Controlled Synthesis Of Ru-based Two-dimensional Nanomaterials For Hydrogen Evolution Reaction

As a crucial step in hydrogen generation by water splitting,the hydrogen evolution reaction(HER)has attracted tremendous research interest.In real applications,catalysts are usually needed to achieve low overpotential and fast kinetics,thus promoting energy conversion efficiency.Platinum(Pt)is acknowledged as the most efficient HER electrocatalyst.However,its scarcity and high cost limit the large-scale industrial applications of Pt-based catalysts,thus promoting the development of cost-effective alternatives with high electrocatalytic activities and robust stabilities.Ru-based two-dimensional materials have received considerable attention in recent years because of their attractive catalytic properties originating from their unique two-dimensional structure.However,the controlled synthesis of Ru-based two-dimensional nanomaterials still remains challenging,and the investigations of their HER performance are very limited.In this work,we have successfully synthesized Pd@Ru nanoplates,Pd@RuNi alloy nanoplates and Pd@RuAu alloy nanorings via seed-mediated growth methods with hexagonal Pd nanoplates as seeds,and investigated their catalytic properties toward HER.The main innovative results are summarized as follows:(1)We have successfully synthesized core-shell Pd@Ru nanoplates with a fcc structure by developing a facile solvothermal method using Pd nanoplates as seeds.By varying the amount of the Ru precursor,we can tune the thickness of Pd@Ru nanoplates at the atomic level,and even the crystal structure of Ru shells.With the increase in thickness of the Ru shells,the HER activity of the Pd@Ru nanoplates was first enhanced greatly due to the increase in Ru content and then dramatically decreased because of the structure transition of Ru from fcc to hcp.Among them,the Pd@Ru nanoplates with a thickness of 2.3 nm exhibit the optimal activity with good stability towards the HER,even outperforming commercial Ru/C and Pt/C catalysts in an alkaline solution.(2)We have successfully synthesized core-shell Pd@RuNi alloy nanoplates using Pd nanoplates as seeds.The lateral size and components of Pd@RuNi nanoplates can be tuned by varying the size of Pd seeds and the amount of metal precursor.Compared with Pd@Ru nanoplates,the alloying of Ru with Ni can significantly enhance their catalytic activities toward HER.Pd@RuNi nanoplates with different Ni content have different catalytic properties toward HER.Among them,the nanoplates with an atomic ratio of Pd:Ru:Ni?1:2.2:2.4 exhibit the optimal activity with good stability towards the HER,even outperforming commercial Ru/C and Pt/C catalysts in both acid and alkaline solutions.This seed-mediated growth method can also be extented to prepare Pd nanoplate supported Pd@RuAu alloy nanorings,which have better catalytic performance toward HER than Pd nanoplates with the same size.