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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.

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Potential range in which each substrate is inert for all electrolytes.Chemical stability is indicated by the color of the trace.
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pone-0107942-g010: Potential range in which each substrate is inert for all electrolytes.Chemical stability is indicated by the color of the trace.

Mentions: We employed a threshold current density of 50 µA/cm2 to determine the potential boundaries at which each substrate could no longer be considered electrochemically inert. Each substrate has a different value of capacitance so this 50 µA/cm2 was measured above the baseline capacitive current. Any initial transients were ignored. The actual potential at which this threshold is first reached was taken and the window of inertness of each substrate is shown in Figure 10. The chemical stability of the substrate in each electrolyte, relevant for longer term testing (>1 hr), is also indicated. In general, the TCOs have wide windows of inertness but are less stable than the opaque substrates. The GC and HOPG also draw very little current over a wide potential range and are very stable in all electrolytes. The results in Figure 10 should provide an excellent starting point for researchers in the selection of substrate materials for electrochemical studies. For example, FTO and ITO are suitable substrates for the study of thick, semiconducting photoelectrocatalysts while GC and HOPG are more appropriate for evaluating the activity of nanoparticulate or other low coverage catalysts. While some of these points were already known among experienced researchers in the field (though a substrate selection rationale is often omitted from published manuscripts), here we have quantified the useable potential windows for these important substrates to facilitate the substrate process for researchers in the future.


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)

Potential range in which each substrate is inert for all electrolytes.Chemical stability is indicated by the color of the trace.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0107942-g010: Potential range in which each substrate is inert for all electrolytes.Chemical stability is indicated by the color of the trace.
Mentions: We employed a threshold current density of 50 µA/cm2 to determine the potential boundaries at which each substrate could no longer be considered electrochemically inert. Each substrate has a different value of capacitance so this 50 µA/cm2 was measured above the baseline capacitive current. Any initial transients were ignored. The actual potential at which this threshold is first reached was taken and the window of inertness of each substrate is shown in Figure 10. The chemical stability of the substrate in each electrolyte, relevant for longer term testing (>1 hr), is also indicated. In general, the TCOs have wide windows of inertness but are less stable than the opaque substrates. The GC and HOPG also draw very little current over a wide potential range and are very stable in all electrolytes. The results in Figure 10 should provide an excellent starting point for researchers in the selection of substrate materials for electrochemical studies. For example, FTO and ITO are suitable substrates for the study of thick, semiconducting photoelectrocatalysts while GC and HOPG are more appropriate for evaluating the activity of nanoparticulate or other low coverage catalysts. While some of these points were already known among experienced researchers in the field (though a substrate selection rationale is often omitted from published manuscripts), here we have quantified the useable potential windows for these important substrates to facilitate the substrate process for researchers in the future.

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