Rugae-like FeP nanocrystal assembly on a carbon cloth: an exceptionally efficient and stable cathode for hydrogen evolution

Abstract

There is a strong demand to replace expensive Pt catalysts with cheap metal sulfides or phosphides for hydrogen generation in water electrolysis. Earth-abundant Fe can be electroplated on carbon cloth (CC) to form high surface area rugae-like FeOOH assembly. Subsequent gas phase phosphidation converts the FeOOH to FeP or FeP2 and the morphology of the crystal assembly is controlled by the phosphidation temperature. FeP prepared at 250 °C presents lower crystallinity and that prepared at higher temperatures of 400 °C and 500 °C possesses higher crystallinity, but lower surface area. The phosphidation at 300 °C produces nanocrystalline FeP and preserves the high-surface area morphology; thus, it exhibits the highest HER efficiency in 0.5 M H2SO4, i.e., the required overpotential to reach 10 and 20 mA cm(-2) is 34 and 43 mV, respectively. These values are lowest among the reported non-precious metal phosphides on CC. The Tafel slope for FeP prepared at 300 °C is around 29.2 mV dec(-1), which is comparable to that of Pt/CC; this indicates that the hydrogen evolution for our best FeP is limited by the Tafel reaction (same as Pt). Importantly, the FeP/CC catalyst exhibits much better stability in a wide-range working current density (up to 1 V cm(-2)), suggesting that it is a promising replacement of Pt for HER.

MOF‐Derived Bifunctional Iron Oxide and Iron Phosphide Nanoarchitecture Photoelectrode for Neutral Water Splitting

“…Very recently, Oh and co-workers found the presence of a small amount of a-Fe and Fe 3 C along with g-Fe 2 O 3 in the PXRD patterns during the pyrolysis of Fe-MIL-88A MOF. [43] A previous literature survey reported the same observed phenomenon when porous CoÀP/NC nano-polyhedrons composed of CoP x (a mixture of CoP and Co 2 P) nanoparticles were synthesized by solid-state phosphidation of Co 3 O 4 ÀNC. 01-078-1443 and 89-2261).…”

Well dispersed Fe2N nanoparticles on surface of nitrogen-doped reduced graphite oxide for highly efficient electrochemical hydrogen evolution

“…So, they have been identified as promising materials for catalyzing the HER. [9][10][11][12] Furthermore, iron nitride is regarded as the most promised candidate because of it's facile preparation and excellent chemical stability. 13 There also have some works about the catalytic activities of iron nitride-based materials with different structure and composition.…”

The hierarchical nanowires array of iron phosphide integrated on a carbon fiber paper as an effective electrocatalyst for hydrogen generation

“…In water splitting devices the HER catalysts are usually assembled into electrodes, and the performance of macroscopic electrodes is correlated both with the intrinsic catalytic activity of the HER catalysts and the rate of electron transport in the electrodes. 20,28,29 An advanced electrode structure, which offers sufficient surface active sites to catalyze the HER and enables fast internal electron transport, is beneficial for effective hydrogen generation. In most publications, nanoscopic catalysts (possibly with conductive additives to accelerate the electron transport in the electrode) are assembled into electrode with the aid of binding agent (e.g.…”

“…carbon fiber paper, Ti foil, and etc) have demonstrated superior performance in comparison with the electrode assembled randomly by the nanostructure of the HER catalyst. 20,28,30,31 This configuration offers the shortest path length of electron transport, and enables fast electron transport in the electrode. Though the configuration is promising, the morphology of nanostructures in this configuration is limited in nanowire 20,30 or nanosheet.…”