A hybrid CoOOH-rGO/Fe2O3 photoanode with spatial charge separation and charge transfer for efficient photoelectrochemical water oxidation
A hybrid CoOOH-rGO/Fe2O3 photoanode with spatial charge separation and charge transfer for efficient photoelectrochemical water oxidation
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DOI：
10.1016/j.jcat.2021.05.006
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发表时间：
2021-07
影响因子：
7.3
通讯作者：
R. Chong;Zhenzhen Wang;Jiaqi Lv;Jiayue Rong;Ling Zhang;Yushuai Jia;Li Wang;Zhixian Chang;Xiang Wang
中科院分区：
文献类型：
--
作者：
R. Chong;Zhenzhen Wang;Jiaqi Lv;Jiayue Rong;Ling Zhang;Yushuai Jia;Li Wang;Zhixian Chang;Xiang Wang
作为光电化学（PEC）水氧化的理想光阳极，Fe 2 O3的电荷迁移率低，电荷复合严重，表面析氧动力学缓慢。本文中，氢氧化钴（氧）与还原氧化石墨烯改性的Fe 2 O3（CoOOH-rGO/Fe 2 O3）偶联的混合光阳极通过利用螯合介导的原位生长方法的简易水热合成来良好地制作。形貌表征表明，rGO在孤立的Fe 2 O3之间形成内部网络，CoOOH纳米片分布在Fe 2 O3的末端，形成空间分离的纳米结构。结果表明，CoOOH-rGO/Fe 2 O3的起始电位明显降低，约为150 mV，在1.23 V时的光电流密度显著增加，约为2.56 mA cm-2，是Fe 2 O3的3.3倍。特别地，通过电化学阻抗谱、开路电位和强度调制光电流谱研究了rGO和CoOOH的功能。结果表明，rGO作为导电网络，促进了电子从Fe 2 O3向基底的转移，而CoOOH则明显钝化了Fe 2 O3的表面态，改善了电荷分离，为水的氧化提供了催化活性位. CoOOH和rGO引起的空间电荷分离和电荷转移是PEC水氧化性能增强的原因。这种合理的设计和简单的制作方法具有很大的潜力，可以应用于其他光电转换系统。
As a promising photoanode for photoelectrochemical (PEC) water oxidation, hematite (Fe2O3) still suffers from poor charge mobility and serious charges recombination and sluggish surface oxygen evolution kinetics. Herein, a hybrid photoanode of cobalt (oxy)hydroxide coupled with reduced graphene oxide modified Fe2O3(CoOOH-rGO/Fe2O3) is well crafted by a facile hydrothermal synthesis with a chelation-mediated in-situ growth method. Morphology characterizations indicate rGO forms the internal network among isolated Fe2O3and CoOOH nanosheets distribute on the terminal of Fe2O3, forming a spatial separated nanostructure. The resultant CoOOH-rGO/Fe2O3exhibits an obviously reduced onset potential ofca.150 mV and a significantly enhanced photocurrent density of 2.56 mA cm−2at 1.23 V, which isca.3.3 times higher than that of bare Fe2O3. Especially, the functions of rGO and CoOOH are studied by using electrochemical impedance spectroscopy, open circuit potentials and intensity modulated photocurrent spectroscopy. It is found rGO act as conductive network which facilitates the electron transfer from Fe2O3to the substrate, while CoOOH evidently passivate the surface states of Fe2O3, improve charge separation and provide catalytic active sites for water oxidation. The spatial charge separation and charge transfer caused by CoOOH and rGO are responsible for the enhanced PEC performance of water oxidation. The rational design and the facile fabrication strategy exhibit great potential to be used for other PEC system with great efficiency.