At present, TiO₂ is one of the most widely used photocatalytic materials. However, the narrow response range to light limits the photocatalytic performance. Herein, we reported a successful construction of self-doped R-WO₃/R-TiO₂/CC nanocomposites on flexible carbon cloth (CC) via electrochemical reduction to increase the oxygen vacancies (O_vs), resulting in an enhanced separation efficiency of photo-induced charge carriers. The photocurrent of R-WO₃/R-TiO₂/CC at −1.6 V (vs. SCE) was 2.6 times higher than that of WO₃/TiO₂/CC, which suggested that O_vs could improve the response to sunlight. Moreover, the photocatalytic activity of R-WO₃/TiO₂/CC was explored using methylene blue (MB). The degradation rate of MB could reach 68%, which was 1.3 times and 3.8 times higher than that of WO₃/TiO₂/CC and TiO₂/CC, respectively. Furthermore, the solution resistance and charge transfer resistance of R-WO₃/R-TiO₂/CC were obviously decreased. Therefore, the electrochemical reduction of nanomaterials enabled a promoted separation of photogenerated electron–hole pairs, leading to high photocatalytic activity.

A Yb³⁺-doped BiOI 3D nanosheet array composite was successfully fabricated through a solvothermal deposition strategy on flexible carbon cloth (CC). This composite was subsequently integrated with high-chlorine fly ash (FA) blocks to form the Yb-BiOI/CC/FA hybrid material. Comprehensive characterization was performed using multiple analytical techniques for crystalline phase identification, morphological analysis, valence state, band structure evaluation, and charge carrier separation assessment. Electrochemical measurements were conducted to evaluate the material’s electronic properties. Experimental results demonstrated superior photocatalytic performance under visible light irradiation, with the Yb-BiOI/CC/FA composite achieving 52.87% methylene blue degradation efficiency. The reaction rate constant of this modified nanomaterial was approximately 2.1 times higher than that of pristine BiOI/CC/FA. Radical trapping experiments revealed that superoxide radicals (·O₂⁻) served as the predominant oxidative species. This study presents a dual-benefit strategy for environmental remediation by simultaneously achieving sustainable waste valorization of industrial byproducts (FA) and developing high-efficiency photocatalytic materials. The successful integration of rare-earth metal modification with substrate engineering provides valuable insights for designing advanced photocatalytic systems for pollutant degradation.