A heterogeneous Fenton-like catalyst with single redox site has a rate-limiting step in oxidant activation, which limited its application in wastewater purification. To overcome this, a bimetallic doping strategy was designed to prepare a heterogeneous Fenton-like catalyst (Fe-Mo/rGO) with a double-reaction center. Combined with electrochemical impedance spectroscopy and density functional theory calculation, it was confirmed that the formation of an electron-rich Mo center and an electron-deficient Fe center through the constructed Fe-O-Mo and Mo-S-C bonding bridges induced a higher electron transfer capability in the Fe-Mo/rGO catalyst. The designed Fe-Mo/rGO catalyst exhibited excellent sulfamethazine (SMT) degradation efficiency in a broad pH range (4.8–8.4). The catalytic performance was hardly affected by inorganic anions (Cl⁻, SO₄²⁻ and HCO₃⁻) in the complicated and variable water environment. Compared to Fe/rGO and Mo/rGO catalysts, the SMT degradation efficiency increased by about 14.6 and 1.6 times in heterogeneous Fenton-like reaction over Fe-Mo/rGO catalyst. The electron spin resonance and radical scavenger experiments proved that ·O₂⁻/HO₂· and ¹O₂ dominate the SMT removal in the Fe-Mo/rGO/H₂O₂ system. Fe and Mo, as active centers co-supported on rGO, significantly enhanced the electron transfer between catalyst, oxidant, and pollutants, which accelerated the reactive oxygen species generation and effectively improved the SMT degradation. Our findings offer a novel perspective to enhance the performance of heterogeneous Fenton-like catalysts by accelerating the electron transfer rate in the degradation of organic pollutants.

Fe₂O₃–ZrO₂ catalysts with different morphologies (nanoplates (HZNPs), nanorods (HZNRs), nanocubes (HZNCs), and nanotubes (HZNTs)) were prepared by a hydrothermal method to investigate the effect of the morphology on the catalytic performance in the Fenton-like reaction for sulfamethazine (SMT) degradation. The Fe₂O₃–ZrO₂ catalysts were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis. The H₂O₂ adsorption and the Fe²⁺ density sites on the Fe₂O₃–ZrO₂ catalysts had a close relationship with the morphologies and exhibited an important effect on the ·OH formation in the Fenton-like reaction. Free ·OH radicals were the main oxidative species in the reaction, and the normalized ·OH concentration per surface area of the catalysts was 4.52, 2.24, 2.20, and 0.37 μmol/m² for HZNPs, HZNRs, HZNCs, and HZNTs, respectively. The Fe₂O₃–ZrO₂ catalysts with different morphologies showed good catalytic performance, and the order of SMT degradation was HZNPs > HZNRs > HZNCs > HZNTs. Total SMT removal was achieved in the Fenton-like reaction over HZNPs at pH 3.0 and 45 °C after 240 min.