Shallow doping at multiple energy levels to boost the photoelectrochemical activity of water-splitting α-Fe2O3 electrodes

• Published in: Research on chemical intermediates 2024-11, Vol.50 (11), p.5223-5234
• Main Authors: Hu, Yingfei, Cui, Haiyun, Huang, Huiting, Mao, Zhengguo, Lin, Qing, Guan, Hangmin, Wang, Yuanyuan, Wang, Jun
• Format: Article
• Language: English
• Subjects: Carrier density; Carrier recombination; Carrier transport; Catalysis; Chemistry; Chemistry and Materials Science; Current carriers; Dopants; Doping; Energy levels; Ferric oxide; Hematite; Inorganic Chemistry; N-type semiconductors; Niobium; Photoanodes; Photoelectric effect; Photoelectric emission; Physical Chemistry; Titanium; Water splitting
• ISSN: 0922-6168; 1568-5675
• DOI: 10.1007/s11164-024-05406-2

Hematite (α-Fe 2 O 3 ), an n-type semiconducting material, is considered one of the most promising photoanodes for water splitting, yet exhibits unsatisfactory photoelectrochemical (PEC) activity stemming from poor conductivity and inferior charge carrier transport. Doping is an effective strategy to improve conductivity and enhance carrier transport in α-Fe 2 O 3 . However, there is a limit of the doping method, because some dopants will pin the Fermi level via defect complexes and aggregate carrier recombination, leading to positive shift of onset potential and depressed saturated photocurrent. Herein, a strategy based on shallow dopants locating at multiple energy levels is developed to surpass the restriction by introducing niobium (Nb) into the titanium-doped Fe 2 O 3 (Ti-Fe 2 O 3 ) through post-treatment. The resulting Nb/Ti-Fe 2 O 3 composite film is confirmed to further increase the carrier concentration of Ti-Fe 2 O 3 and exhibit a 625% increase in saturated water-splitting photocurrent without positively shifted photocurrent onset. This study paves a new way for further advancement of the PEC water splitting.