Insight into enhanced hydrogen evolution of single-atom Cu1/TiO2 catalysts from first principles

Developing efficient catalysts of low-cost transition metals for hydrogen production is of great importance but remains a huge challenge. Motivated by the idea of engineering local atomic configuration, we propose to focus on single metal atom confined in the lattice oxygen environment, as a class of non-Pt catalysts for hydrogen production. By first principles calculations, we study the characteristics and mechanism of hydrogen evolution reaction of single-atom Cu supported on anatase TiO2 catalysts, Cu1/TiO2. Cu preferentially sits on the bridge-centre site between two 2-fold coordinated O atoms (O2c) on the surface. Cu and coordinated O2c function as copper oxide species (-Cu-O-) in the reaction. The reaction starts with two isolated H respectively positioned on Cu and O2c, proceeds with a transfer of H from O2c to Cu, and eventually forms a H2 molecule. The free energy profiles indicate that Cu1/TiO2 exhibits excellent hydrogen evolution activity even better than Pt and MoS2. This study not only shows that single-atom Cu1/TiO2 is an excellent hydrogen evolution catalyst, but also expands the understanding of oxide species in single-atom catalysis and proposes an engineering local atomic configuration strategy for optimizing the design of single-atom catalysts for enhanced hydrogen production.