Ultrasmall Ru/Cu-doped RuO2 Complex Embedded in Amorphous Carbon Skeleton as Highly Active Bifunctional Electrocatalysts for Overall Water Splitting.

Developing highly active electrocatalysts with superior durability for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in the same electrolyte is a grand challenge to realize the practical application of electrolysis water for producing hydrogen. In this work, an ultrasmall Ru/Cu-doped RuO2 complex embedded in an amorphous carbon skeleton is synthesized, through thermolysis of Ru-modified Cu-1,3,5-benzenetricarboxylic acid (BTC), as a highly efficient bifunctional catalyst for overall water splitting electrocatalysis. The ultrasmall Ru nanoparticles in the complex expose more activity sites for hydrogen evolution and outperform the commercial Pt/C. Meanwhile, the ultrasmall RuO2 nanoparticles exhibit superior oxygen evolution performance over commercial RuO2, and the doping of Cu into the ultrasmall RuO2 nanoparticles further enhances the oxygen evolution performance of the catalyst. The outstanding OER and decent HER catalytic activity endow the complex with impressive overall water splitting performance superior to that of the state-of-the-art electrocatalysts, which just require 1.47 and 1.67 V to achieve a current density of 10 mA cm-2 and 100 mA cm-2. The density functional theory calculations reveal that a Cu dopant could effectively tailor the d-band center, thereby tuning electronic structure of Ru activity sites on the RuO2 (110) plane and ultimately improving the OER performance of RuO2.