During the current grant period, we completed projects designed to understand the surface chemistry of polar oxides. We showed how oxide dipoles change bare and supported-metal chemistry, imparting charge to switchable nanocatalysts. We showed how changing gaseous conditions above oxides can change the bulk and surface structure, controlling surface chemistry. We also investigated how doping oxides changes their catalytic and light absorption properties. We demonstrated that metal cations can be incorporated accompanied by vacancies, leading to recycling of catalytic metals as intelligent catalysts. We showed that this effect enhances catalysis and improves visible light absorption for possible solar applications.