过量Bi对BiFeO3薄膜光电阴极性能的影响,ACS Applied Energy Materials

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过量Bi对BiFeO3薄膜光电阴极性能的影响
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2023-12-05 , DOI: 10.1021/acsaem.3c01926
Nitin P. Prasad _{1,

2} , Marcus Rohnke ₃ , Marcel A. Verheijen ₄ , Jacobus M. Sturm ₅ , Jan P. Hofmann _{1,

6} , Emiel J. M. Hensen ₁ , Anja Bieberle-Hütter ₂

Affiliation

BiFeO ₃ (BFO) 由于其光吸收和光电化学特性，最近被认为是一种有前途的光电化学（PEC）水分解光电阴极材料。仍然需要了解性能限制因素，特别是化学计量对性能的影响。本研究研究了溶胶-凝胶合成前驱体溶液中 Bi/Fe 的比例对 BFO 薄膜的性质和性能的影响。在氟掺杂氧化锡基底上制备具有化学计量 Bi/Fe 比且 Bi 过量 10% 的薄膜。虽然本体表征技术显示了纯相 BFO 的形成，但表面表征技术表明 Bi 在表面富集。光吸收和带隙不随Bi过量而改变，而在0.6V vs RHE下，Bi过量薄膜的电流密度是化学计量薄膜的两倍。电化学阻抗谱将过量Bi薄膜的这种改进性能归因于较低的复合率和较低的电荷转移电阻。较低的复合率归因于可充当复合中心的 Bi 和 O 空位较少。因此，调整Bi/Fe比例是提高BFO光电阴极PEC性能的有效策略。

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Role of Excess Bi on the Properties and Performance of BiFeO3 Thin-Film Photocathodes

BiFeO₃ (BFO) has recently been identified as a promising photocathode material for photoelectrochemical (PEC) water splitting due to its light absorption and photoelectrochemical properties. The performance-limiting factors, in particular the impact of stoichiometry on the performance, still need to be understood. The effect of the ratio of Bi/Fe in the precursor solution for sol–gel synthesis on the properties and performance of BFO thin films is investigated in this study. Thin films with a stoichiometric Bi/Fe ratio and with a 10% excess of Bi are prepared on fluorine-doped tin-oxide substrates. While bulk characterization techniques show the formation of phase-pure BFO, surface characterization techniques indicate Bi enrichment on the surface. Light absorption and band gap do not change with excess Bi, whereas the current density is two times higher for Bi excess films compared to stoichiometric films at 0.6 V vs RHE. Electrochemical impedance spectroscopy attributes this improved performance of excess Bi thin films to a lower recombination rate and a lower charge transfer resistance. The lower recombination rate is attributed to fewer Bi and O vacancies, which can act as recombination centers. Therefore, adjusting the Bi/Fe ratio is an effective strategy to enhance the PEC performance of BFO photocathodes.

更新日期：2023-12-05

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