Surface and lattice engineered ruthenium superstructures towards high-performance bifunctional hydrogen catalysis

Developing high-performance bifunctional electrocatalysts towards the hydrogen evolution/oxidation reaction (HER/HOR) holds great significance for efficiently utilizing hydrogen energy. In this work, a unique class of Mo-modified Ru nanosheet assemblies (Mo-Ru NSAs) have been successfully prepared, where Mo possesses a unique configuration of both a metallic Mo atom and MoO3. Further structural optimization by density functional theory (DFT) calculations has revealed that the metallic Mo atom is embedded in the Ru lattice while MoO3 is adsorbed on a partially oxidized Mo atom. As a result, the surface electronic properties and lattice structures of Ru nanosheets have been dramatically altered, leading to optimized adsorption of intermediates and superior HER/HOR performance. In detail, 16 mV is sufficient to drive 10 mA cm(-2) for the HER in 1 M KOH with a durable stability of 250 h. Furthermore, a high mass activity of 2.45 A mg(Ru)(-1) towards the HOR in 0.1 M KOH with high stability is also achieved. DFT calculations have further revealed that the coupling of a Mo atom and MoO3 can facilitate the rapid decomposition of H2O and generate highly active sites by steric hindrance, thereby enabling high bifunctional activity. It is anticipated that this work would enlighten the construction of more advanced bifunctional catalysts via surface and lattice engineering.