most superior photocatalytic performance, achieving a hydrogen production rate of 41.3 mmol g⁻¹ h⁻¹, which is 4.1 times higher than that of pristine CdS. The introduction of CoTPPBr₄ effectively facilitates charge transfer within CdS, enhances the separation efficiency of light-induced electron–hole pairs, and boosts the surface H₂-evolution kinetics. This research not only introduces a promising photocatalyst for visible light-driven hydrogen production but also provides a way for the development of highly efficient and stable CdS-based hybrid semiconductor nanocomposites suitable for diverse photocatalytic applications.