Int. J. Energy Research, 46, 3674-3685 (2022) [pdf]

Strategy to Utilize Amorphous Phase of Semiconductor towards Excellent and Reliable Photochemical Water Splitting Performance: Roles of Interface Dipole Moment and Reaction Parallelization

Heechae Choi, Hyuksu Han, Sung-I Moon, Minyeong Je, Seungwoo Lee, Jiseok Kwon, Seungchul Kim, Kwang-Ryeol Lee, Ghulam Ali, Sanjay Mathur, Ungyu Paik, Shi-Zhang Qiao, Taeseup Song
 

Roles of amorphous phases in photochemical water splitting of semiconductors are still in debates, as the effects of amorphous phase are largely irregular even in a single material. We presumed that the photochemistry of crystal-amorphous mixed semiconductor systems would be governed by the interface characteristics, and conducted a systematic study to understand the origins of the largely varying photochemical reaction of semiconductors having amorphous phase. First-principles calculations on crystalline anatase and amorphous TiO2 showed that coexistence of crystalline and amorphous TiO2 and the exposure of the phase boundary are advantageous due to the accelerated charge separation by interface dipole moment and the parallelizable oxygen evolution reaction (OER) at the boundary. Our computation-based strategies were demonstrated in our experiments: only the TiO2 nanoparticle and nanotube having partial amorphization on surfaces have highly enhanced photocatalytic water splitting performances (~700%) compared to the pristine and completely-amorphized TiO2 systems.