A Functionally Stable RuMn Electrocatalyst for Oxygen Evolution Reaction in Acid

Abstract

Proton exchange membrane water electrolysis (PEMWE) is a key technology to solve the serious energy and environmental problems. However, the poor durability of electrocatalysts in acidic oxygen evolution reaction (OER) environment hinders the large-scale application of PEMWE. Herein, a robust RuMn electrochemical catalyst with a remarkable durability within 20 000 cyclic voltammetry cycles is reported. Furthermore, RuMn is stable for 720 h at 10 mA cm -2 current density in 0.5 M H 2 SO 4 solution with <100 mV overpotential increase, outperforming the most electrocatalysts reported to date, by far. An amorphous RuO x shell is detected after the OER test, indicating a surface reconstruction process on the catalyst that inhibits steady-state dissolution. Further study demonstrates that the excellent durability of RuMn realized by protective RuO x can be attributed to strong bond strength of Ru, which is supported by density functional theory calculations with high dissolution voltage. Thus, improving the bond strength of Ru extends the design strategy for the Ru-based alloy catalysts with considerable stability.

Recent advances in amorphous electrocatalysts for oxygen evolution reaction

“…Reconstructed amorphization of RuO 2 promotes OER activity and stability in the harsh acidic condition ( Zhuang et al, 2019 ). Zhang and co-workers prepared amorphous RuO x shells on the surface of Ru or Ru-based alloys via electrooxidation process in acid ( An et al, 2022 ). The strong bond strength of Ru leads to the reconstruction of stable amorphous RuO x and inhibits steady-state dissolution on the surface.…”

Oxygen Evolution Electrocatalysts for the Proton Exchange Membrane Electrolyzer: Challenges on Stability

“…[14] Supported by the high U diss , Zhang et al verified that the increased bond strength of Ru in RuMn could inhibit the steady-state dissolution and protect amorphous RuO x in the process of surface reconstruction. [15] In the field of electrocatalysis, especially in the study of metal corrosion, Pourbaix diagram is an advantageous tool, which can help us assess the stability of catalysts under different operating potentials and pH. Based on the Gibbs free energy difference (∆G pbx ) between the materials and the stable component in the corresponding Pourbaix diagram as well as the energy above hull (E hull ) and band gap (E g ), Nørskov et al conducted highthroughput screening of more than 40 thousands materials in the Materials Project Database and obtained 68 robust catalysts with good electrochemical stability in acidic environments.…”

“…Similarly, a recent work also suggested that surface Mn leaching from RuMn alloy and the in situ formation of RuO x protective layer with a strong bond strength of Ru during dealloying (Figure 5d), were the reasons for the considerable stability of the catalyst, which was stable for 720 h at 10 mA cm −2 with a 100 mV increase in overpotential. [15] Moreover, Li et al designed a biphasic IrW-W 2 B alloy and conducted selective corrosion on W 2 B to form the IrW nanochannel structure (Figure 5e,f). [62] Impressively, the IrW nanochannels served as supports to protect the active Ir oxides against overoxidation by adsorbing redundant O atoms.…”

One Bifunctional Electrocatalyst Derived from Nickel MOF for Urea Oxidation Reaction and Hydrogen Evolution Reaction

“…Among them, methane hydrogen production 7 requires energy consumption and also produces pollutants. Electrolysis of water to make hydrogen is currently another common method for hydrogen production; 8 in the water electrolysis reaction, there are hydrogen evolution reaction (HER) 9 and oxygen evolution reaction (OER), 10 of which a larger potential is demanded for the anodic OER. 11 The result will also lead to energy consumption, thus limiting the rate of hydrogen production.…”