Xiao Chenhong, Zhou Zhongyuan, Li Liujing, Wu Shaolong, Li Xiaofeng
School of Optoelectronic Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, Jiangsu, China.
Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Laboratory of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou, 215006, Jiangsu, China.
Nanoscale Res Lett. 2020 Mar 4;15(1):54. doi: 10.1186/s11671-020-3287-1.
Hematite (α-FeO) material is regarded as a promising candidate for solar-driven water splitting because of the low cost, chemical stability, and appropriate bandgap; however, the corresponding system performances are limited by the poor electrical conductivity, short diffusion length of minority carrier, and sluggish oxygen evolution reaction. Here, we introduce the in situ Sn doping into the nanoworm-like α-FeO film with ultrasonic spray pyrolysis method. We show that the current density at 1.23 V vs. RHE (J) under one-sun illumination can be improved from 10 to 130 μA/cm after optimizing the Sn dopant density. Moreover, J can be further enhanced 25-folds compared to the untreated counterpart via the post-rapid thermal process (RTP), which is used to introduce the defect doping of oxygen vacancy. Photoelectrochemical impedance spectrum and Mott-Schottky analysis indicate that the performance improvement can be ascribed to the increased carrier density and the decreased resistances for the charge trapping on the surface states and the surface charge transferring into the electrolyte. X-ray photoelectron spectrum and X-ray diffraction confirm the existence of Sn and oxygen vacancy, and the potential influences of varying levels of Sn doping and oxygen vacancy are discussed. Our work points out one universal approach to efficiently improve the photoelectrochemical performances of the metal oxide semiconductors.
赤铁矿（α-FeO）材料因其成本低、化学稳定性好和带隙合适，被视为太阳能驱动水分解的一种有前景的候选材料；然而，相应体系的性能受到电导率差、少数载流子扩散长度短以及析氧反应迟缓的限制。在此，我们采用超声喷雾热解法将锡原位掺杂到纳米蠕虫状α-FeO薄膜中。我们表明，在优化锡掺杂剂密度后，在一个太阳光照下相对于可逆氢电极（RHE）在1.23 V时的电流密度（J）可从10 μA/cm²提高到130 μA/cm²。此外，通过用于引入氧空位缺陷掺杂的快速热退火（RTP）后处理，与未处理的对应物相比，J可进一步提高25倍。光电化学阻抗谱和莫特-肖特基分析表明，性能的提高可归因于载流子密度的增加以及表面态上电荷俘获和表面电荷转移到电解质中的电阻降低。X射线光电子能谱和X射线衍射证实了锡和氧空位的存在，并讨论了不同水平的锡掺杂和氧空位的潜在影响。我们的工作指出了一种有效提高金属氧化物半导体光电化学性能的通用方法。
