Carbon dots dominated photoelectric surface in titanium dioxide nanotube/nitrogen-doped carbon dot/gold nanocomposites for improved photoelectrochemical water splitting
2022
Liao, Fan | Shi, Yandi | Dang, Qian | Yang, Haiwei | Huang, Hui | Kang, Zhenhui | Shao, Mingwang
The dynamic behavior of electron-hole pairs at the interface of the nanocomposites is important for photoelectrochemical catalysis, but it is difficult to characterize. Here we construct a ternary titanium dioxide/nitrogen-doped carbon dot/gold (TiO₂/NCD/Au) complex as the model catalyst to investigate the kinetic indexes at their interfaces. Under irradiation (200 mW cm⁻²), the photocurrent density of TiO₂/NCD/Au is 10.26 mA cm⁻², which is higher than those of TiO₂/Au (4.34 mA cm⁻²), TiO₂/NCD (7.55 mA cm⁻²) and TiO₂ (3.34 mA cm⁻²). The evolved oxygen of TiO₂/NCD/Au reaches 125.8 μmol after 5000 s test. The energy bands of complexes are very similar to that of the unmodified TiO₂ catalyst due to the low content modification of NCDs and Au. In addition, the transient photovoltage (TPV) tests with a series of control samples show differences about the carriers’ separation and transfer process, which verify that Au can increase the separation quantity of electron-hole pairs while NCDs play a more important role on the increase of the separation quantity and separation rate simultaneously. This work quantifies the function of each component in a composite catalyst and deepens the understanding of the catalyst interface design.
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