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Substrate selection for fundamental studies of electrocatalysts and photoelectrodes: inert potential windows in acidic, neutral, and basic electrolyte.

Benck JD, Pinaud BA, Gorlin Y, Jaramillo TF - PLoS ONE (2014)

Bottom Line: In order to help researchers with the substrate selection process, we employ a consistent experimental methodology to evaluate the electrochemical reactivity and stability of seven potential substrate materials for electrocatalyst and photoelectrode evaluation.We determine the inert potential window for each substrate/electrolyte combination and make recommendations about which materials may be most suitable for application under different experimental conditions.Furthermore, the testing methodology provides a framework for other researchers to evaluate and report the baseline activity of other substrates of interest to the broader community.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Stanford University, Stanford, California, United States of America.

ABSTRACT
The selection of an appropriate substrate is an important initial step for many studies of electrochemically active materials. In order to help researchers with the substrate selection process, we employ a consistent experimental methodology to evaluate the electrochemical reactivity and stability of seven potential substrate materials for electrocatalyst and photoelectrode evaluation. Using cyclic voltammetry with a progressively increased scan range, we characterize three transparent conducting oxides (indium tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide) and four opaque conductors (gold, stainless steel 304, glassy carbon, and highly oriented pyrolytic graphite) in three different electrolytes (sulfuric acid, sodium acetate, and sodium hydroxide). We determine the inert potential window for each substrate/electrolyte combination and make recommendations about which materials may be most suitable for application under different experimental conditions. Furthermore, the testing methodology provides a framework for other researchers to evaluate and report the baseline activity of other substrates of interest to the broader community.

Show MeSH
Electrochemical activity and inert potential range for indium tin oxide (ITO).
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pone-0107942-g003: Electrochemical activity and inert potential range for indium tin oxide (ITO).

Mentions: The results of the progressive electrochemical cycling of ITO are shown in Figure 3. The sweeps in the cathodic region show several significant redox features apart from the hydrogen evolution reaction (HER) in all three electrolytes. The oxidative features (denoted a in Figure 3) appear only when sweeping towards positive potentials after a reductive current is drawn upon scanning to potentials of −0.55, −0.48, and −0.45 V vs. RHE in H2SO4, NaAc, and NaOH, respectively. On subsequent cycles, a corresponding reduction peak (denoted b in Figure 3) appears prior to the onset of hydrogen evolution. All features grow as the progressive scanning is extended to more negative potentials. These redox features are attributed to reduction of Sn and In to lower valence or metallic states and subsequent partial reoxidation/rereduction [1], [13], [20]. Previous work has shown by chemical analysis that these changes extend at least several nm deep [20]. It is also possible that some oxidized ions dissolve into solution and can plate back onto the electrode on subsequent cycles. This cycling of the redox states leads to irreversible changes to the electrode which degrade its electrical and optical properties. During cycling or when held at potentials more negative than −0.55 V vs. RHE, the ITO electrode is observed to turn gray in color due to the metal cation reduction, resulting in a significant decrease in its transparency.


Substrate selection for fundamental studies of electrocatalysts and photoelectrodes: inert potential windows in acidic, neutral, and basic electrolyte.

Benck JD, Pinaud BA, Gorlin Y, Jaramillo TF - PLoS ONE (2014)

Electrochemical activity and inert potential range for indium tin oxide (ITO).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214636&req=5

pone-0107942-g003: Electrochemical activity and inert potential range for indium tin oxide (ITO).
Mentions: The results of the progressive electrochemical cycling of ITO are shown in Figure 3. The sweeps in the cathodic region show several significant redox features apart from the hydrogen evolution reaction (HER) in all three electrolytes. The oxidative features (denoted a in Figure 3) appear only when sweeping towards positive potentials after a reductive current is drawn upon scanning to potentials of −0.55, −0.48, and −0.45 V vs. RHE in H2SO4, NaAc, and NaOH, respectively. On subsequent cycles, a corresponding reduction peak (denoted b in Figure 3) appears prior to the onset of hydrogen evolution. All features grow as the progressive scanning is extended to more negative potentials. These redox features are attributed to reduction of Sn and In to lower valence or metallic states and subsequent partial reoxidation/rereduction [1], [13], [20]. Previous work has shown by chemical analysis that these changes extend at least several nm deep [20]. It is also possible that some oxidized ions dissolve into solution and can plate back onto the electrode on subsequent cycles. This cycling of the redox states leads to irreversible changes to the electrode which degrade its electrical and optical properties. During cycling or when held at potentials more negative than −0.55 V vs. RHE, the ITO electrode is observed to turn gray in color due to the metal cation reduction, resulting in a significant decrease in its transparency.

Bottom Line: In order to help researchers with the substrate selection process, we employ a consistent experimental methodology to evaluate the electrochemical reactivity and stability of seven potential substrate materials for electrocatalyst and photoelectrode evaluation.We determine the inert potential window for each substrate/electrolyte combination and make recommendations about which materials may be most suitable for application under different experimental conditions.Furthermore, the testing methodology provides a framework for other researchers to evaluate and report the baseline activity of other substrates of interest to the broader community.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Stanford University, Stanford, California, United States of America.

ABSTRACT
The selection of an appropriate substrate is an important initial step for many studies of electrochemically active materials. In order to help researchers with the substrate selection process, we employ a consistent experimental methodology to evaluate the electrochemical reactivity and stability of seven potential substrate materials for electrocatalyst and photoelectrode evaluation. Using cyclic voltammetry with a progressively increased scan range, we characterize three transparent conducting oxides (indium tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide) and four opaque conductors (gold, stainless steel 304, glassy carbon, and highly oriented pyrolytic graphite) in three different electrolytes (sulfuric acid, sodium acetate, and sodium hydroxide). We determine the inert potential window for each substrate/electrolyte combination and make recommendations about which materials may be most suitable for application under different experimental conditions. Furthermore, the testing methodology provides a framework for other researchers to evaluate and report the baseline activity of other substrates of interest to the broader community.

Show MeSH