Highly Efficient Hydroxyl Radicals Production Boosted by the Atomically Dispersed Fe and Co Sites for Heterogeneous Electro-Fenton Oxidation

The heterogeneous electro-Fenton (hetero-e-Fenton)-coupled electrocatalytic oxygen reduction reaction (ORR) is regarded as a promising strategy for ·OH production by simultaneously driving two-electron ORR toward H₂O₂ and stepped activating the as-generated H₂O₂ to ·OH. However, the high-efficiency electrogeneration of ·OH remains challengeable, as it is difficult to synchronously obtain efficient catalysis of both reaction steps above on one catalytic site. In this work, we propose a dual-atomic-site catalyst (CoFe DAC) to cooperatively catalyze ·OH electrogeneration, where the atomically dispersed Co sites are assigned to enhance O₂ reduction to H₂O₂ intermediates and Fe sites are responsible for activation of the as-generated H₂O₂ to ·OH. The CoFe DAC delivers a higher ·OH production rate of 2.4 mmol L⁻¹ min⁻¹ gcat⁻¹ than the single-site catalyst Co-NC (0.8 mmol L⁻¹ min⁻¹ gcat⁻¹) and Fe-NC (1.0 mmol L⁻¹ min⁻¹ gcat⁻¹). Significantly, the CoFe DAC hetero-e-Fenton process is demonstrated to be more energy-efficient for actual coking wastewater treatment with an energy consumption of 19.0 kWh kg⁻¹ COD⁻¹ than other electrochemical technologies that reported values of 29.7∼68.0 kW h kg⁻¹ COD⁻¹. This study shows the attractive advantages of efficiency and sustainability for ·OH electrogeneration, which should have fresh inspiration for the development of new-generation wastewater treatment technology.