Ultrathin and Edge-Enriched Holey Nitride Nanosheets as Bifunctional Electrocatalysts for the Oxygen and Hydrogen Evolution Reactions

Abstract

Exploring economically efficient electrocatalysts with good electrocatalytic activity is essential for diverse electrochemical energy devices. Series of ultrathin metallic nickel-based holey nitride nanosheets were designed as bifunctional catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). They exhibit improved catalytic properties owing to the inherent advantages of their plentiful active reaction sites resulting from the complete exposure of the atoms in the large lateral surfaces and from the edges of pore areas, together with expanded lattice spacing distance. This obtained three-dimensional conductive integral architecture can not only accelerate the electron transportation by the highly orientated crystalline structure but also facilitate the diffusion of intermediate and gases. In terms of the OER electrocatalytic properties, a quite low overpotential (300 mV) is required for the holey two-dimensional (2D) Ni3Fe nitride nanosheets to deliver a current density of about 100 A g-1, with an enhanced improvement over IrO2by a factor of nearly 25 times. The holey 2D Ni3Fe nitride nanosheets also exhibit enhanced catalytic performance toward the HER, with a tiny overpotential (233 mV) to achieve a current density of about 100 A g-1with much better kinetic properties in comparison to those of highly active Pt/C.

Metallic‐State SnS2 Nanosheets with Expanded Lattice Spacing for High‐Performance Sodium‐Ion Batteries

“…[14,16,[18][19][20] However,t hese methods cannota ddress the electronic conductivity issues of SnS 2 semiconductors from am aterialp erspective.R ecently,t he approach of dopingm etal ions hasp rovenv ery fruitful and effective for improving the electrochemical performance by increasing the electronic conductivity and ion mobility.F or example, Se and Fe (or Co and Ni)c o-doped NbS 2 nanosheets showed significantly improved Li + /Na + storage properties compared with those of pure NbS 2 . [23][24][25][26][27] [22] However,t here are few studies devotedt oi nvestigating the role of the positiono fd oped metal ions in the lattice of ah ost materiala nd the related properties with respectt oc harged ensity redistribution, electron state density,a nd energy band structure.…”

Flexible Co–Mo–N/Au Electrodes with a Hierarchical Nanoporous Architecture as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction

“…In view of the thermodynamic instability of metal nitrides, surface oxidation occurs on the constituent CoMoN x nanosheets under the strongly oxidative environments of OER . This is attested by HRTEM characterization and XPS analysis of the constituent CoMoN x nanosheets after the initial OER measurement in 1 m KOH electrolyte.…”

“…The XPS survey of the constituent CoMoN x confirms the presence of N element in addition to Co and Mo from the precursor CoMoO 4 (Figure S3, Supporting Information). The N 1s XPS spectrum with the characteristic peak at 397.85 eV represents the formation of metal nitrides after the nitridation (Figure S4, Supporting Information) . Different from the Co 2+ and Mo 6+ oxidation states in the CoMoO 4 (Figure S5a,b, Supporting Information), high‐resolution XPS spectra of Co 2p and Mo 3d demonstrate that Co and Mo in the constituent CoMoN x exhibit evidently different chemical states (Figure 2c,d).…”

Nickel‐Based Transition Metal Nitride Electrocatalysts for the Oxygen Evolution Reaction

“…Notable reports here include work that began from research on the impact of the Co/N ratio in cobalt nitride catalysts. Other TMNs, such as NiCo 2 N( 180 mV overpotential,1 .32 Vo nset potential, 55 mV Ta fel slope), [53] NiMoN/CF (210 mV overpotential, 1.32 Vo nset potential, 55 mV Tafel slope), [54] and Ni 3 MnN (320 mV overpotential, 1.60 Vo nsetp otential, 64 mV Ta fel slope) [55] have also been studied for the OER. For example, Sun et al reported that it "further improved the OER activity in both neutral and alkaline solutions, with high stabilityi n3 0000 cycles".…”

“…Guo et al [55] synthesized ultrathin holey 2D nickel-cobalt/manganese/iron nitride nanosheets (below 1nmt hickness) by ammonolysis of the corresponding hydroxide precursors without using any support material (Figure 5g-i and Ta ble3). Owing to the large lattice spacing, highly oriented crystalline structural design copiously exposed catalytic active sites resultingb oth from the region near the boundaries of produced holes and from large laterals urfaces, which facilitatet ransitional transportation of reaction products and diffusion of the produced gases.…”