Single-Atom Copper Promotes Efficient Generation of Hydroxyl Radicals under Alkaline Circumstances in a Photoelectrochemical Oxygen Reduction Process

A traditional Fenton reaction suffers the limitation of acidic conditions, impeding its practical application for environmental remediation. Selective reduction of oxygen with sustainable photo-electrochemical (PEC) technology was first proposed to enlarge the practicable pH range of 7-11. A novel photoelectrode with single-atom copper anchored on oxygen vacancy anatase (Cu-SA/TiO2-x) was designed for the efficient production of hydroxyl radicals (HO & BULL;) in an alkaline solution. The in situ-formed O-Cu on the electrode surface promoted the decomposition of electrogenerated H2O2 into HO.. The optimal accumulated concentration of HO. was 276.23 mu mol &.L-1 during PEC reduction of O2 at pH = 9. The removal of sulfamethoxazole was up to 96.3% in 10 min with the Cu-SA/TiO2-x electrode with an apparent kinetic constant (k(obs)) of 0.311 min-1. The energy consumption, recycling capacity, and electrolyte effect were evaluated in detail from the perspective of actual application. Furthermore, the high removal of chemical oxygen demand (69.1-93.9%) and the efficient removal of total nitrogen (25.1-87.7%) in five real water samples were almost uninfluenced by water quality. This work not only proposed a strategy of HO. production in the alkaline environment but also provided guidance for developing sustainable and efficient technologies, especially for decentralized water treatment.

Automated summary

This study proposed a strategy of efficiently producing hydroxyl radicals in an alkaline environment using photoelectrochemical technology, and designed a novel photoelectrode for effective pollutant removal in environmental remediation. Experimental results demonstrated that this technology is highly efficient, sustainable, and universally applicable, with minimal impact on water quality.