Synergistic enhancement of charge management and surface reaction kinetics by spatially separated cocatalysts and p-n heterojunctions in Pt/CuWO4/Co3O4 photoanode

Efficient charge separation and transport as well as fast surface reaction kinetics all play a vital role in the efficiency of solar water splitting. Herein, we first design and fabricate a highly efficient Pt/CuWO4/Co3O4 photoanode system for photoelectrochemical water splitting. CuWO4 is selectively decorated with Pt nanoparticles and Co3O4 on the inner and outer surfaces, respectively. The Pt underlayer serves as an electron capture layer to collect electron from CuWO4 to facilitate water reduction, while the p-type Co3O4 onto n-type CuWO4 not only constructs p-n heterojunction reducing the charge recombination at the interface of CuWO4/Co3O4, but also that Co3O4 can be used as cocatalyst to accelerate the surface water oxidation. This novel ternary Pt/CuWO4/Co3O4 structure exhibits a prominently enhanced photocurrent of 4.4 mA/cm2 at 1.23 V vs. RHE. These results demonstrate that synergistic effect of spatially separated cocatalysts and p-n heterojunctions in photoelectrode could effectively achieve improve photoelectrochemical performance for water splitting.