*3.4. Free Radical Trapping Experiment*

To investigate the active species generated during RhB degradation over H-CuFeS2, the trapping experiment was conducted using NaN<sup>3</sup> and methanol (each 0.1 M) as the capturing agent for •SO<sup>4</sup> <sup>−</sup> radicals and •OH radicals, respectively. The implemented trapping experimental procedure was identical to the steps mentioned in the degradation section with an additional step of adding the capturing agent at each run.
