Fluorine Aided Stabilization of Pt Single Atoms on TiO$_2$ Nanosheets and Strongly Enhanced Photocatalytic H$_2$ Evolution

Abstract

Trapping sites in single atom (SA) catalysts are critical to the stabilization and reactivity of isolated atoms. Herein, we show that anchoring of Pt SAs on TiO$_2$ nanosheets is strongly aided by lattice incorporated fluorine species. Tailoring the speciation of fluorine on TiO$_2$ nanosheets is a key factor for uniform and stable dispersion of the Pt SAs and high efficiency in Pt SA co-catalyzed photocatalytic H$_2$ production. Fluorine-stabilized uniformly dispersed Pt SAs on the (001) surface of TiO$_2$ can provide a remarkable photocatalytic activity (a H$_2$ production rate of 45.3 mmol h$^{–1}$ mg$^{–1}$ Pt for 65 mW/cm2 365 nm light). This high (maximized) efficiency can be achieved with a remarkably low loading amount of Pt SAs on TiO$_2$ nanosheets (0.03 wt %), which is far superior to Pt nanoparticles on a TiO$_2$ nanosheet with the same or a higher loading amount. F-stabilized Pt SAs on TiO$_2$ nanosheets also exhibit an excellent stability in long-term photocatalytic reactions