Faster Electron Injection and More Active Sites for Efficient Photocatalytic H2 Evolution in g-C3 N4 /MoS2 Hybrid.
Faster Electron Injection and More Active Sites for Efficient Photocatalytic H2 Evolution in g-C3 N4 /MoS2 Hybrid.
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DOI：
10.1002/smll.201703277
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发表时间：
2018-03
期刊：
影响因子：
13.3
通讯作者：
Xiaowei Shi;M. Fujitsuka;Sooyeon Kim;T. Majima
中科院分区：
文献类型：
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作者：
Xiaowei Shi;M. Fujitsuka;Sooyeon Kim;T. Majima
本文研究了MoS_2作为助催化剂对g-C_3 N_4在可见光照射下光催化产氢活性的影响。利用单粒子光致发光（PL）和飞秒时间分辨瞬态吸收光谱（FT-IR），系统地研究了g-C3 N4与两种纳米结构MoS 2（纳米点和单层）之间的电荷转移动力学.单颗粒PL结果表明，g-C3 N4的发射被二硫化钼纳米点比二硫化钼单层更有效地淬灭。由瞬态吸收光谱测量计算出g-C3 N4 /MoS 2-纳米点杂化材料的电子注入速率和效率分别为5.96 × 109 s-1和73.3%，比g-C3 N4 /MoS 2-单层杂化材料的电子注入速率和效率分别提高了4.8倍和2.0倍。MoS 2纳米点和g-C3 N4之间更强的紧密结被认为是更快和更有效的电子注入的原因。此外，与单层二硫化钼相比，更多的不饱和末端硫原子可以作为活性位点在二硫化钼纳米点中。因此，g-C3 N4 /MoS 2纳米点表现出比g-C3 N4 /MoS 2单层（83.8 µmol g-1 h-1）高7.9倍的光催化活性（660 µmol g-1 h-1）。这项工作提供了深入了解g-C3 N4和纳米结构的MoS 2助催化剂之间的电荷转移，这可以为更合理地设计用于H2析出的MoS 2基催化剂开辟新的途径。
Herein, the structural effect of MoS2 as a cocatalyst of photocatalytic H2 generation activity of g-C3 N4 under visible light irradiation is studied. By using single-particle photoluminescence (PL) and femtosecond time-resolved transient absorption spectroscopies, charge transfer kinetics between g-C3 N4 and two kinds of nanostructured MoS2 (nanodot and monolayer) are systematically investigated. Single-particle PL results show the emission of g-C3 N4 is quenched by MoS2 nanodots more effectively than MoS2 monolayers. Electron injection rate and efficiency of g-C3 N4 /MoS2 -nanodot hybrid are calculated to be 5.96 × 109 s-1 and 73.3%, respectively, from transient absorption spectral measurement, which are 4.8 times faster and 2.0 times higher than those of g-C3 N4 /MoS2 -monolayer hybrid. Stronger intimate junction between MoS2 nanodots and g-C3 N4 is suggested to be responsible for faster and more efficient electron injection. In addition, more unsaturated terminal sulfur atoms can serve as the active site in MoS2 nanodot compared with MoS2 monolayer. Therefore, g-C3 N4 /MoS2 nanodot exhibits a 7.9 times higher photocatalytic activity for H2 evolution (660 µmol g-1 h-1 ) than g-C3 N4 /MoS2 monolayer (83.8 µmol g-1 h-1 ). This work provides deep insight into charge transfer between g-C3 N4 and nanostructured MoS2 cocatalysts, which can open a new avenue for more rationally designing MoS2 -based catalysts for H2 evolution.