Currently, RuO 2 is a benchmark acidic oxygen evolution reaction (OER) catalyst. Nevertheless, its wide applications are always restricted by slow dynamics and limited durability. This paper reports a type of Mn-doped RuO 2 nanocrystals for boosting the OER catalytic performance in acidic media. The catalyst (named Mn-RuO 2 ) is prepared through annealing of Ru-exchanged Mn-based derivative at 300 °C. Such Mn-RuO 2 exhibits excellent acidic OER activity, with an overpotential of 158 mV at 10 mA cm −2 and a stability of 5000 cycles in the presence of sulfuric acid (0.5 mol/L). Both structural characterization and theoretical analysis show that the Mn doping in RuO 2 can tune the d-band center of Ru active sites and lower antibonding surface-adsorbate states, which leads to a decreased free energy of the rate-determining step, ultimately enhancing the intrinsic activity of RuO 2 .

Graphene, a 2D material consisting of a single layer of sp -hybridized carbon, exhibits inert activity as an electrocatalyst, while the incorporation of heteroatoms (such as N) into the framework can tune its electronic properties. Because of the different electronegativity between N and C atoms, electrons will transfer from C to N in N-doped graphene nanosheets, changing inert C atoms adjacent to the N-dopants into active sites. Notwithstanding the achieved progress, its intrinsic activity in acidic media is still far from Pt/C. Here, a facile annealing strategy is adopted for Ir-doped metal-organic frameworks to synthesize IrCo nanoalloys encapsulated in N-doped graphene layers. The highly active electrocatalyst, with remarkably reduced Ir loading (1.56 wt%), achieves an ultralow Tafel slope of 23 mV dec and an overpotential of only 24 mV at a current density of 10 mA cm in 0.5 m sulfuric acid solution. Such superior performance is even superior to the noble-metal catalyst Pt. Surface structural and computational studies reveal that the superior behavior originates from the decreased ΔG for HER induced by the electrons transferred from the alloy core to the graphene layers, which is beneficial for enhancing CH binding.

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.