Yong Peng, Qingdong Ruan, Chun Ho Lam, Fanxu Meng, Chung-Yu Guan, Shella Permatasari Santoso, Xingli Zou, Edward T. Yu, Paul K. Chu, Hsien-Yi Hsu
Hematite (α-Fe2O3) is recognized as a promising photoelectrode material for photoelectrochemical (PEC) water splitting, as a result of its abundance, non-toxicity, suitable bandgap, and photochemical stability. Nevertheless, the undesirable physical and photophysical behaviors, such as poor conductivity, short diffusion length, and rapid charge-carrier recombination, seriously restrict PEC water splitting efficiency of hematite semiconductors. Herein, we fabricate nanoporous titanium (Ti)-doped α-Fe2O3 thin films by a facile hydrothermal reaction, subsequently utilizing energetic plasma ion implantation with a post-annealing process to significantly enhance the photoelectrochemical water oxidation performance of hematite. On the basis of materials characterization and electrochemical analysis, the optimized Ti-doped Fe2O3, i.e., Ti-4-Fe2O3, exhibits improved photocurrents of 0.55 and 1.07 mA cm−2 at 1.23 and 1.5 V versus RHE respectively under illumination of 100 mW/cm2 with AM 1.5 G spectrum, showing approximately 1.6-fold increases compared to pristine Fe2O3. We attribute this increase to improved charge carrier transport induced by Ti doping that reduces the recombination of light-driven charge carriers. The work utilizing plasma-assisted doping technique provides new insights into the surface engineering of photo-responsive semiconductors for the development of emerging hydrogen technologies. © 2021 Elsevier B.V.
School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong; Department of Physics, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong; Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong; Shenzhen Research Institute of City University of Hong Kong, Shenzhen, 518057, China; Institute of Microscale Optoelectronics, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China; Department of Environmental Engineering, National Ilan University, Yilan, 260, Taiwan; Chemical Engineering Department, Widya Mandala Surabaya Catholic University, East Java, Indonesia; Chemical Engineering Department, National Taiwan University of Science and Technology, Taipei, Taiwan; State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, Shanghai, 200444, China; Microelectronics Research Center, Department of Electrical and Computer Engineering, the University of Texas at Austin, Austin, 78758, United States