Hetero phase modulated hematite photoanodes for practical solar water splitting

Hematite is an excellent catalyst for solar water splitting but its practical performance is still low. In this work, a hetero phase of β-Fe2O3 was firstly introduced in α-Fe2O3 to optimize the internal structure, which can synergistically work with oxygen vacancy to enhance the charge extraction, facilitate the charge transport, and suppress the electron-hole recombination. As a result, the obtained hematite exhibits a high initial photocurrent of 2.72 mA/cm2 at 1.23 V vs. RHE, and can be well coupled with various further modifications such as P, Hf, and FeNiOOH to achieve an excellent photocurrent of 5.24 mA/cm2 at 1.23 V vs. RHE with a good stability over 100 h. Moreover, it can realize a benchmark solar-to-hydrogen conversion efficiency of 5.3% when connected to a commercial Si solar cell. The low cost, efficient, and stable hematite-based photoanodes may pave the way for practical solar water splitting.