Boosting heterogeneous Fenton reactions for degrading organic dyes via the photothermal effect under neutral conditions

Although the heterogeneous Fenton reaction has shown great promise in the remediation of refractory organic pollutants, its widespread application is still limited by the insufficient degradation performance under neutral conditions. Here, we present a photothermal-driven heterogeneous Fenton system capable of rapidly and sustainably degrading organic dyes under neutral conditions. A magnetic heterogeneous Fenton-like iron-based catalyst (MIC) was successfully constructed by loading Fe3O4 nanoparticles in hierarchically porous polydopamine (PDA) supports with excellent photothermal effect. After activating with near-infrared (NIR) irradiation, the PDA support can serve as an internal heating source to efficiently promote the iron-catalyzed decomposition efficiency of H2O2 to OH radical and the oxidation capacity of OH radical to organic pollutants. As a result, the resulting photothermal-driven heterogeneous Fenton system exhibits outstanding degradation performance for organic pollutants (e.g., methylene blue (MB) as a model pollutant) at pH 7.0. Even if the MB solution reaches an extremely high concentration of 200 mg L-1, MIC can degrade 97.7% of MB in only 6 minutes under NIR irradiation. This degradation performance is much better than its counterparts without NIR irradiation and outperforms traditional homogeneous Fenton reactions under acidic conditions. Meanwhile, the developed MIC shows excellent catalytic stability and recyclability. After 5 cycles, the regenerated MIC could still retain more than 98.8% of the original degradation efficiency. This study provides a feasible and guiding strategy for effectively improving the degradation performance of the heterogeneous Fenton system under neutral conditions via the photothermal effect, which not only can greatly expand the applicability of the heterogeneous Fenton reaction but also give some insights into how to develop the photothermal-driven heterogeneous Fenton systems activated by solar energy.