Steering interfacial charge kinetics: Synergizing cocatalyst roles of Ti3C2Mx (MXene) and NCDs for superior photocatalytic performance over TiO2

Abstract

Steering the kinetics of photoexcited electron-hole pairs to achieve the elongated lifetime of carrier is one of key strategies to enhance the photocatalytic performance. Here, 0D/2D/2D NCDs/TiO2/Ti3C2Mx photocatalyst is fabricated for the first time via hydrothermal route, the mixed group terminated MXene (Ti3C2Mx, M = -O, –OH, -F) and N-doped carbon dots (NCDs) are exploited as an electron acceptor and hole mediator, respectively, enhancing the photocatalytic activity of TiO2 nanosheets by steering interfacial charge kinetics. The photocatalytic hydrogen evolution and tetracycline hydrochloride (TC) degradation of 0.1 NCDs/TiO2/Ti3C2Mx-12 h are ∼ 4 and 9 times higher than those of TiO2, respectively. UPS and DFT calculation results determine that the work function (Φ) of Ti3C2Mx as 4.16 eV and 3.63 eV, respectively, which are larger than that of bare Ti3C2 (Φ = 3.55 eV), while the work function of TiO2 and NCDs are 3.98 and 3.09 eV, respectively. The results of charge transfer dynamics reveal that the photocatalytic enhancement of NCDs/TiO2/Ti3C2Mx is dominantly attributed to the synergizing cocatalyst roles of Ti3C2Mx (MXene) and NCDs. The insight into the surface termination dominated electronic property of MXene and synergistic steering the interfacial charge kinetics is an effective way to fabricate high performance MXene-based photocatalysts.