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Modification is one of the most important and effective methods to improve the photoelectrocatalytic (PEC) performance of ZnO. In this paper, the RuxZn1−xO/Ti electrodes were prepared by thermal decomposition method and the effect of Ru content on those electrodes’ electronic structure was analyzed through the first-principles calculation. Various tests were also performed to observe the microstructures and PEC performance. The results showed that as the Ru4+ transferred into ZnO lattice and replaced a number of Zn2+, the conduction band of ZnO moved downward and the valence band went upward. The number of photogenerated electron-hole pairs increased as the impurity levels appeared in the band gap. In addition, ZnO nanorods exhibited a smaller grain size and a rougher surface under the effect of Ru. Meanwhile, the RuO2 nanoparticles on the surface of ZnO nanorods acted as the electron-transfer channel, helping electrons transfer to the counter electrode and delaying the recombination of the electron-hole pairs. Specifically, the RuxZn1−xO/Ti electrodes with 9.375 mol% Ru exhibited the best PEC performance with a rhodamine B (RhB) removal rate of 97%, much higher than the combination of electrocatalysis (EC, 12%) and photocatalysis (PC, 50%), confirming the synergy of photoelectrocatalysis.

Exploring composite materials with ideal structures is an effective way to achieve synergy among different functional components. In this paper, a thermal decomposition method was adopted to prepared IrO2–CeO2-graphene/Ti composite electrodes. The influence of adding graphene on the composite material's electronic structure was analyzed by first-principles calculations, and its microstructure and electrochemical performance were also observed though various tests. The results indicated that coatings containing graphene exhibited a hierarchical porous structure, which could enlarge the specific surface area effectively. The band gaps of the IrO2–CeO2 composite oxides were filled by the energy level of C, which reduced the electron-transfer resistance. With amorphous CeO2 and the graphene acting as highly efficient ion-diffusion and electron-transfer channels respectively, the electrodes' charge storage performances were improved. The electrodes' specific capacitance values rose at first, then decreased as the graphene contents increased, reaching a maximum of 368 F g−1 when the content was 2 mg mL−1. However, adding graphene could harm the electrodes' cycling stability; excessive graphene could also encapsulate IrO2 nanoparticle and hinder contact with the electrolyte, thus reducing the electrodes' specific capacitances.