Fabrication of Nickel–Cobalt Bimetal Phosphide Nanocages for Enhanced Oxygen Evolution Catalysis

Abstract

Replacement of precious metals with earth‐abundant electrocatalysts for oxygen evolution reaction (OER) holds great promise for realizing practically viable water‐splitting systems. It still remains a great challenge to develop low‐cost, highly efficient, and durable OER catalysts. Here, the composition and morphology of Ni–Co bimetal phosphide nanocages are engineered for a highly efficient and durable OER electrocatalyst. The nanocage structure enlarges the effective specific area and facilitates the contact between catalyst and electrolyte. The as‐prepared Ni–Co bimetal phosphide nanocages show superior OER performance compared with Ni2P and CoP nanocages. By controlling the molar ratio of Ni/Co atoms in Ni–Co bimetal hydroxides, the Ni0.6Co1.4P nanocages derived from Ni0.6Co1.4(OH)2 nanocages exhibit remarkable OER catalytic activity (η = 300 mV at 10 mA cm−2) and long‐term stability (10 h for continuous test). The density‐functional‐theory calculations suggest that the appropriate Co doping concentration increases density of states at the Fermi level and makes the d‐states more close to Fermi level, giving rise to high charge carrier density and low intermedia adsorption energy than those of Ni2P and CoP. This work also provides a general approach to optimize the catalysis performance of bimetal compounds.

Vanadium Doped Nickel Phosphide Nanosheets Self‐Assembled Microspheres as a High‐Efficiency Oxygen Evolution Catalyst

“…As shown in the high-resolution spectrum of Ni 2p in Figure 3a, the spectrum can be deconvoluted into six peaks. The two main peaks at 857.1 and 874.9 eV can be attributed to Ni 2p 3/2 and Ni 2p 1/2 , along with two satellite peaks at 861.4 and 880.3 eV, [37] respectively. What's more, the two peaks located at 857.1 and 874.9 eV can also be assigned to Ni 3 + and Ni 2 + species, respectively.…”

“…The high‐resolution spectrum of P 2p in Figure c shows that two peaks located at 129.5 and 130.5 eV are assigned to the P 2p 3/2 and P 2p 1/2 , respectively and well matched to the P 3− , indicating the formation of metal phosphides. The peaks at 134.5 eV illustrate the generation of P−O bonds owing to the sample's oxidation in air . The high‐resolution spectrum of O 1s in Figure d can be deconvoluted into two main peaks located at 531.7 and 533.3 eV, which can be ascribed to the adsorbed oxygen/O−H species and P−O components, respectively .…”

Phosphorus Incorporation into Co9S8 Nanocages for Highly Efficient Oxygen Evolution Catalysis

“…Unfortunately, the high overpotential to drive the reaction significantly reduces the conversion efficiency of water splitting. Furthermore, it is difficult to fabricate these precious metal catalysts in mass production owing to their high cost and low elemental abundance . To solve these problems, considerable efforts have been devoted to explore low‐overpotential, stable and earth‐abundant OER catalysts.…”

Octahedral Cu2O@Co(OH)2 Nanocages with Hierarchical Flake‐Like Walls and Yolk‐Shell Structures for Enhanced Electrocatalytic Activity

“…Notably, the octahedral inner core and void space can be explicitly observed through the broken nanocages, revealing the formation of yolk‐shell structure. In addition, the shell structure shows flak‐like morphology, generally endowing these nanocages with large surface area and abundant active sites . As compared to the XRD pattern of Cu 2 O precursor, no other obvious diffraction peaks are observed in that of Cu 2 O@Co(OH) 2 nanocages (Figure S2), suggesting the amorphous nature of Co(OH) 2 shell .…”