Two‐dimensional Mixed Phase Leaf‐Ti1‐xCuxO2 Sheets Synthesized Based on a Natural Leaf Template for Increased Photocatalytic H2 Evolution

Abstract

AbstractTwo‐dimensional (2D) leaf‐TiO2 (LTiO2) nano sheets were synthesized using a natural leaf template. In addition, 2D mixed phase leaf‐Ti1‐xCuxO2 sheets (1CuLTiO2) were prepared by incorporating Cu ions (1 wt %) into the LTiO2 lattice using a deposition‐precipitation method followed by a calcination process. Structural microscopic and spectroscopic analyses demonstrated the generation of anatase and rutile surface‐phase junctions as well as the combination of Cu ions with the disordered mesoporous leaf‐TiO2 lattice. Hydrogen evolution reactions over 1CuLTiO2 materials were performed using methanol as a sacrificial reagent under one sun illumination. LTiO2‐750, synthesized by calcination at 750 °C, showed an absorption onset at 410 nm, while LTiO2‐550, synthesized by calcination at 550 °C, exhibited an onset at 387 nm. Cu incorporation into the 1CuLTiO2‐750 lattice, synthesized by calcination at 750 °C, led to the increase in the visible light absorption. Both the photocurrent and hydrogen yield via 1CuLTiO2‐750 (apparent quantum yield, 4.9 %) were higher than the respective values of 1CuLTiO2‐550 (AQY=2.9 %) synthesized by calcination at 550 °C, highlighting the importance of the surface‐phase junction. The increased photocatalytic activity of 1CuLTiO2‐750 was mainly assigned to the formation of surface‐phase junctions, disordering mesoporosity, and 2D sheet morphology for fast charge carriers.