Fig. 6: Overall pathways for Cu-assisted BIOR on BiVO4 surface.

a CV curves of BiVO4 photoanodes measured in BI solutions containing 10 ppm Cu ions at variable scan rates. b Scan rate dependence of cathodic-to-anodic peak current ratio (Jpc/Jpa). c Second-order kinetic analysis of BI• radicals derived from peak current ratio evolution. d Illustration of the overall mechanism for BIOR in the Cu complex-BiVO4 system.