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 H 2 O 2 and stepped activating the as-generated H 2 O 2 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 2 reduction to H 2 O 2 intermediates and Fe sites are responsible for activation of the as-generated H 2 O 2 to · OH. The CoFe DAC delivers a higher · OH production rate of 2.4 mmol L -1 min -1 g cat -1 than the single-site catalyst Co-NC (0.8 mmol L -1 min -1 g cat -1 ) and Fe-NC (1.0 mmol L -1 min -1 g cat -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.