Soft template-assisted design and synthesis of anisotropic 2D–3D CuInS2 with a controlled morphology and band gap: exploring photothermal interfacial water evaporation

Abstract

Synthesizing I–III–VI₂ ternary semiconductor chalcogenide nanostructures with precise control over their shape and bandgap is a major focus of current research. These materials are highly sought after because of their remarkable physical, chemical, and optical properties. These nanostructures hold promise for harvesting solar energy, offering potential in light-to-heat conversion. Herein, three distinct solvent/soft-template systems were employed to control the morphology and band gap of 2D–3D hierarchical CuInS₂ nanostructures. The soft template significantly influences the evolution of nanosheets and nanoflowers through oriented attachment, self-assembly, and Ostwald ripening mechanisms. The synthesized CuInS₂ exhibits a broad solar absorption range, narrow band gap, high surface area, excellent hydrophilicity, and strong localized heating properties, and achieves a remarkable evaporation rate of up to 1.55 kg m⁻² h⁻¹, and a maximum efficiency of 96% under 1 sun illumination. Additionally, the porous hierarchical interconnected sheet structure of CuInS₂ facilitates efficient salt dissolution, ensuring high salt tolerance and a stable evaporation rate while preserving structural and morphological integrity. This, combined with large-scale water production and decontamination, makes them ideal candidates for solar-driven interfacial water evaporation (SIWE) systems. Thus, this study presents an innovative strategy for developing ternary metal chalcogenides with a controlled morphology and band gap, fostering their unexplored photo-responsive properties.