Solvent-engineered in-situ heterogenization of copper-based sulfides for broadening electromagnetic wave absorption

Crafting multi-component heterojunctions represents an effective approach to broaden electromagnetic wave (EMW) absorption performance by boosting dielectric polarization responses. Despite various efforts to fabricate tunable multi-component configuration, the notable challenges persist in synthesis strategies and broadband absorption improvement, due to difficulties in the one-step control over precise heterogenization process. Here, a solvent-engineered heterogenization process is created, imparting a straightforward and highly effective method for fine-control construction of multi-component Cu–S–O system. Two unique states, i.e., an in-situ heterogenization or a physical phase separation, can be subtly regulated by the gradient organic/inorganic mixed solvents ratios. More importantly, the in-situ heterogenization shows a preference for establishment of “particles-on-plates” configuration characterized by abundant CuS/CuO/S heterointerfaces and sulfur vacancies, while these advantages are gradually deteriorated, even disappeared, by the physical phase separation with introducing overmuch high-polarity water. Such in-situ heterogenization configuration consequently entails strong polarization loss for optimized CuS/CuO/S composites (C3), achieving an outstanding absorption intensity of −43.05 dB, with a broad-frequency response of 7.54 GHz covering almost entire X-Ku band. This investigation underscores significance of fine-tuning heterogenization in regulating dielectric polarization behaviors to enlarge broadband absorption. The simple yet robust solvent-engineered heterogenization strategy could be conveniently leveraged to many other promising research fields beyond EMW absorption.