Boosting Photocatalytic Water Oxidation on Photocatalysts with Ferroelectric Single Domains
Jiandong He, Yong Liu, Jiangshan Qu, Huichen Xie, Ruixue Lu, Fengtao Fan, Can Li*
Advanced Materials
https://onlinelibrary.wiley.com/doi/10.1002/adma.202210374
Ferroelectric materials are considered as promising photocatalysts due to their efficient charge separation via a polarization-induced built-in electric field. However, the polydomain structures hinder spatial charge separation and transfer due to the cancellation of polarization vectors in the domains. In this work, taking BiFeO3 (BFO) as a prototype, single-domain BFO nanosheets with visible-light absorption are prepared, as evident by piezoresponse force microscopy (PFM), spatially resolved surface photovoltage spectroscopy (SRSPS), and photodeposition experiments. The single-domain BFO nanosheets show nine times activity in photocatalytic water oxidation reaction under visible-light irradiation, compared with that of the polydomain BFO particles. With the asymmetric driving force for charge separation in a single domain, selective deposition of cocatalysts further enhances the photocatalytic activity of single-domain ferroelectric BFO nanosheets. These results demonstrate the role of the single-domain structure in constructing the driving force of charge separation in ferroelectric photocatalysts. The fabrication of single-domain structures in ferroelectric photocatalysts to achieve enhanced photocatalytic activity offers a path to efficiently utilize the photogenerated charges in solar energy conversion.
近日，我组在铁电光催化机理研究取得新进展。该工作以可见光响应的铁酸铋为原型，探究了铁电多畴和单畴构型对于其光催化性能的影响，并通过原位选择性光沉积助催化剂有效提高了其光催化水氧化活性，对铁电材料的光催化应用具有指导意义。
一直以来，提高光催化剂光生载流子分离效率是提高其太阳能利用率的关键之一。我组长期应用开发多种策略解决这一关键问题，如“异相结”（ Angew. Chem. Int. Ed. 2008, 47, 1766 –1769；Angew. Chem. Int. Ed., 2012，51: 13089-13092），“晶面间电荷分离”（ Nat. Commun. 2013, 4, 1432；Energy Environ. Sci., 2016, 9,2463；Nature，2022，610, 296–301；），“界面修饰”（J. Am. Chem. Soc. 2022, 144, 17540−17548；J. Am. Chem. Soc. 2016, 138, 13664−13672），“铁电极化”（Adv. Mater. 2020, 32, 1906513；Nat Commun. 2022, 13, 4245；Journal of Materials Chemistry A，2020，8，6863-6873）, “不对称光照”（ Nat Energy, 2018, 3(8): 655-663）, “异质结”（Advanced Materials，2019，31，1808185；Chem. Sci., 2023,14, 1861-1870；）。其中，在“铁电极化”研究方面，我组前期通过开尔文探针力显微镜研究了铁电电荷分离机制，发现未屏蔽的退极化场为其光生电荷分离的主要驱动力（Adv Mater, 2020, 32(7): 1906513）。之后，又通过在钛酸钡正负畴区构筑电荷收集纳米结构，实现了光催化全分解水。（Nat. Commun., 2022, 13(1): 4245）
铁电体通常状态下以多畴结构存在，因此造成极化矢量的抵消，以及光生电荷在畴壁处的聚集进而发生复合。首先，本工作通过多种表征手段首次证实了单畴态的铁酸铋纳米颗粒，并对比了不同畴的构型对于光催化水氧化活性的影响。研究结果表明，无论在模拟太阳光下还是可见光照射下，单畴态的铁酸铋其光催化活性要远优于多畴态的铁酸铋。并在退极化场驱动下，选择性光沉积了水氧化助催化剂，大幅提升其光催化性能。
相关成果以“Boosting Photocatalytic Water Oxidation on Photocatalysts with Ferroelectric Single Domains”为题，于近日发表在《先进材料》（Advanced Materials）上。该工作的共同第一作者是何建东(南开大学联合培养)和刘永博士，通讯作者是李灿院士。该工作得到国家重点研发计划、国家自然科学基金委“人工光合成”基础科学中心等项目的资助。（文/图 何建东、刘永）
文章链接： https://doi.org/10.1002/adma.202210374
