Coupling TiO2 with Nb carbide-based materials for H2 photoproduction: From 3D carbides to 2D MXenes
Adrià Sánchez, Guillermo Escolano‐Casado, Margarita Bania, Matthijs Koning, Jarosław Serafin, Pilar Ramı́rez de la Piscina, Lorenzo Mino, Narcı́s Homs
Abstract
In this work we coupled 3D Nb carbide, ternary layered NbMAX, and 2D NbMXene with TiO 2 , developing new photocatalysts for the renewable H 2 production from ethanol aqueous solutions. A new preparation method of Nb 2 CT x MXene is reported; the hydrothermal method proposed, uses NH 3(aq) and avoids the utilization of hazardous HF or a strong acid and fluoride salts. After thorough characterization of the structural and physico-chemical features of the materials, their photocatalytic performance has been related to their photoelectrochemical properties. Moreover, the interaction of the reactant molecules with the TiO 2 -based composites and their evolution under UV irradiation has been investigated by in situ IR spectroscopy. All composites showed a higher H 2 production rate and a higher lifetime of photogenerated charges (h + /e - ) than TiO 2 . The Nb 2 CT x -containing photocatalyst showed the best H 2 production yield, both in gas and liquid phase, owing to a very efficient transfer of the photogenerated electrons from the TiO 2 conduction band to the MXene phase, decreasing the rate of charge recombination and favoring the H 2 formation. The H 2 production of NbMXene/TiO 2 was more than 3.5 times that of TiO 2 and showed a stable behavior at least up to 7 h with light on/light off cycles.