Zhang Huiyu, Chen Yaping, Lu Rong, Li Ruiyu, Yu Anchi
Department of Chemistry, Renmin University of China, Beijing 100872, People's Republic of China.
Phys Chem Chem Phys. 2016 Jun 1;18(22):14904-10. doi: 10.1039/c6cp01600f.
Carbon nitrides (CN) have been widely used in photocatalytic applications. However, the charge carrier kinetics of CN after light excitation remains unclear. Herein, we prepared a stable and transparent CN colloid in an aqueous tetraethylammonium hydroxide solution and investigated its carrier kinetics using both femtosecond transient absorption and picosecond time-resolved fluorescence spectroscopy. We found that a new and positive absorption band appears in the femtosecond transient absorption spectrum of the CN colloid, which could be attributed to the absorption of the photogenerated electron/hole pairs (or the electronic excited state) of the CN colloid after light excitation. Moreover, we found that the charge carrier kinetics obtained from the femtosecond transient absorption measurements is dramatically different from that obtained from the picosecond time-resolved fluorescence measurements, indicating that the photophysical process of the CN colloid after light excitation is complicated. With the results obtained from both the femtosecond transient absorption and picosecond time-resolved fluorescence measurements, we proposed a schematic to understand the photophysics and charge carrier kinetics of the CN colloid. We believe that the current study is also significant for researchers to understand the photophysics and charge carrier kinetics of bulk CN.
碳氮化物（CN）已广泛应用于光催化领域。然而，光激发后CN的电荷载流子动力学仍不清楚。在此，我们在氢氧化四乙铵水溶液中制备了一种稳定且透明的CN胶体，并使用飞秒瞬态吸收光谱和皮秒时间分辨荧光光谱研究了其载流子动力学。我们发现，在CN胶体的飞秒瞬态吸收光谱中出现了一个新的正吸收带，这可归因于光激发后CN胶体中光生电子/空穴对（或电子激发态）的吸收。此外，我们发现，从飞秒瞬态吸收测量获得的电荷载流子动力学与从皮秒时间分辨荧光测量获得的电荷载流子动力学显著不同，这表明光激发后CN胶体的光物理过程很复杂。基于飞秒瞬态吸收和皮秒时间分辨荧光测量获得的结果，我们提出了一个示意图来理解CN胶体的光物理和电荷载流子动力学。我们相信，当前的研究对于研究人员理解块状CN的光物理和电荷载流子动力学也具有重要意义。
