A g-C₃N₄@Au@SrAl₂O₄:Eu²⁺,Dy³⁺composite as an efficient plasmonic photocatalyst for round-the-clock environmental purification and hydrogen evolution

Abstract

Here, we demonstrate a g-C3N4@Au@SrAl2O4:Eu2+,Dy3+ composite as a novel efficient self-luminous visible-light plasmonic photocatalyst for photocatalytic degradation of organic pollutants and hydrogen evolution from water around the clock.

Recent advances and prospects of persistent luminescent materials as inner secondary self-luminous light source for photocatalytic applications

“…This is because the persistent luminescent intensity and duration (about 10 min) of the ZnxGa2O3+x is not enough to efficiently degrade the RhB dye. Conversely, the degradation efficiency of the MB and RhB dyes can be continued for a relatively long time in the MPL@PCM composites where the MPLs can show the persistent duration for several hours, e.g., SrAl2O4:Eu,Dy@g-C3N4@Au [57], SrAl2O4:Eu,Dy@Ag3PO4 [64], Sr2MgSi2O7:Eu,Dy@Ag3PO4 [376], Sr2MgSi2O7:Eu,Dy@g-C3N4 [379], and NL-PA@BiOBr [381]. Besides, for instance, the BiOBr@NL-PA under a 300 W Xe lamp shows the improved photocatalytic RhB decomposition compared to the BiOBr PCM alone [381] (Figure 19d), which directly proves that the use of MPL@PCM composite is beneficial to the photocatalysis.…”

“…Recently, Liu et al [57] used the SrAl2O4:Eu 2+ ,Dy 3+ MPL in association with pristine g-C3N4-xAu PCM composites to design a novel self-luminous visible-light plasmonic photocatalyst composite (i.e., g-C3N4-Au@SrAl2O4:Eu 2+ ,Dy 3+ ) for photocatalytic hydrogen (H2) evolution (Figure 22). In this multiscale composite, the gold nanocrystals were introduced to expand the absorption range of g-C3N4 to the visible region in order to better overlap the emission band of the SrAl2O4:Eu 2+ ,Dy 3+ (Figure 22a).…”

“…The results reveal that the solar-to-hydrogen (STH) conversion efficiency under UV irradiation can be up to ~5.2%, which is slightly more than the highest STH conversion efficiency of 5 % for a particulate photocatalyst system [429][430][431]. In particular, the STH value can still be up to ~0.2 % in dark after removal of the UV light for 8 h. Moreover, the research conducted by Liu [57] and Cui et al [66] demonstrated that there are other factors that influence the photocatalytic efficiency of H2 and O2 production, among which the chemical nature and amounts of MPLs, PCMs, and MPL@PCM composite, the assistance of surface plasmonic effect for spectral adaptation, the photocatalytic cycles, chemical and thermal stability of MPLs, PCMs and MPL@PCM composite, the external photocatalytic working conditions such as the PH value, temperature, and irradiation conditions (Figure 23). These factors provide insights into directing the future photocatalytic works by use of MPLs as an inner excitation light source to keep the photocatalytic activity.…”

“…These factors provide insights into directing the future photocatalytic works by use of MPLs as an inner excitation light source to keep the photocatalytic activity. Since the persistent intensity of MPLs, such as SrAl2O4:Eu 2+ ,Dy 3+ [57] and NL-PA [381], can be gradually decreased in the absence of the external irradiation light, intermediately recharging the storage energy by re-exciting the MPL is a feasible approach to keep the persistent intensity at a certain intensity, leading to a new concept, i.e., "around-the-clock" photocatalytic activity.…”

“…Noteworthy is the recent design demonstrationhighly efficient photocatalytic reaction for the organic pollutants degradation and hydrogen evolution from the water through the self-activated (i.e., also called the external irradiation-free self-luminous) plasmonic photocatalyst composite g-C3N4@Ag@SrAl2O4:Eu 2+ ,Dy 3+ [57].…”