Flexible and Binder-Free Iron Phosphide Electrodes Using a Three-Dimensional Support for High Hydrogen Productivity

In this work, an inexpensive and reliable microstructured electrode for the hydrogen evolution reaction (HER) is developed. This cathode is made of Earth-abundant elements consisting of iron phosphide as an electrocatalyst and carbon felt (CF) as a flexible conductive scaffold. Its porous character and binder-free FeP coverage over the carbon fibers generate a high number of accessible active sites for the reaction, achieving a high value of the electrochemically active surface area. The electrode reaches 100 mA center dot cm(-2) by applying only 53 mV vs RHE at 50 degrees C in 0.5 M H2SO4, demonstrating excellent electrocatalytic activity for the HER and outstanding stability in acidic electrolyte. Furthermore, the feasibility of these electrodes for industrial application is evaluated using a PEM electrolyzer. The developed prototype with a cathodic area of 1.8 cm(2) shows a very promising performance, reaching 14.9 mmol H-2 center dot h(-1) center dot cm(-2) (corresponding to 800 mA center dot cm(-2)) at a voltage of only 2.1 V.

Automated summary

In this work, a low-cost and reliable microstructured electrode for the hydrogen evolution reaction is developed. The electrode consists of iron phosphide as an electrocatalyst and carbon felt as a flexible conductive scaffold. It demonstrates excellent electrocatalytic activity and stability in acidic electrolyte, achieving high values of electrochemically active surface area and current density. Furthermore, the feasibility of using these electrodes for industrial applications is evaluated, showing promising performance in a PEM electrolyzer with high hydrogen production rate at a low voltage.