Abstract
AbstractCarbon is a frequently used electrode material and an important additive in catalyst films. Its corrosion is often reported during electrocatalysis at high anodic potentials, especially in acidic electrolyte. Investigation of the carbon corrosion in alkaline environment is difficult due to the CO2/CO32− equilibrium. We report the on‐line determination of electrolysis products generated on NixB/C hybrid electrocatalysts in alkaline electrolyte at anodic potentials using differential electrochemical mass spectrometry (DEMS). NixB/C catalyst films were obtained from mixtures containing different ratios of NiXB and benzoxazine monomers followed by polymerization and pyrolysis. The impact of the composition of the electrocatalyst on the dominant electrolysis process allows to distinguish between the oxygen evolution reaction and carbon corrosion using DEMS results as well as the catalyst surface composition evaluated from X‐ray photoelectron spectra. At the imposed highly oxidative conditions, an increasing amount of NixB in the electrocatalyst leads to a suppression of carbon corrosion.
Highlights
Carbon is a frequently used electrode material and an important additive in catalyst films
We demonstrated that common carbon additives used for the formulation of catalyst inks such as Vulcan XC 72, can undergo corrosion in alkaline environment, but the process is considerable diminished in the presence of highly active oxygen evolution reaction (OER) electrocatalysts such as e. g
In the last heating step, pyrolysis of the carbonaceous part of the composite occurs with the generation of a conductive Ndoped carbon matrix in which the active OER electrocatalyst, NixB, is embedded and stably immobilized on the electrode surface
Summary
Sandra Möller,[a] Stefan Barwe,[a] Stefan Dieckhöfer,[a] Justus Masa,[b] Corina Andronescu,*[c]. Introduction makes it thermodynamically unstable at the potentials higher than 1.23 V vs RHE necessary for the oxygen evolution reaction (OER).[3,5] Carbon corrosion can result in numerous soluble and insoluble products of organic and inorganic nature.[2,4,5] Typical oxidation products such as CO and CO2 [eqs. Carbon materials are employed to achieve higher surface areas, to reduce the amount of catalyst, to improve electrical conductivity of poorly conductive catalysts, and to stabilize catalyst particles on electrodes.[1] thermodynamic considerations paired with the harsh conditions during electrochemical water splitting point towards a high likelihood that carbonaceous materials undergo corrosion through dissolution, gasification, or exfoliation under formation of corrosion products.[2,3,4,5] Such processes would affect the carbon properties substantially, and typical consequences of carbon corrosion are the loss of electrochemically active surface area (ECSA), loss of electrical conductivity and a decreased stability of the overall catalyst film.
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