Air plasma activation of catalytic sites within MXene nanosheets for oxygen evolution and urea oxidation catalysis

Abstract

Atmospheric pressure medium–blocked discharge plasma modified the hydroxyl and fluorine groups on the dispersed surface of MXene as well as the valence states of metal ions to promote electrocatalytic reactions efficiently. The plasma-treated samples maintain the nature and macroscopic morphology of the open active sites of the original framework structure, whereas the valence and electronic structures of the metal centers are altered. When dielectric barrier discharge plasma-modified MXene is used to assemble a monolithic hydrolysis device for hydrogen evolution reaction (HER)||oxygen evolution reaction (OER), the current density is up to 100 mA/cm2 at 2.1 V (actual data without IR compensation). Furthermore, in urea-assisted water electrolysis HER||urea oxidation reaction, the voltage is only 1.8 V, which is 300 mV lower than that of HER||OER. Meanwhile, the electrocatalytic system can operate continuously with high durability for more than 100 h. This work provides an effective electrocatalyst not only for efficient hydrogen production but also for urea wastewater purification.