Medium‐Entropy Metal Selenides Nanoparticles with Optimized Electronic Structure as High‐Performance Bifunctional Electrocatalysts for Overall Water Splitting

Abstract

Development of low-cost and high-efficiency electrocatalysts for overall water splitting is of great significance in the sustainable hydrogen economy. Herein, Fe 1.2 (CoNi) 1.8 Se x medium-entropy metal selenides (MESes) nanoparticles are prepared via the selenylation of metal-organic frameworks (MOFs) precursors. The optimal Fe 1.2 (CoNi) 1.8 Se 6 MESe exhibits an outstanding electrocatalytic performance in alkaline media, offering low overpotentials of 66 and 216 mV at 10 mA cm −2 for the hydrogen evolution reaction and oxygen evolution reaction, respectively. A full electrolysis apparatus with Fe 1.2 (CoNi) 1.8 Se 6 MESe as both cathode and anode displays an excellent performance, achieving 10 mA cm −2 at a potential of 1.55 V. Furthermore, density functional theory calculations demonstrate that the formation of MESe enhances the surface charge density and brings the d-band center closer to Fermi level, as compared with that of the MOF precursor. Overall, the proposed strategy of medium-entropy materials presents a low-cost approach to fabricate energy storage and conversion devices.

Constructing a medium-entropy spinel oxide FeNiMnO4/CeO2 heterojunction as a high-performance electrocatalyst for the oxygen evolution reaction

“…It has been observed that the transfer of electrons on the surface of the FeNiMnO 4 /CeO 2 heterojunction is more pronounced than that on FeNiMnO 4 , which facilitates bond activation. 67,68 Fig. 5c illustrates the two-dimensional plane charge density difference (Δ ρ ) that was obtained to provide a more intuitive understanding of the charge transfer process.…”

Current progress in metal–organic frameworks and their derivatives for electrocatalytic water splitting

“…4d). 100 The best Fe 1.2 (CoNi) 1.8 Se 6 showed excellent electrocatalytic properties in alkaline media. Compared with MOF precursors, the formation of medium-entropy nanoparticles increased the surface charge density and brought the D-band center closer to the Fermi level.…”

Medium-Entropy Co–Fe–Cr–Mo Spinel Nanoflowers as Electrocatalysts for Oxygen Evolution

“…Wu et al prepared Fe 1.2 (CoNi) 1.8 Se x MEM using the solvothermal method. 28 29 Therefore, medium-entropy catalysts can combine the benefits of each element and demonstrate remarkable catalytic performance. Unlike powder catalysts that need to be fixed on electrodes using binders, self-supporting electrocatalytic materials are directly grown on conductive substrates without the need for binders, thus avoiding the problems of the blockage of catalytically active sites aroused by the binders and the exfoliation from the electrodes.…”

“…The electrons tend to be enriched in Fe-dominated metal sites after the introduction of C/N, leading to excellent OER activity due to the weakened adsorption of the electron-rich metal sites. Wu et al prepared Fe 1.2 (CoNi) 1.8 Se x MEM using the solvothermal method . DFT calculations indicated that the center of the d-band of the metal was approaching the Fermi level, which effectively enhanced the adsorption and desorption of *H on the catalyst surface, thus reducing the Gibbs free energy.…”