Surface plasmon-polariton triggering of Ti3C2Tx MXene catalytic activity for hydrogen evolution reaction enhancement

The efficiency of green hydrogen production through photo- or electrochemical splitting of water depends strongly on the catalyst used. Several 2D materials have recently been proposed as effective catalysts or co-catalysts, and among them, oxygen-terminated MXenes deserve significant attention for both electro- and photo-induced water splitting. In this work, we described a hybrid photo-electrochemical approach based on the coupling of Ti3C2Tx MXene flakes on a plasmon-supported Au grating and light triggering of the electrocatalytic activity of the generated hybrid structure in a water splitting half reaction, namely, the hydrogen evolution reaction (HER). In particular, MXene flakes with both fluor and oxygen surface terminations were deposited on a periodic patterned gold surface that was capable of supporting surface plasmon-polariton (SPP) excitation under visible and near-infrared (NIR) light illumination. SPP excitation allows sub-diffraction focusing of light energy and effective enhancement of the electrocatalytic performance of Ti3C2Tx flakes. Under illumination, a significant enhancement of the HER kinetics was observed, as well as tuning of the HER rate-determining step from the Volmer step to the Heyrovsky step. In turn, we observed several-fold enhanced hydrogen evolution, which was attributed to plasmon-assisted hot charge carrier injection, with an additional contribution from the plasmon heating effect. The proposed Au grating/Ti3C2Tx hybrid structure allows utilization of the NIR part of the solar spectrum, which is commonly not used in water photolysis but achieves better efficiency in renewable energy-assisted green hydrogen production.