Ni(OH)_(2)quantum dots as a stable cocatalyst modifiedα-Fe_(2)O_(3) for enhanced photoelectrochemical water-splitting  

Ni(OH)_(2)量子点助催化剂修饰α-Fe_(2)O_(3)光阳极增强光电分解水性能

作　　者：Jiayue Rong Zhenzhen Wang Jiaqi Lv Ming Fan Ruifeng Chong Zhixian Chang 荣佳悦;王珍珍;吕嘉奇;范明;种瑞峰;常志显(河南大学化学化工学院,河南省环境污染控制材料国际联合实验室,河南省镁合金腐蚀防护工程技术研究中心,河南开封475004)

机构地区：[1]Henan Joint International Research Laboratory of Environmental Pollution Control Materials,Henan Provincial Engineering Research Center of Green Anticorrosion Technology for Magnesium Alloys,College of Chemistry and Chemical Engineering,Henan University,Kaifeng 475004,Henan,China

出　　处：《Chinese Journal of Catalysis》2021年第11期1999-2009,共11页催化学报（英文）

基　　金：国家自然科学基金(U2004195,51502078);河南省高校青年骨干教师基金(2020GGJS036);河南省教育厅科技攻关(212102310505,192102310490,182102410090).

摘　　要：Depositing a cocatalyst has proven to be an important strategy for improving the photoelectrochemical(PEC)water-splitting efficiency of photoanodes.In this study,Ni(OH)2 quantum dots(Ni(OH)2 QDs)were deposited in situ onto anα-Fe_(2)O_(3)photoanode via a chelation-mediated hydrolysis method.The photocurrent density of the Ni(OH)2 QDs/α-Fe_(2)O_(3)photoanode reached 1.93 mA·cm^(−2)at 1.23 V vs.RHE,which is 3.5 times that ofα-Fe_(2)O_(3),and an onset potential with a negative shift of ca.100 mV was achieved.More importantly,the Ni(OH)2 QDs exhibited excellent stability in maintaining PEC water oxidation at a high current density,which is attributed to the ultra-small crystalline size,allowing for the rapid acceptance of holes fromα-Fe_(2)O_(3)to Ni(OH)_(2)QDs,formation of active sites for water oxidation,and hole transfer from the active sites to water molecules.Further(photo)electrochemical analysis suggests that Ni(OH)_(2)QDs not only provide maximal active sites for water oxidation but also suppress charge recombination by passivating the surface states ofα-Fe_(2)O_(3),thereby significantly enhancing the water oxidation kinetics over theα-Fe_(2)O_(3)surface.氢气具有无毒、能量密度高以及燃烧过程零污染等优点,被誉为是未来代替化石能源的优质新型能源载体.探索高效的、可持续的制氢技术对氢气能源发展至关重要.其中,光电化学水分解电池以太阳能作为驱动力将水分解成氢气和氧气,是解决能源和环境危机的理想途径之一.α-Fe_(2)O_(3)是一种窄带隙(~2.1 eV)半导体,可以吸收约40%的太阳光,同时具有天然丰度高、成本低等优点,是目前备受关注的光阳极材料.然而,由于α-Fe_(2)O_(3)空穴扩散距离短和表面产氧动力学慢等缺点,导致α-Fe_(2)O_(3)的光电分解水效率仍然较低.针对上述问题,目前主要通过掺杂、构建异质结和负载助催化剂等手段来改善其性能.其中,负载助催化剂可以有效降低水氧化活化能和促进表面电荷分离,是改善光阳极性能的有效手段.本文采用离子吸附和螯合剂调控水解两步法,将Ni(OH)2量子点(Ni(OH)_(2) QDs)原位生长于α-Fe_(2)O_(3)表面,成功构建了Ni(OH)_(2) QDs/α-Fe_(2)O_(3)复合光阳极.透射电子显微镜结果表明,Ni(OH)2以直径为3-5 nm的量子点附着于α-Fe_(2)O_(3)纳米棒表面,并形成独特且牢固的异质结结构.光电水氧化性能表明,所制备的Ni(OH)2 QDs/α-Fe_(2)O_(3)光电阳极表现出良好的光电性能,其光电流达到了1.93 mA·cm^(−2)(1.23 V vs.RHE),是单纯α-Fe_(2)O_(3)的3.5倍,且Ni(OH)2 QDs助催化剂使α-Fe_(2)O_(3)的起始电位降低了~100 mV.2 h稳定性测试结果表明,Ni(OH)_(2) QDs助催化剂在提升α-Fe_(2)O_(3)光电水氧化性能的同时,自身能够保持良好的稳定性,这在Ni(OH)_(2)作为光电水氧化助催化剂的研究中较为少见.通过电化学活性面积、开路电压、电化学阻抗谱、注入效率和强度调制光电流谱等表征了Ni(OH)_(2) QDs对α-Fe_(2)O_(3)光阳极和电解液界面电荷传输的影响.结果表明,Ni(OH)_(2) QDs不仅能充分暴露水氧化活性位点,促进载流子在界面快速迁移

关 键 词：Photoelectrochemical water splitting α-Fe_(2)O_(3) COCATALYST Ni(OH)_(2) Quantum dots 

分 类 号：TQ116.2[化学工程—无机化工] TQ426