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 HO and stepped activating the as-generated HO 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 O reduction to HO intermediates and Fe sites are responsible for activation of the as-generated HO to OH. The CoFe DAC delivers a higher OH production rate of 2.4 mmol L min g than the single-site catalyst Co-NC (0.8 mmol L min g) and Fe-NC (1.0 mmol L min g). 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 COD than other electrochemical technologies that reported values of 29.7∼68.0 kW h kg COD. 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.