Selopal Gurpreet Singh, Mohammadnezhad Mahyar, Navarro-Pardo Fabiola, Vidal François, Zhao Haiguang, Wang Zhiming M, Rosei Federico
Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China.
Nanoscale Horiz. 2019 Mar 1;4(2):404-414. doi: 10.1039/c8nh00227d. Epub 2018 Nov 16.
Solar-driven photoelectrochemical (PEC) hydrogen (H) generation is a promising approach to harvest solar energy for the production of a clean chemical fuel. However, the low photon-to-fuel conversion efficiency and long-term stability of PEC devices are major challenges to be addressed to enable large-scale commercialization. Here we report a simple, fast and cost-effective approach to fabricate high efficiency and stable PEC devices for H generation, by fabricating a hybrid photoanode obtained by incorporating small amounts of multiwall carbon nanotubes (MWCNTs) into a TiO mesoporous film and sensitizing with colloidal heterostructured CdSe/(CdSeS)/(CdS) quantum dots (QDs). The latter were specially designed to accelerate the exciton separation through a band engineering approach. The PEC devices based on the TiO/QD-MWCNT (T/Q-M) hybrid photoanode with an optimized amount of MWCNTs (0.015 wt%) yield a saturated photocurrent density of 15.90 mA cm (at 1.0 V) under one sun illumination (AM 1.5G, 100 mW cm), which is 40% higher than that of the reference device based on TiO/QD (T/Q) photoanodes. This is attributed to a synergistic effect of the promising optoelectronic properties of the colloidal heterostructured QDs and improved electron transport (reduced charge transfer resistance) within the TiO-MWCNT hybrid anodes enabled by the directional path of MWCNTs for the photo-injected electrons towards FTO. Furthermore, the PEC device based on the T/Q-M hybrid photoanode is more stable (∼19% loss of its initial photocurrent density) when compared with the T/Q photoanode (∼35% loss) after two hours of continuous one sun illumination. Our results provide fundamental insights and a different approach to improve the efficiency and long-term stability of PEC devices and represent an essential step towards the commercialization of this emerging solar-to-fuel conversion technology.
太阳能驱动的光电化学（PEC）制氢是一种很有前景的获取太阳能以生产清洁化学燃料的方法。然而，PEC装置的低光子到燃料转换效率和长期稳定性是实现大规模商业化需要解决的主要挑战。在此，我们报告一种简单、快速且经济高效的方法来制造用于制氢的高效稳定PEC装置，即通过将少量多壁碳纳米管（MWCNT）掺入TiO介孔膜并使用胶体异质结构CdSe/(CdSeS)/(CdS)量子点（QD）进行敏化来制备混合光阳极。后者是通过能带工程方法专门设计用于加速激子分离的。基于TiO/QD-MWCNT（T/Q-M）混合光阳极且MWCNT含量优化（0.015 wt%）的PEC装置在一个太阳光照（AM 1.5G，100 mW cm）下产生的饱和光电流密度为15.90 mA cm（在1.0 V时），比基于TiO/QD（T/Q）光阳极的参考装置高40%。这归因于胶体异质结构量子点有前景的光电特性以及MWCNT为光注入电子朝向FTO提供的定向路径使TiO-MWCNT混合阳极内电子传输得到改善（电荷转移电阻降低）的协同效应。此外，与T/Q光阳极（连续一个太阳光照两小时后初始光电流密度损失约35%）相比，基于T/Q-M混合光阳极的PEC装置更稳定（初始光电流密度损失约19%）。我们的结果为提高PEC装置的效率和长期稳定性提供了基本见解和一种不同的方法，并代表了这种新兴的太阳能到燃料转换技术商业化的关键一步。
