Au(111)@Ti6O11 heterostructure composites with enhanced synergistic effects as efficient electrocatalysts for the hydrogen evolution reaction

Developing cost-effective electrocatalysts for the hydrogen evolution reaction (HER) is of great significance for the renewable energy field. The Magneli phase TinO2n-1 (4 <= n <= 10) has attracted much attention as a promising carbon-free support for electrocatalysts due to its high electrical conductivity and favorable electrochemical stability. Herein, we report the synthesis of a specific crystal-plane coupling heterostructure between Au(111) nanoparticles (NPs) and Ti6O11 by photoreduction. Benefitting from the modification of the electronic structure and synergistic effects of the heterostructure, the electron density around Au atoms is enhanced, and the Gibbs free energy of hydrogen absorption (Delta G(H*)) was dramatically optimized to facilitate the HER process. The best electrocatalyst Au(111)@Ti6O11-50 exhibits a lower overpotential of 49 mV at a current density of -10 mA cm(-2) and a Tafel slope of 39 mV dec(-1) in 0.5 M H2SO4, and shows long-term electrochemical stability over 30 h. Au(111)@Ti6O11-50 shows a mass activity of 9.25 A mg(Au)(-1), which is about 18 times higher than that of commercial Pt/C (0.51 A mg(Pt)(-1)). Meanwhile, the density functional theory (DFT) calculations suggest that the Delta G(H*) of Au(111)@Ti6O11 is -0.098 eV, which is comparable to that of Pt (-0.09 eV). This work would be a powerful guide for the realization of efficient utilization of noble metals in catalysis.