MoS₂/CdS Nanocomposites for HMF Photocatalytic Conversion to DFF under Visible Light Irradiation

CdS is a popular photocatalyst and has gained widespread attention for use in photocatalytic systems that harness solar energy for chemical transformations. However, the fast recombination of photogenerated electron–hole pairs in CdS restricts its practical applicability. Because MoS 2 facilitates charge separation and boosts photocatalytic activity, it has been integrated with CdS to overcome this difficulty. In this study, CdS/MoS 2 heterostructured nanocomposites were successfully synthesized via a one-step solvothermal method with control of the MoS 2 content. The enhanced photocatalytic performance of MoS 2 /CdS nanocomposites for the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) was investigated under anaerobic conditions with visible light irradiation. The optimal MoS 2 content was determined to be 4.5%, which results in complete HMF conversion with nearly 100% selectivity toward DFF within 2 h of irradiation. In situ XPS analysis confirmed that upon photoexcitation of MoS 2 /CdS, photogenerated electrons were rapidly transferred from CdS to MoS 2, leading to hole accumulation in CdS and electron accumulation in MoS 2 and therefore facilitating efficient charge carrier separation. Thus, the MoS 2 /CdS composites exhibited significantly higher photocatalytic activity than pristine CdS, owing to the effective suppression of electron–hole recombination. This work not only deepens the understanding of photocatalytic mechanisms but also underscores the potential of MoS 2 /CdS composites in environmental and energy-related applications. These findings contribute to the advancement of photocatalytic materials science for the development of efficient and sustainable technologies for chemical synthesis and environmental remediation.