Photocatalytic one‐pot multidirectional N‐alkylation over Pt/D‐TiO₂/Ti₃C₂: Ti₃C₂‐based short‐range directional charge transmission

Abstract

Visible-light-induced one-pot, multistep, and chemoselectivity adjustable reactions highlight the economical, sustainable, and green process. Herein, we report Pt nanoparticles dispersed on S and N co-doped titanium dioxide/titanium carbide (MXene) (3%Pt/D-TiO 2 /Ti 3 C 2 ) heterojunctions as photocatalysts for the tandem reactions between aromatic nitro compounds and alcohols to produce N-alkylated products. 3%Pt/D-TiO 2 /Ti 3 C 2 heterojunction was prepared by in situ grew TiO 2 on Ti 3 C 2 nanosheets, S and N co-doped TiO 2 with thiourea, and then Pt nanoparticles with 2.9 nm average diameter well dispersed on D-TiO 2 /Ti 3 C 2 . 3%Pt/D-TiO 2 /Ti 3 C 2 showed excellent activity and chemoselectivity to N-alkyl amines in the presence of base additive K 3 PO 4 under visible-light irradiation; interestingly the chemoselectivity almost completely switched to N-benzylideneanilines in the presence of base additive KOH. In comparison, Pt nanoparticles on S and N co-doped TiO 2 prepared from titanium carbide (3%Pt/D-TiO 2 @C) showed sharply decreased activity and chemoselectivity to N-alkyl amines or N-benzylideneanilines. The enhanced performance of 3%Pt/D-TiO 2 /Ti 3 C 2 should be attributed to the improvement in photogenerated electron and hole separation efficiency by means of charge short-range directional transmission caused by the intimate contact between the TiO 2 and the conductive Ti 3 C 2 . In situ DRIFTS spectra further verified that the substrates activation with visible-light irradiation at 25 C was much faster than heating.

Laser-Treated MXene as an Electrochemical Agent to Boost Properties of Semitransparent Photoelectrode Based on Titania Nanotubes

“…The O 1s spectrum of the Ti 3 C 2 T x sample before the laser ablation exhibits three peaks at 530.2 eV, 531.6 and 533.1 eV which are attributed to Ti−O−Ti, 82,83 Ti−OH, 83,84 and C− OH, 85 respectively (Figure 4c). After the Ti 3 C 2 T x laser annealing, only the peaks corresponding to the Ti−OH and C−OH bonds are present in the XPS spectrum.…”