Light-switchable catalytic activity of Cu for oxygen reduction reaction

The surface reactivity of metals is fundamentally dependent on the local electronic structure generally tailored by atomic compositions and configurations during the synthesis. Herein, we demonstrate that Cu, which is inert for oxygen reduction reaction (ORR) due to the fully occupied d-orbital, could be activated by applying a visible-light irradiation at ambient temperature. The ORR current is increased to 3.3 times higher in the potential range between −0.1 and 0.4 V under the light of 400 mW·cm−2, and the activity enhancement is proportional to the light intensity. Together with the help of the first-principle calculation, the remarkably enhanced electrocatalytic activity is expected to stem mainly from the decreased metal-adsorbate binding by photoexcitation. This finding provides an additional degree of freedom for controlling and manipulating the surface reactivity of metal catalysts besides materials strategy.