Coupling NiCo catalysts with carbon quantum dots on hematite photoanodes for highly efficient oxygen evolution

Highly efficient hole transfer from photoanodes to oxygen evolution catalysts is crucial for solar photoelectrochemical (PEC) water splitting. Herein, we demonstrated the coupling of the NiCo catalyst with carbon quantum dots (CDs) on the surfaces of alpha-Fe2O3 photoanodes, resulting in one of the highest currently known PEC activities of 4.26 mA cm(-2) (1.23 V versus the reversible hydrogen electrode, AM 1.5G). Furthermore, the H-2 generation rate from PEC water splitting could reach up to 74.9 mu mol cm(-2) h(-1) with a faradaic efficiency of nearly 99%. The detailed experimental results clearly reveal that these CDs acted as an efficient medium for remarkably promoting hole transport from anodes to catalysts and selectively tailoring the electronic structure of surface-active sites, which significantly promoted the surface charge separation and oxygen evolution process. This work offers unique insights into the design and construction of highly efficient photoanodes for PEC water splitting applications.

Automated summary

This study demonstrated highly efficient hole transfer from photoanodes to oxygen evolution catalysts by coupling NiCo catalyst with carbon quantum dots on alpha-Fe2O3 photoanodes, achieving one of the highest PEC activities and H2 generation rates. The carbon quantum dots acted as an efficient medium to promote hole transport and selectively tailor the electronic structure of surface-active sites, significantly enhancing surface charge separation and oxygen evolution process.