Hierarchical FeNiP@Ultrathin Carbon Nanoflakes as Alkaline Oxygen Evolution and Acidic Hydrogen Evolution Catalyst for Efficient Water Electrolysis and Organic Decomposition

Abstract

Efficiency of hydrogen evolution via water electrolysis is mainly impeded by the kinetically sluggish oxygen evolution reaction (OER). Thus, it is of great significance to develop highly active and stable OER catalyst for alkaline water electrolysis or to substitute the more kinetically demanding acidic OER with a facile electron-donating reaction such that OER is no longer the bottleneck half-reaction for either acidic or alkaline water electrolysis. Herein, the hierarchical Fe-Ni phosphide shelled with ultrathin carbon networks on Ni foam (FeNiP@C) is reported and shows exceptional OER activity and enhanced chemical stability in 1 M KOH. This unique electrode provides large active sites, facile electron transport pathways, and rapid gas release, resulting in a remarkable OER activity that delivers a current density of 100 mA/cm at an overpotential of 182 mV with a Tafel slope of 56 mV/dec. Combining the hydrogen evolution reaction with organic pollutant (methylene blue) oxidation, a multifunctional electrolyzer for simultaneous cost-effective hydrogen generation and organic pollutant decomposition in acid wastewater is proposed. Our strategies in this work provide attractive opportunities in energy- and environment-related fields.

Three‐Dimensional Graphene‐Foam‐Supported Hierarchical Nickel Iron Phosphide Nanosheet Arrays as Efficient and Stable Bifunctional Electrocatalysts for Overall Water Splitting

“…The nanosheets structure of NiFe‐P@3DGF was further confirmed by transmission electron microscopy (TEM). The morphology of NiFe‐P nanosheets (Figure e) obtained by high angle annular dark field scanning TEM (HAADF‐STEM) shows that there are many pores on the nanosheets, which is due to the release of gas during the phosphating process . From the high‐resolution TEM (HRTEM) image (Figure f), the lattice fringe spacing is 0.228 nm, which is slightly larger than Ni 2 P (0.226 nm), attributed to the replacement of Ni atom by Fe atom with larger radius in NiFe‐P@3DGF.…”

“…The morphology of NiFe-P nanosheets (Figure 2e) obtained by high angle annular dark field scanning TEM (HAADF-STEM) shows that there are many pores on the nanosheets, which is due to the release of gas during the phosphating process. [22,52] From the high-resolution TEM (HRTEM) image (Figure 2f), the lattice fringe spacing is 0.228 nm, which is slightly larger than Ni 2 P (0.226 nm), attributed to the replacement of Ni atom by Fe atom with larger radius in NiFe-P@3DGF. The coexistence of Ni, Fe and P can be confirmed from the energy-dispersive X-ray (EDX) spectrum ( Figure S7), with the atomic ratio of 43 : 22 : 35.…”

“…Among them, transition metal phosphides (TMPs) (M=Fe, Co, Ni, Cu, etc.) highlight due to their low price and impressive catalytic activity . Recently, the studies demonstrate that the element doping can regulate the local distribution of electron cloud density on the intermetallic compounds and improve charge transfer between host atoms and doping atoms, which could further lower the kinetic energy barriers in the catalytic processes and effectively promote the catalytic performances.…”

“…highlight due to their low price and impressive catalytic activity. [22][23][24][25] Recently, the studies demonstrate that the element doping can regulate the local distribution of electron cloud density on the intermetallic compounds and improve charge transfer between host atoms and doping atoms, which could further lower the kinetic energy barriers in the catalytic processes and effectively promote the catalytic performances. Therefore, the researchers have paid more attentions on adding another metal element to form a bimetal TMP and achieved some outstanding results.…”

Enhanced Interfacial Charge Transfer and Separation Rate based on Sub 10 nm MoS2 Nanoflakes In Situ Grown on Graphitic‐C3N4

“…The photocurrent densities of pristine MoS 2 , 2%, 4%, 6%, 8%, and 10% MoS 2 /g‐C 3 N 4 catalysts showed 0.19, 0.25, 0.34, 0.46, 0.75, and 0.68 µA cm −2 under the visible light irradiation, respectively. By comparison, the 8% MoS 2 /g‐C 3 N 4 photocatalyst exhibits the highest photocurrent density since the MoS 2 nanoflakes can provide more visible light absorption sites and boost the transfer rate of photoproduced charge carriers under the visible light irradiation . When the content of MoS 2 increases more than 10%, the photocurrent density is decreased, which is attributed to the negative effects of the excessive content of MoS 2 .…”