Dual-Functional Bi ₄ V ₂ O ₁₁ /CdS/g-C ₃ N ₄ Heterostructure with Engineered Interfaces for Optimized Environmental Iodine Capture and Solar-to-Hydrogen Conversion

Efficiently capturing the radioactive iodine released during nuclear fission is critical because improper management poses severe environmental and health threats. Alongside environmental remediation, sustainable energy production is equally important. This study presents Bi4V2O11/CdS/g-C3N4 (BCG) nanocomposite, synthesized via a simple hydrothermal and deposition-precipitation method. This heterostructure shows potential for efficiently capturing iodine and photocatalytically evolving hydrogen. Adsorption experiments revealed that all nanocomposites can capture and retain iodine; the 10% BCG variant exhibited the highest affinity. The material efficiently captured 127I (a model radioactive pollutant) from cyclohexane solution, reaching a capacity of 1584.8 mg/g within 3 h. In the vapor phase, the maximum adsorption capacity is 890.12 mg/g after 22 h. After four cycles, the material still exhibits high adsorption performance, confirming its stability and reusability. Significantly, this material also addresses energy challenges as it produces H2 under visible light irradiation (λ ≥ 420 nm). The optimized 10% BCG heterostructure delivered a H2 evolution rate of 7734 μmol/g, attributed to its well-defined heterojunction that promotes charge migration and suppresses recombination. Building on this exceptional activity, the nanocomposite demonstrates both superior iodine adsorption and efficient H2 evolution, underscoring its dual functionality for environmental remediation and sustainable energy production.