Zhang Hemin, Park Jong Hyun, Byun Woo Jin, Song Myoung Hoon, Lee Jae Sung
School of Energy and Chemical Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Ulsan 44919 , Republic of Korea . Email:
Perovtronics Research Center , Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50 , Ulsan , 44919 , Republic of Korea.
Chem Sci. 2019 Oct 1;10(44):10436-10444. doi: 10.1039/c9sc04110a. eCollection 2019 Nov 28.
A simple electrochemical activation treatment is proposed to improve effectively the photoelectrochemical performance of Nb,Sn co-doped hematite nanorods. The activation process involves an initial thrice cathodic scanning (reduction) and a subsequent thrice anodic scanning (oxidation), which modifies both the surface and bulk properties of the Nb,Sn:FeO photoanode. First, it selectively removes the surface components to different extents endowing the hematite surface with fewer defects and richer Nb-O and Sn-O bonds and thus passivates the surface trap states. The surface passivation effect also enhances the photoelectrochemical stability of the photoanode. Finally, more Fe ions or oxygen vacancies are generated in the bulk of hematite to enhance its conductivity. As a result, the photocurrent density is increased by 62.3% from 1.88 to 3.05 mA cm at 1.23 V, the photocurrent onset potential shifts cathodically by ∼70 mV, and photoelectrochemical stability improves remarkably relative to the pristine photoanode under simulated sunlight (100 mW cm).
提出了一种简单的电化学活化处理方法，以有效提高铌、锡共掺杂赤铁矿纳米棒的光电化学性能。活化过程包括初始的三次阴极扫描（还原）和随后的三次阳极扫描（氧化），这会改变铌、锡共掺杂的Fe₂O₃光阳极的表面和体相性质。首先，它会选择性地不同程度去除表面成分，使赤铁矿表面具有更少的缺陷以及更丰富的Nb-O和Sn-O键，从而钝化表面陷阱态。表面钝化效应还增强了光阳极的光电化学稳定性。最后，在赤铁矿体相中产生更多的铁离子或氧空位以提高其导电性。结果，在1.23 V时，光电流密度从1.88 mA cm⁻²增加到3.05 mA cm⁻²，增幅为62.3%，光电流起始电位阴极方向移动约70 mV，并且相对于原始光阳极，在模拟太阳光（100 mW cm⁻²）下光电化学稳定性显著提高。
