Comment on "On the origin of multihole oxygen evolution in haematite photoanodes"

The Article1 deals with the mechanism of oxygen evolution reaction (OER) on hematite photoanodes. The authors claimed that the OER rate or photocurrent density has a third-order (or power law) dependence on surface hole density. On grounds of this argument, they proposed a mechanism of multihole oxygen evolution and argued that the observed power law results from that the activation energy of key O-O bond formation step is weakly dependent on the surface hole coverage. We argue that the reaction order is one and the activation energy is inversely proportional to surface hole density. This debate may be beneficial to elucidate the actual mechanism of water photooxidation on the photoanode.