Surface Hydrogen Cycling of α-Ni(OH)2 Nanosheets Promoting Catalytic Ozone Decomposition under Humid Conditions

The utilization of the catalytic ozone decomposition technique is restricted by its low activity and poor stability caused by water competitive adsorption. In this work, a unique surface hydrogen cycling mechanism of α-Ni(OH)2 is proposed that surface H atoms of α-Ni(OH)2 provide electrons to accelerate ozone decomposition and form H2O with a single oxygen atom, which is accompanied by the formation of a structure similar to NiOOH, while NiOOH can transform back into α-Ni(OH)2 under humid conditions. By introducing water into the active site cycling process through this distinctive surface hydrogen cycling mechanism, the competitive adsorption of water molecules is inhibited, thereby promoting catalytic ozone decomposition activity and stability in humid environments. Moreover, the addition of Fe boosts surface hydrogen cycling, maintaining 90% ozone removal activity for 72 h at 60% RH. Our study offers a theoretically fresh strategy of water participation in the cycling of active sites to improve the catalysts’ wet resistance.