Unraveling the chemistry of PVP in engineering CdS nanoflowers for sunlight-driven photocatalysis

Abstract

Photocatalysis, a light-driven process in which a nanostructured catalyst accelerates chemical reactions without getting consumed, offers an effective solution for environmental remediation. However, the synthesis of efficient visible-light-driven photocatalysts with a stable morphology remains a challenging task. In this work, we report the chemistry involved in the synthesis of a three-dimensional (3D) cadmium sulfide nanoflower (CdS NF) photocatalyst with excellent optoelectronic properties and promising natural solar-driven photocatalytic activity. CdS NFs exhibit superior light absorption owing to their unique 3D structure, enhancing their photocatalytic performance. In this study, we investigated the hydrothermal synthesis of CdS NFs using polyvinylpyrrolidone (PVP) as a capping agent with emphasis on its role in optimizing the morphology of the 3D NFs and their optoelectronic properties. The synthesized PVP-assisted CdS nanostructures were characterized using various microscopy and spectroscopic techniques, which confirmed the formation of 3D NFs with enhanced visible light absorption capability, a band gap in the range of 2.24–2.15 eV and a low electron–hole recombination rate. The solar-driven photocatalytic activity of the optimized PVP-assisted CdS NFs showed that the NFs significantly improved the photodegradation of methylene blue, achieving 93% degradation in 180 minutes. Furthermore, the photocatalytic performance of the CdS NFs was evaluated against anionic and cationic dyes as well as pharmaceutical drug pollutants, demonstrating their broad degradation capability. In addition, electrochemical impedance spectroscopy (EIS) and BET surface area analyses confirmed their improved charge transfer dynamics and high surface area, which are favorable for photocatalysis. Furthermore, the mechanism and chemistry of the role of PVP in establishing the morphology of the 3D CdS NFs with enhanced photocatalytic performance together with photostability and recyclability were discussed. This study highlights the impact of capping agents in optimizing the morphology and optical properties of CdS NFs for environmental remediation and energy applications.