MOFs衍生的二氧化钛促进Ti-Fe_(2)O_(3)光阳极高效光电化学水氧化的多重效应  

Unveiling the multiple effects of MOF-derived TiO_(2)on Ti-Fe_(2)O_(3)photoanodes for efficient and stable photoelectrochemical water oxidation

作　　者：巴凯凯 刘禹男 张凯[1] 王平 林艳红[1] 王德军[1] 李子亨[3] 谢腾峰[1] Kaikai Ba;Yuʼnan Liu;Kai Zhang;Ping Wang;Yanhong Lin;Dejun Wang;Ziheng Li;Tengfeng Xie(College of Chemistry,Jilin University,Changchun 130012,Jilin,China;Key Laboratory of Preparation and Applications of Environmental Friendly Material of the Ministry of Education,College of Chemistry,Jilin Normal University,Changchun 130103,Jilin,China;Key Laboratory of Physics and Technology for Advanced Batteries,College of Physics,Jilin University,Changchun 130012,Jilin,China)

机构地区：[1]吉林大学化学学院,吉林长春130012 [2]吉林师范大学化学学院,教育部环保材料制备与应用重点实验室,吉林长春130103 [3]吉林大学物理学院,先进电池物理与技术重点实验室,吉林长春130012

出　　处：《Chinese Journal of Catalysis》2024年第6期179-191,共13页催化学报（英文）

基　　金：国家自然科学基金(22172057);吉林省科技发展规划国际合作项目(20230402061GH).

摘　　要：光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有良好的化学稳定性、合适的带隙(~2.1 eV)、无毒、储量丰富等优点而成为最有前途的光阳极材料之一.然而,α-Fe_(2)O_(3)丰富的受体表面态和缓慢的水氧化动力学导致光生电荷复合严重,限制了其在光电化学中的实际应用.因此,有必要对α-Fe_(2)O_(3)进行表面工程设计以提高水氧化效率.本文提出了一种新方法,以金属有机框架(Ti-MOFs)为模板,在Ti-Fe_(2)O_(3)表面煅烧合成TiO_(2)层,然后将富活性位点的ZIF-67加载在TiO_(2)/Ti-Fe_(2)O_(3)上作为助催化剂,制备出具有较好光电化学性能的ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极.X射线衍射、高分辨透射电镜、X射线光电子能谱和拉曼光谱等表征结果证实成功合成了ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3).同时,氮气等温吸附脱附曲线和表面接触角测试结果表明,MOFs衍生的TiO_(2)为介孔材料.采用表面光伏技术、光致发光光谱、飞秒-瞬态吸收光谱和电化学阻抗谱分析,研究了光生电荷的分离和复合行为.结果表明,MOFs衍生的TiO_(2)不仅可以作为钝化层有效抑制了表面复合,还作为Ti-Fe_(2)O_(3)的电子阻挡层,显著减少了电子向表面的流失,从而大大提高了Ti-Fe_(2)O_(3)表面和体相的电荷分离效率.进一步的累积电荷量测试、电化学阻抗谱和Bode图分析显示,负载MOFs衍生TiO_(2)后,可以明显促进光生空穴向电解质的注入,其多孔结构也可以增加反应接触面积,这有利于光生电荷在固液界面传输.此外,理论计算结果表明,Ti-Fe_(2)O_(3)水氧化速控步骤的能垒(ΔG=3.38 eV)明显高于TiO_(2)(ΔG=1.67 eV),说明OER更容易在TiO_(2)/Ti-Fe_(2)O_(3)表面发生,这与其光电�α-Fe_(2)O_(3)is a promising photoanode that is limited by its high surface charge recombination and slow water oxidation kinetics.In this study,we synthesized a TiO_(2)layer on Ti-Fe_(2)O_(3)by annealing Ti-MOFs,followed by ZIF-67 as a co-catalyst,to fabricate a ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)photoanode for photoelectrochemical(PEC)water splitting.The systematic experimental and theoretical results revealed that the improvement in performance was due to multiple effects of the MOF-derived TiO_(2).This molecule not only passivates the acceptor surface states of Ti-Fe_(2)O_(3),thereby reducing the number of surface recombination centers,but also acts as an electron barrier to promote charge separation in the Ti-Fe_(2)O_(3)bulk.Moreover,MOF-derived TiO_(2)can dramatically reduce the energy barrier for the OER of Ti-Fe_(2)O_(3),thus promoting the conversion of the intermediate*OH into*O.The synergistic improvement in the bulk and surface properties effectively enhanced the water oxidation performance of Ti-Fe_(2)O_(3).The ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)photoanode exhibits a photocurrent density of up to 4.04 mA cm^(‒2)at 1.23 V vs.RHE,which is 9.4 times as that of pure Ti-Fe_(2)O_(3),and has long-term stability.Our work provides a feasible strategy for constructing efficient organic-inorganic hybrid photoelectrodes.

关 键 词：Ti-Fe_(2)O_(3)光阳极 电荷分离 多孔TiO_(2) 多重效应 水氧化 

分 类 号：TQ116.21[化学工程—无机化工] O643.36[理学—物理化学] O646[理学—化学]