Metals free MWCNTs@TiO2@MMT heterojunction composite with MMT as a mediator for fast charges separation towards visible light driven photocatalytic hydrogen evolution
Metals free MWCNTs@TiO2@MMT heterojunction composite with MMT as a mediator for fast charges separation towards visible light driven photocatalytic hydrogen evolution
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DOI：
10.1016/j.apsusc.2018.08.240
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发表时间：
2019
影响因子：
6.7
通讯作者：
M. Umer;Muhammad Tahir;M. Azam;M. Jaffar
中科院分区：
文献类型：
--
作者：
M. Umer;Muhammad Tahir;M. Azam;M. Jaffar
使用在太阳能下发挥作用的低成本材料构建异质结是能源管理应用中高效制氢的重要途径。在本研究中，采用简便的溶胶-凝胶和湿浸渍方法设计和制造了分散在二维蒙脱石（MMT）纳米粘土中的多壁碳纳米管（MWCNT）改性TiO21D/0D异质结。通过 XRD、拉曼、FESEM、HRTEM、FTIR、UV-vis 和 PL 光谱技术对样品进行了表征。在2D MMT结构上分散1D/0D MWCNT/TiO2可扩展可见光吸收，缩短电荷迁移距离并提供丰富的活性位点。研究了样品在可见光照射下使用不同牺牲试剂的动态光催化析氢性能。 MWCNTs/TiO2/MMT异质结复合材料表现出最高的H2析出速率为1888ppmh−1，分别比MWCNTs/TiO2、MMT/TiO2和纯TiO2样品高约1.49、3.07和7.12倍。在不同的牺牲试剂中，由于存在连接到碳原子上的α-氢原子，使用甘油-水混合物获得了最高的H2产量。接下来，估计了光催化转化生产率（PTOP），它证明了分子 H2 生产率与光子能量利用率的关系。 MWCNT/TiO2/MMT 异质结复合材料实现了氢气生产的最大 PTOP，比使用裸 TiO2NPs 高 5.94 倍。由于 1D/OD/2D 异质结中 MWCNT/TiO2/MMT 之间的协同效应而提高的充电效率对于增强和动态 H2 析出至关重要。三元复合材料在制氢方面表现出优异且稳定的性能。本研究表明，用TiO2构建低成本耦合材料异质结可以为太阳能下制氢提供有效的途径。
Constructing heterojunctions with low-cost materials functional under solar energy is an important way for efficient hydrogen production for energy management applications. In this study, multiwall carbon nanotubes (MWCNTs) modified TiO21D/0D heterojunction dispersed in 2D montmorillonite (MMT) nanoclay was designed and fabricated using a facile sol-gel and wet impregnation approach. The samples were characterized by XRD, Raman, FESEM, HRTEM, FTIR, UV–vis and PL-spectroscopy techniques. Dispersing 1D/0D MWCNTs/TiO2on the 2D MMT structure extends visible light absorption, shorten charges migration distance and provides abundant active sites. The performance of samples was investigated for dynamic photocatalytic H2evolution with different sacrificial reagents under visible light irradiations. The MWCNTs/TiO2/MMT heterojunction composite exhibits the highest H2evolution rate of 1888 ppm h−1, which is about 1.49, 3.07 and 7.12 folds higher than MWCNTs/TiO2, MMT/TiO2and pure TiO2samples, respectively. Among the different sacrificial reagents, highest H2production was obtained using glycerol-water mixture due to the presence of α-hydrogen atoms attached to carbon atoms. Next, the photocatalytic turn-over productivity (PTOP) was estimated which demonstrated the molecular H2production rate with the photon-energy utilization. The maximum PTOP for H2production was achieved over MWCNTs/TiO2/MMT heterojunction composite, 5.94 times higher than using bare TiO2NPs. The improved charges efficiency due to the synergistic effect between MWCNTs/TiO2/MMT in 1D/OD/2D heterojunctions is critical for enhanced and dynamic H2evolution. The ternary composite exhibited excellent and stable performance for H2production. This study suggests that constructing heterojunction of low cost coupling materials with TiO2can provide an efficient way for H2production under solar energy.