Electrochemical determination of the degree of atomic surface roughness in Pt–Ni alloy nanocatalysts for oxygen reduction reaction

Abstract

Pt-Ni alloy nanocrystals with Pt-enriched shells were prepared by selective etching of surface Ni using sulfuric acid and hydroquinone. The changes in the electronic and geometric structure of the alloy nanoparticles at the surface were elucidated from the electrochemical surface area, the potential of zero total charge (PZTC), and relative surface roughness, which were determined from CO-and CO 2 -displacement experiments before and after 3000 potential cycles under oxygen reduction reaction conditions. While the highest activity and durability were achieved in hydroquinone-treated Pt-Ni, sulfuric acidtreated one showed the lower activity and durability despite its higher surface Pt concentration and alloying level. Both PZTC and Q CO 2 /Q CO ratio (desorption charge of reductively adsorbed CO 2 normalized by CO ad -stripping charge) depend on surface roughness. In particular, Q CO 2 /Q CO ratio change better reflects the roughness on an atomic scale, and PZTC is also affected by the electronic modification of Pt atoms in surface layers. In this study, a comparative study is presented to find a relationship between surface structure and electrochemical properties, which reveals that surface roughness plays a critical role to improve the electrochemical performance of Pt-Ni alloy catalysts with Pt-rich surfaces.

High‐Temperature Confinement Synthesis of Supported Pt–Ni Nanoparticles for Efficiently Catalyzing Oxygen Reduction Reaction

“…This suggests that the compressive strain is beneficial to ORR activity. [ 42–44 ] Based on the above analysis, we propose that the surface compressive strain and the d‐band center down‐shift from Ni alloying‐dealloying process weaken Pt–O binding strength, thus resulting in the outstanding ORR activity of PtNi 3 @OMC‐A.…”

Modulating heterointerfaces of tungsten incorporated CoSe/Co3O4as a highly efficient electrocatalyst for overall water splitting

“…The global demand for renewable and clean energy sources has exclusively increased due to the enormous consumption of fossil fuels and environmental impact. [1][2][3][4] Hydrogen is known to be one of the best alternative fuels because of its high energy density and sustainability. However, conventional hydrogen production is still carried out from natural gas, which releases carbon during the process.…”

“…5 In general, water splitting includes two half-reactions, namely the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), which require a high overpotential and present sluggish kinetics. 3,6 To overcome these issues, much effort has been made to develop a highly active electrochemical catalyst and reduce the overpotential. [7][8][9] Traditionally, noble metal-based materials such as Pt, RuO 2 , and IrO 2 were displayed as highly active catalysts for the HER and OER, which could efficiently enhance the dynamic kinetics and reduce the overpotential.…”

Self‐catalyzed formation of strongly interconnected multiphase molybdenum‐based composites for efficient hydrogen evolution

“…As one of the key half‐reactions in water splitting, the highly efficient hydrogen evolution reaction (HER) is crucial for the industrial application of electrochemical water splitting 1–4 . Platinum‐group metals are flagship catalysts for HER, but restricted rare earth reserves and high costs limit their universal application 5–7 . Molybdenum carbide (Mo x C) with a Pt‐like electronic structure, good conductivity, and corrosion resistance has shown great potential in HER catalysis and is worthy of in‐depth exploration 8–10 …”

“…[1][2][3][4] Platinum-group metals are flagship catalysts for HER, but restricted rare earth reserves and high costs limit their universal application. [5][6][7] Molybdenum carbide (Mo x C) with a Pt-like electronic structure, good conductivity, and corrosion resistance has shown great potential in HER catalysis and is worthy of in-depth exploration. [8][9][10] Since the Leonard group first revealed the HER catalytic performance of Mo x C in four phases (α-MoC, β-Mo 2 C, η-MoC, and γ-MoC), optimization of the four phases has been relentlessly pursued.…”