Plasmon-enabled N(2) photofixation on partially reduced Ti(3)C(2) MXene

Benefiting from the superior conductivity, rich surface chemistry and tunable bandgap, Ti(3)C(2) MXene has become a frontier cocatalyst material for boosting the efficiency of semiconductor photocatalysts. It has been theoretically predicted to be an ideal material for N(2) fixation. However, the realization of N(2) photofixation with Ti(3)C(2) as a host photocatalyst has so far remained experimentally challenging. Herein, we report on a sandwich-like plasmon- and an MXene-based photocatalyst made of Au nanospheres and layered Ti(3)C(2), and demonstrate its efficient N(2) photofixation in pure water under ambient conditions. The abundant low-valence Ti (Ti((4−x)+)) sites in partially reduced Ti(3)C(2) (r-Ti(3)C(2)) produced by surface engineering through H(2) thermal reduction effectively capture and activate N(2), while Au nanospheres offer plasmonic hot electrons to reduce the activated N(2) into NH(3). The Ti((4−x)+) active sites and plasmon-generated hot electrons work in tandem to endow r-Ti(3)C(2)/Au with remarkably enhanced N(2) photofixation activity. Importantly, r-Ti(3)C(2)/Au exhibits ultrahigh selectivity without the occurrence of competing H(2) evolution. This work opens up a promising route for the rational design of efficient MXene-based photocatalysts.