Comparative insights into CuS and Bi2S3-based heterostructured photocatalysts: advanced strategies for synthesis, characterization and enhanced photocatalytic performance evaluation

The increasing demand for clean energy and effective environmental remediation has driven the exploration of visible-light-responsive photocatalysts. Among them, copper sulfide (CuS) and bismuth sulfide (Bi2S3)-based heterostructures have emerged as promising candidates due to their appropriate band gaps, high charge carrier mobility, and excellent stability under visible light. However, the diversity of heterojunction configurations and synthesis techniques has led to scattered and inconsistent findings. This review addresses this gap by systematically analyzing the preparation methods, structural and optical characterization techniques, and photocatalytic mechanisms of CuS and Bi2S3 heterostructures. Special emphasis is placed on their role in enhancing charge separation, improving visible light absorption, and boosting photocatalytic performance in pollutant degradation, hydrogen production, and antimicrobial applications. By comparing binary, ternary, and quaternary systems, this review aims to provide a comprehensive understanding of current advancements, challenges, and future directions, thereby guiding researchers toward the rational design of next-generation photocatalysts.