Compensating Electronic Effect Enables Fast Site-to-Site Electron Transfer over Ultrathin RuMn Nanosheet Branches toward Highly Electroactive and Stable Water Splitting

To improve the electroactivity and stability of electrocatalysts, various modulation strategies have been applied in nanocatalysts. Among different methods, heteroatom doping has been considered as an effective method, which modifies the local bonding environments and the electronic structures. Meanwhile, the design of novel two-dimensional (2D) nanostructures also offers new opportunities for achieving efficient electrocatalysts. In this work, Mn-doped ultrathin Ru nanosheet branches (RuMn NSBs), a newly reported 2D nanostructure, is synthesized. With the ultrathin and naturally abundant edges, the RuMn NSBs have exhibited bifunctionalities of hydrogen evolution reaction and oxygen evolution reaction with high electroactivity and durability in different electrolytes. Experimental characterizations have revealed that Ru-O bonds are shortened due to Mn doping, which is the key factor that leads to improved electrochemical performances. Density functional theory (DFT) calculations have confirmed that the introduction of Mn enables flexible modulations on the valence states of Ru sites. The inversed redox state evolutions of Ru and Mn sites not only improve the electroactivity for the water splitting but also the long-term stability due to the pinning effect of Ru sites. This work has provided important inspirations for the design of future advanced Ru-based electrocatalysts with high performances and durability.