Search

Cobalt phosphide (CoP) is a promising electrocatalyst due to its abundance and excellent stability in alkaline solution. However, its poor conductivity and intrinsic catalytic activity limit its potential in electrochemical water splitting. To address this, a heterogeneous atom doping strategy has been proposed to synthesize magnesium-doped cobalt phosphide nanoneedle arrays, or Mg-doped CoP. Our theoretical calculations show that transition metal Mg atoms doping into the CoP lattice can enhance the electronic structure and modulate the free energy of reacting species, resulting in a significant improvement in the intrinsic catalytic activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) process. The electrochemical tests reveal that the optimal 10% Mg-doped CoP nanoneedle arrays exhibit outstanding HER and OER electrocatalytic activities with overpotential values of 85 and 236 mV at 10 mA/cm2, respectively, outperforming previously reported CoP-based catalysts. This study not only presents a strategy to enhance the catalytic activity of CoP-based materials, but also offers a reference for achieving efficient electrochemical hydrogen production by hydrolysis. [Display omitted] • The charge compensation effect optimizes not only the electronic structure but also the free energy of H∗ and HOO∗ species. • The low-valent Mg2+ ions replace part of the Co3+ sites in the CoP lattice. • The creation of phosphorus vacancies in adjacent sites to maintain electroneutrality. [ABSTRACT FROM AUTHOR]

In this paper, the N-doped graphene nanotubes (N-GNTs) are used as the scaffolds to grow α-Fe 2 O 3 nanoparticles (NPs) and Ni(OH) 2 nanosheets arrays (NAs)/Co 0.85 Se nanoparticles (NPs) respectively, which are directly acted as hybrid negative and positive electrodes for alkaline rechargeable battery (ARB). The synergistic merits from the supporters and active materials enable the N-GNTs@ α-Fe 2 O 3 NPs to deliver an ultrahigh specific capacity of 309 mAh g−1 at 1 A g−1, and good rate performance. By paring with the N-GNTs@ Ni(OH) 2 NAs/Co 0.85 Se NPs (268 mAh g−1 at 1 A g−1), an ARB configuration is assembled. Contributed by the particular electrode architectures, the device displays a high energy density of 78.8 Wh kg−1 at 2.47 kW kg−1 and robust cycling life (91.3% retention of the initial specific capacity over 10,000 cycles). This strategy reported here opens up a new avenue to construct unique hybrid electrodes and maximizes their superiority, which leads to the ultrahigh capacity for the fabrication of next-generation energy storage devices. • The two advanced hybrid electrode materials were prepared respectively. • The electrodes show ultrahigh specific capacity and good rate performance. • An alkaline rechargeable battery with the two electrodes was successfully assembled. • The device can present high energy density and outstanding cycling performance. [ABSTRACT FROM AUTHOR]