Morphology-performance relationship in hollow-sphere cobalt sulfide photocatalysts for solar-light-driven dye degradation: Integration of RSM, DFT, and machine learning

Abstract

Given the severe toxic effects of cationic dyes on various ecosystems, the removal of these pollutants from water is a globally critical environmental issue. Moreover, the morphology-tailored synthesis of novel materials plays a crucial role in effectively removing cationic dyes. In this study, an efficient hollow-sphere cobalt sulfide (CoS) photocatalyst was synthesized using a structure-tailored approach to degrade targeted dyes, such as methylene blue (MB), crystal violet (CV), rhodamine B (RB), and rhodamine 6 G (R6G), under simulated solar radiation. The controlling-synthesized CoS photocatalyst offered notable removal performance of 98.7, 93, 76, and 84.5 % for MB, CV, RB, and R6G, respectively, at neutral pH conditions. The void-sphere design substantially boosted photocatalytic degradation (PCD) performance by supplying an expansive surface area and aiding effective light capture, contributing to augmented contaminant eradication. Surface response analysis and artificial intelligence modelling were harnessed to refine dye-breakdown parameters, determining that pH, catalyst quantity, and light exposure time optimize dye degradation performance. The research outcomes established that charge-based interactions and OH^• production powered the dye-decomposition process. Mechanisms behind enhancing PCD performance were investigated via quantum mechanical analysis and non-covalent interaction studies. Additionally, the cavited-sphere-like CoS catalyst presented outstanding recyclability, and structural durability features even after three degradation cycles. In conclusion, the cavity-sphere CoS catalyst's high performance, affordability, rapid synthesis, and eco-friendliness features make it a promising option for large-scale environmental cleanup efforts.