Single-atomic-site platinum steers photogenerated charge carrier lifetime of hematite nanoflakes for photoelectrochemical water splitting

The achievable photocurrent of hematite, alpha-Fe2O3, is typically limited far below its theoretical limit. Here, the authors engineer single Pt atomic sites with surface oxygen vacancies into hematite photoanodes, which leads to enhanced photoelectrochemical water splitting. Although much effort has been devoted to improving photoelectrochemical water splitting of hematite (alpha-Fe2O3) due to its high theoretical solar-to-hydrogen conversion efficiency of 15.5%, the low applied bias photon-to-current efficiency remains a huge challenge for practical applications. Herein, we introduce single platinum atom sites coordination with oxygen atom (Pt-O/Pt-O-Fe) sites into single crystalline alpha-Fe2O3 nanoflakes photoanodes (SAs Pt:Fe2O3-Ov). The single-atom Pt doping of alpha-Fe2O3 can induce few electron trapping sites, enhance carrier separation capability, and boost charge transfer lifetime in the bulk structure as well as improve charge carrier injection efficiency at the semiconductor/electrolyte interface. Further introduction of surface oxygen vacancies can suppress charge carrier recombination and promote surface reaction kinetics, especially at low potential. Accordingly, the optimum SAs Pt:Fe2O3-Ov photoanode exhibits the photoelectrochemical performance of 3.65 and 5.30 mA cm(-2) at 1.23 and 1.5 V-RHE, respectively, with an applied bias photon-to-current efficiency of 0.68% for the hematite-based photoanodes. This study opens an avenue for designing highly efficient atomic-level engineering on single crystalline semiconductors for feasible photoelectrochemical applications.

Automated summary

The authors introduce single platinum atom sites with surface oxygen vacancies into hematite photoanodes, leading to enhanced photoelectrochemical water splitting.