Abstract Hematite (α-Fe2O3) 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-Fe2O3 film with ultrasonic spray pyrolysis method. We show that the current density at 1.23 V vs. RHE (J ph@1.23V) under one-sun illumination can be improved from 10 to 130 μA/cm2 after optimizing the Sn dopant density. Moreover, J ph@1.23V 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.
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机译:摘要赤铁矿(α-Fe2O3)材料被认为是太阳能驱动的水分裂的有希望的候选者,因为成本低,化学稳定性和适当的带隙;然而,相应的系统性能受到差的导电性差,少数率的短扩散长度的限制,并且氧气进化反应缓慢。在这里,我们用超声波喷雾热解法介绍掺杂进入纳米云样α-Fe2O3薄膜的原位Sn。我们表明,在优化Sn掺杂剂密度之后,可以从10至130μA/ cm 2下提高123V与rhe(j ph@1.23v)的电流密度。此外,与通过快速热过程(RTP)相比,J pHOP@1.23V可以进一步增强25倍,其用于引入氧空位的缺陷掺杂。光电化学阻抗谱和Mott-Schottky分析表明性能改善可以归因于增加的载流子密度和对表面状态上的电荷捕获的降低的电阻和将表面电荷转移到电解质中的载体密度和降低的电阻。 X射线光电子光谱和X射线衍射确认存在Sn和氧气空位的存在,并讨论了不同水平的Sn掺杂和氧空位的潜在影响。我们的工作指出了一种有效改善金属氧化物半导体的光电化学性能的一种普遍方法。
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