Photoelectrocatalytic Oxidation Of Water And Benzyl Alcohol With Dye-senditized Photoanode

In view of the limited reserves of traditional fossil fuels and the resulting environmental pollution problems,considerable concerns were turned towards finding more sustainable and recyclable ways for energy storage and consumption.Among the available resources,solar energy is considered the most promising one.In order to convert solar energy into chemical fuels,hydrogen production by visible light-driven water splitting or oxidation of organic substrates with dye-sensitized photoelectrochemical cell?DSPEC?is an efficient approach.In this study,a series of pyridine derivatives as surface additives were modified on a molecular chromophore and water oxidation catalyst co-loaded TiO₂ photoanode,TiO₂|RuP,1?RuP=Ru?4,4?-?PO₃H₂?₂-2,2?-bipyridine??2,2?-bipyridine?₂,1=Ru?bda??L?₂,?bda=2,2?-bipyridine-6,6?-dicarboxylate,L=3-?pyridine-4-yloxy?decyl-phosphonic acid??.The addition of pyridine additives was found to result in up to 42%increase in photocurrent.Under simulated sun-light irradiation,TiO₂|RuP,1,P1?P1=4-Hydroxypyridine?produced a photocurrent density of 1 mA/cm² at a bias of 0.4 V vs.NHE in acetate buffer,which is among the best performance for dye-sensitized photoanodes.Moreover,the observed photocurrents are correlated with the electron-donating ability of the substituent groups on pyridine ring.Transient absorption measurements and electrochemical impedance spectroscopy revealed that surface-bound pyridine can effectively retard the back-electron transfer from the TiO₂conduction band to the oxidized dye,which is a major process responsible for energy loss in DSPECs.With TEMPO?2,2,6,6-tetramethylpiperidine-1-oxyl?as a redox mediator,RuP modified TiO₂ and core-shell SnO₂/TiO₂ films were developed as photoanodes for PEC oxidation of benzyl alcohol to benzyl aldehyde.Photoelectrochemical experiments showed that both photoanodes have the ability to drive TEMPO oxidation by sunlight and achieve the final oxidation of benzyl alcohol.Among them,the SnO₂/TiO₂ photoanode was found to exhibit the excellent activity and high stability.