Physically Adsorbed Metal Ions in Porous Supports as Electrocatalysts for Oxygen Evolution Reaction

Abstract

Developing highly efficient and earth‐abundant electrocatalysts for the oxygen evolution reaction (OER) is significantly important for water‐splitting. Here, for the first time it is reported that the physically adsorbed metal ions (PAMI) in porous materials can be served as highly efficient OER electrocatalysts, which provides a universal PAMI method to develop electrocatalysts. This PAMI method can be applied to almost all porous supports, including graphene, carbon nanotubes, C3N4, CaCO3, and porous organic polymers and all the systems exhibit excellent OER performance. In particular, the as‐synthesized Co0.7Fe0.3CB exhibits a small overpotential of 295 mV and 350 mV at the current density of 10 mA cm−2 and 100 mA cm−2, respectively, which exceeds commercial 40 wt% IrO2/CB and most reported non‐noble metal‐based OER catalysts. Moreover, the mass activity of Co0.7Fe0.3CB reaches 643.4 A g−1 at the overpotential of 320 mV, which is nearly 4.7 times higher than that of 40 wt% IrO2/CB. In addition, the advanced ex situ and in situ synchrotron X‐ray characterizations are carried out to unravel the PAMI synthetic process. In short, this PAMI method will break the conversional understanding, i.e., the most OER catalysts are synthesized chemically, because the new PAMI method does not require any chemical synthesis, which therefore opens a new avenue for the development of OER electrocatalysts.

In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

“… 616 Moreover, the further oxidation of Fe 3+ species to a higher oxidation state was described, implying a high electrochemical activity of these sites. 617 , 618 …”

Ultra-small Ru nanoparticles embedded on Fe–Ni(OH)2 nanosheets for efficient water splitting at a large current density with long-term stability of 680 hours

“…18,19 However, the complexity of the composition and structure increases the difficulty of active site identification, so employing a facile method to prepare bifunctional catalysts equipped with well-defined active sites is crucial. NiFe metal oxide/hydroxide/oxyhydroxide have been extensively considered as the optimal metal combination to effectively catalyze the OER and our previous research demonstrated that NiFe hydroxide can be prepared easily via a simple physical adsorption of metal ion method at room temperature, 20–22 but on the other hand, their HER activity is unimpressive. Recent results indicated that Ru (Ru–Ni SNs, 23 Ru–MoO 2 , 24 Ni 3 Co x @Ru HNS, 25 RuNi–NSs@PANI, 26 RuPt/OMC, 27 and Ru 1 @Co/NC 28 ) displays comparable HER activity with Pt/C, thanks to the optimal H adsorption free energy.…”

Facile Synthesis of Carbon Cloth Supported Cobalt Carbonate Hydroxide Hydrate Nanoarrays for Highly Efficient Oxygen Evolution Reaction

“…To address such problems, the introducing carbon support and morphology modulation should be two important strategies for improving the OER activity of transition metal-based materials. Through the introducing carbon support, the electronic contact between the carbon support and the active materials can induce the charge redistribution and the changes in electronic structure of the active materials, probably leading to improve the electronic conductivity and facilitate charge transfer during the OER (Liu et al, 2018;Yang et al, 2020). For the morphology modulation, three-dimensional (3D) porous array structure presents significant advantages among various morphology, including large specific surface area, abundant exposed catalytically active sites, excellent structure stability, which are highly favorable for the mass and charge transfer during electrocatalytic reactions (Xu et al, 2018;Wang et al, 2020).…”