Electronic structure and enhanced photoelectrocatalytic performance of Ru_(x)Zn_(1-x)O/Ti electrodes

Modification is one of the most important and effective methods to improve the photoelectrocatalytic(PEC)performance of ZnO.In this paper,the Ru_(x)Zn_(1-x)O/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 Ru^(4+) transferred into ZnO lattice and replaced a number of Zn^(2+),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 RuO_(2) 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 Ru_(x)Zn_(1-x)O/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.