Highly selective photo-hydroxylation of phenol using ultrathin NiFe-layered double hydroxide nanosheets under visible-light up to 550 nm

Abstract

Dihydroxybenzenes (DHB) are one of the most important fine chemicals used as raw materials or intermediates in industries. One-step selective phenol hydroxylation using a photo-Fenton system is an attractive and challenging strategy, especially under long-wavelength irradiation. Herein, we report that a highly selective photo-driven Fenton hydroxylation reaction of phenol to DHB can be achieved over NiFe-layered double hydroxide nanosheets (NiFe-NS) under visible-light irradiation with 70% phenol conversion and ∼99% DHB selectivity. A more interesting finding is that a high phenol conversion (∼40%) activity can be maintained even under monochromatic irradiation at 550 nm. The superior photocatalytic activity was attributed to the abundant defects in NiFe-NS, which facilitated the adsorption of hydrogen peroxide (H₂O₂) onto the catalyst surface and promoted the transfer efficiency of photoinduced electrons from the catalyst to H₂O₂, generating ˙OH radicals to participate in the hydroxylation of phenol.