Hydrogen Peroxide Assisted Electrooxidation of Benzene to Phenol over Bifunctional Ni–(O–C ₂ ) ₄ Sites

Direct electrocatalytic oxidation of benzene has been regarded as a promising approach for achieving high-value phenol product, but remaining a huge challenge. Here an oxygen-coordinated nickel single-atom catalyst (Ni-O-C) is reported with bifunctional electrocatalytic activities toward the two-electron oxygen reduction reaction (2e(-) ORR) to H2O2 and H2O2-assisted benzene oxidation to phenol. The Ni-(O-C-2)(4) sites in Ni-O-C ar proven to be the catalytic active centers for bifunctional 2e(-) ORR and H2O2-assisted benzene oxidation processes. As a result, Ni-O-C can afford a benzene conversion as high as 96.4 +/- 3.6% with a phenol selectivity of 100% and a Faradaic efficiency (FE) of 80.2 +/- 3.2% with the help of H2O2 in 0.1 m KOH electrolyte at 1.5 V (vs RHE). A proof of concept experiment with Ni-O-C concurrently as cathode and anode in a single electrochemical cell demonstrates a benzene conversion of 33.4 +/- 2.2% with a phenol selectivity of 100% and a FE of 44.8 +/- 3.0% at 10 mA cm(-2).