In Situ Quantification of H2O2 Generated on Photocatalytic BiVO4 Films by Chemical Micromotors

Silver-coated Janus micromotors that self-propel in H2O2 are used to measure the H2O2 concentration produced on the surface of a photocatalytic BiVO4 film, because the motor speeds correlate linearly with the H2O2 concentration in the range of 0.5-1 mM. After UV exposure (780 mW/cm(2) for 40 s), a local H2O2 concentration of 0.72 mM on the film surface was inferred from the motor speeds, 75 times higher than the bulk average measured by iodometry. The micromotor sensors also help identify the optimal Pt loading on a BiVO4 film for highest H2O2 production and regions of high photocatalytic activity on a nonuniform BiVO4 film.