Meso-Structured Platinum Thin Films: Active and Stable Electrocatalysts for the Oxygen Reduction Reaction

Improving both the activity and the stability of the cathode catalyst in platinum-based polymer electrolyte fuel cells is a key technical challenge. Here, we synthesize a high surface area meso-structured Pt thin film that exhibits higher specific activity for the oxygen reduction reaction (ORR) than commercial carbon-supported Pt nanoparticles (Pt/C). An accelerated stability test demonstrates that the meso-structured Pt thin film also displays significantly enhanced stability as compared to the commercial Pt/C catalyst. Our study reveals the origin of the high turnover frequency (TOF), and excellent durability is attributed to the meso-structure, which yields a morphology with fewer undercoordinated Pt sites than Pt/C nanoparticles, a key difference with substantial impact to the surface chemistry. The improved catalyst activity and stability could enable the development of a high-performance gas diffusion electrode that is resistant to corrosion even under the harsh conditions of start-up, shut-down, and/or hydrogen starvation

Correction: Substrate Selection for Fundamental Studies of Electrocatalysts and Photoelectrodes: Inert Potential Windows in Acidic, Neutral, and Basic Electrolyte

<p>Correction: Substrate Selection for Fundamental Studies of Electrocatalysts and Photoelectrodes: Inert Potential Windows in Acidic, Neutral, and Basic Electrolyte</p

Substrate Selection for Fundamental Studies of Electrocatalysts and Photoelectrodes: Inert Potential Windows in Acidic, Neutral, and Basic Electrolyte

<div><p>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.</p></div

Area-normalized circuit resistances.

<p>Area-normalized circuit resistances.</p

Fluorine-doped tin oxide (FTO) substrate scanned over a single potential range and hydrogen evolution catalyzed by amorphous molybdenum sulfide on FTO.

<p>Fluorine-doped tin oxide (FTO) substrate scanned over a single potential range and hydrogen evolution catalyzed by amorphous molybdenum sulfide on FTO.</p

Electrochemical activity and inert potential range for fluorine-doped tin oxide (FTO).

<p>Inset for each electrolyte shows polarization curves for continuous cycling within the inert potential range for a period of 2 hours.</p

Testing methodology.

<p>Testing methodology.</p

Electrochemical activity and inert potential range for aluminum-doped zinc oxide (AZO).

<p>Electrochemical activity and inert potential range for aluminum-doped zinc oxide (AZO).</p

Potential range in which each substrate is inert for all electrolytes.

<p>Chemical stability is indicated by the color of the trace.</p

Electrochemical activity and inert potential range for highly oriented pyrolytic graphite (HOPG).

<p>Electrochemical activity and inert potential range for highly oriented pyrolytic graphite (HOPG).</p