Red light-inducible overall water-splitting photocatalyst, gold-inserted zinc rhodium oxide and bismuth vanadium oxide heterojunction, connected using gold prepared by sputtering in ionic liquid.

We prepared a solid-state Z-scheme photocatalyst in which zinc rhodium oxide (ZnRhO) and bismuth vanadium oxide (BiVO) that served as hydrogen (H) and oxygen (O) evolution photocatalysts, respectively, were connected with gold (Au) nanoparticles. The Au nanoparticles were prepared by sputtering in an ionic liquid, N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, to generate Au/ZnRhO/Au/BiVO with various amounts of Au in the 12 mol. %-29 mol. % range (vs 1.0 mol ZnRhO + 0.2 mol BiVO). Au/ZnRhO/Au/BiVO photocatalyzed overall pure-water splitting under irradiation with red light at a wavelength of 700 nm, and the dependence of the amounts of Au on the apparent quantum efficiency tended to increase in the measurement range.