Ye Yifan, Thorne James E, Wu Cheng Hao, Liu Yi-Sheng, Du Chun, Jang Ji-Wook, Liu Erik, Wang Dunwei, Guo Jinghua
Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Department of Chemistry, Merkert Chemistry Center, Boston College , Chestnut Hill, Massachusetts 02467, United States.
J Phys Chem B. 2018 Jan 18;122(2):927-932. doi: 10.1021/acs.jpcb.7b06989. Epub 2017 Nov 15.
Photoelectrochemical (PEC) water splitting holds the potential as a direct route for solar energy conversation and storage. The performance of a PEC device is strongly influenced by the electronic properties of the photonanode surface. It has been shown that the synthesis methods can have a profound impact on the electronic properties and PEC performance of various photoelectrode materials such as hematite. Soft X-ray spectroscopic techniques, including O K-edge XAS and Fe L-edge XAS/XES, have been employed to investigate how the synthesis methods impact the electronic structure of resulting hematite materials. It is found that the hematite samples via solution regrowth methods show dramatically increased 3d-4sp band ratios in O K-edge XAS spectra and decreased relative elastic peak intensities in Fe L-edge RIXS spectra compared with samples synthesized via ALD or solution grown. The difference observed in O-K and Fe-L spectra indicated that solution regrowth strategy alters the O 2p-Fe 3d hybridization and hence the electronic structure of the hematite films, which proves to be beneficial for PEC performance of the hematite photoanode. Our findings provided new insights and potentially useful strategies for enhancing the PEC performance of photoanode materials.
光电化学（PEC）水分解作为太阳能转化和存储的直接途径具有潜力。PEC器件的性能受到光阳极表面电子性质的强烈影响。研究表明，合成方法会对诸如赤铁矿等各种光电极材料的电子性质和PEC性能产生深远影响。软X射线光谱技术，包括O K边X射线吸收精细结构（XAS）和Fe L边XAS/X射线发射光谱（XES），已被用于研究合成方法如何影响所得赤铁矿材料的电子结构。研究发现，与通过原子层沉积（ALD）或溶液生长法合成的样品相比，通过溶液再生长法制备的赤铁矿样品在O K边XAS光谱中显示出显著增加的3d-4sp能带比，在Fe L边共振非弹性X射线散射（RIXS）光谱中相对弹性峰强度降低。在O-K和Fe-L光谱中观察到的差异表明，溶液再生长策略改变了O 2p-Fe 3d杂化，从而改变了赤铁矿薄膜的电子结构，这被证明有利于赤铁矿光阳极的PEC性能。我们的研究结果为提高光阳极材料的PEC性能提供了新的见解和潜在有用的策略。
