Temperature-controlled fabrication of Co-Fe-based nanoframes for efficient oxygen evolution

Abstract

Transition metal phosphides (TMPs) have emerged as promising electrocatalysts to enhance the slow kinetic process of oxygen evolution reaction (OER). Framelike hollow nanostructures (nanoframes, NFs) provide the open structure with more accessible active sites and sufficient channels into the interior volume. Here, we report the fabrication of bimetallic Co-Fe phosphide NFs (Co-Fe-P NFs) via an intriguing temperature-controlled strategy for the preparation of precursors followed by phosphidation. The precursors, Co-Fe Prussian blue analogues (Co-Fe PBAs) are prepared by a precipitation method with Co 2+ and [Fe(CN) 6 ] 3− , which experience a structural conversion from nanocubes to NFs by increasing the aging temperature from 5 to 35°C. The experimental results indicate that this conversion is attributable to the preferentially epitaxial growth on the edges and corners of nanocubes, triggered by intramolecular electron transfer at an elevated aging temperature. The as-prepared Co-Fe-P NFs catalyst shows remarkable catalytic activity toward OER with a low overpotential of 276 mV to obtain a current density of 10 mA cm −2 , which is superior to the reference samples (Co-Fe-P nanocubes) and most of the recently reported TMPs-based electrocatalysts. The synthetic strategy can be extended to fabricate Co-Fe dichalcogenide NFs, thereby holding a great promise for the broad applications in energy storage and conversion systems.

Amorphous-crystalline PdRu bimetallene for efficient hydrogen evolution electrocatalysis

“…The high-resolution TEM (HRTEM) image and corresponding fast Fourier transform (FFT) patterns demonstrate the co-existence of crystallization and amorphous regions, which mainly is ascribed to the fact that the low reaction temperature and fast reaction rate result in rapid nucleation and crystallization. 19,26,27 The amorphous-crystalline heterophase structure can accelerate electron/mass transfer, which is favorable to the HER performance. The high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) image of PdRu bimetallene exhibits a lateral size of about 450 nm (Fig.…”

“…16,17 Heterophase engineering, in particular, the formation of an amorphous-crystalline heterophase, is an attractive approach to enhance electrocatalytic activity due to unique physicochemical properties. 18,19 However, strong metallic bonds of noble metals cause difficulty in the preparation of amorphous noble metal electrocatalysts. In addition, alloying Pd with other metals is also an indispensable strategy to improve catalytic performance, which can adjust the electronic and geometric structure and thus optimize the hydrogen adsorption energy on catalysts.…”

FeP-CoP Nanocubes In Situ Grown on Ti3C2Tx MXene as Efficient Electrocatalysts for the Oxygen Evolution Reaction

“…While the second one at 710.40 and 723.90 eV corresponds to Fe 3+ 2p 3/2 and 2p 1/2 , which results from the inevitable surface oxidation of Fe in the air. 37,38 Analogously, the high-resolution spectra of Co 2p reveal three doublets (Figure 3b). The peaks at 778.36 and 793.26 eV are assigned to the Co 2+ 2p 3/2 and 2p 1/2 of Co−P bonds, and the peaks with binding energies of 781.57 and 797.57 eV are attributed to the oxidized Co 3+ species owing to the surface oxidation.…”

Development of a Hemispherical Cavity Cobalt Electrocatalyst for Water Oxidation Based on a Polystyrene Colloidal Template Electrodeposition Method

“…[33] Meanwhile, Wu and colleagues developed Co 3 O 4 nanowires on a Ti substrate as Li ion batteries by chemical vapor deposition. [34] In addition, Chen et al also are reporting about nanoframe electrocatalysts composed of Co-Fe, [35] CoP, [36] and Ni 2 P-Co 2 P [37] by using prussian blue analogues as precursors in the nanomaterials. Therefore, these approaches are expected to improve the electrochemical properties and catalytic activity by increasing the surface area of the catalyst.…”