Cobalt Phosphide Composite Encapsulated within N,P‐Doped Carbon Nanotubes for Synergistic Oxygen Evolution

Abstract

Exploring highly efficient and stable oxygen evolution reaction (OER) electrocatalysts such as transition-metal phosphides (TMPs) is critical to advancing renewable hydrogen fuel. TMP nanostructures typically involving binary or ternary TMPs tuned by cation or anion doping are suggested to be promising low-cost and durable OER catalysts. Herein, the preparation of CoP/CoP composite nanoparticles encapsulated within N,P-doped carbon nanotubes (CoP/CoP @NPCNTs) is demonstrated as a synergistic electrocatalyst for OER via the calcination of a CoAl-layered double hydroxide/melamine mixture and subsequent phosphorization. Facile visualization by scanning electron microscopy in conjunction with electron backscatter diffraction demonstrates the encapsulation of the CoP/CoP nanoparticles within the N,P-codoped CNTs. Electrocatalytic evaluation shows that the composite electrode requires a low overpotential of 300 mV for the OER at 10 mA cm in a 1.0 m KOH solution and, in particular, exhibits an excellent long-term durability of ≈100 h, which is superior to that of the state-of-the-art RuO electrocatalyst. Density functional theory calculations reveal that the synergistic effect of CoP and CoP can enhance the electrocatalytic performance. In addition, molecular dynamics simulations demonstrate that the generated O molecules can readily diffuse out of the CNTs. Both the effects give rise to the observed OER enhancement.

Co/CoP Nanoparticles Encapsulated Within N, P-Doped Carbon Nanotubes on Nanoporous Metal-Organic Framework Nanosheets for Oxygen Reduction and Oxygen Evolution Reactions

“…The peaks centralized at 778.9 eV and 793.9 eV are associated with Co 3+ , other peaks were centered at 781.6 eV and 797.5 eV are connected to Co 2+ . In addition, the strong satellite peaks centered on 786.2 and 803 eV are attributed to the vibration of Co 3+ [21,[49][50][51]. As shown in Fig.…”

Cobalt Phosphides Nanocrystals Encapsulated by P‐Doped Carbon and Married with P‐Doped Graphene for Overall Water Splitting

“…In addition, Lou and co‐workers fabricated Ni‐Co mixed metal phosphide and amorphous carbon (NiCoP/C) nanoboxes, showing enhanced electrocatalytic performance relative to pure NiCoP and Ni‐Co‐LDH nanobox . Moreover, Xu et al prepared CoP/CoP 2 nanoparticles and N,P‐doped carbon nanotubes NHs, which exhibited enhanced catalytic activity ascribed to the synergistic effect of CoP 2 and CoP and the easy diffusion of formed O 2 from N,P‐doped carbon nanotubes . Those outstanding works confirm that adopting multiple strategies to fabricate complex TMPs based NHs can well tune the electronic structure of desired TMPs and facilitate to boost their electrocatalytic properties for OWS.…”

Carbon‐Enriched Cobalt Phosphide with Assorted Nanostructure as a Multifunctional Electrode for Energy Conversion and Storage Devices

“…(iii) The HER catalytic nature of the Co 2 P can be correlated with the unique charged natures of Co and P species. The small positive and negative charges on Co δ+ and P δ− respectively has transformed it as hydride acceptor and proton acceptor sites in Co 2 P to enhance the HER catalytic activity of the compound . (iv) Furthermore, the unique assorted morphology has enhanced the accessibility of electrolyte and enables the incidence of bounteous ions on the electrode surface.…”

“…Phosphides with its metalloid property combine with cobalt resembling a submetallic alloy, which possesses much higher intrinsic conductivity that induces bouncing kinetic rate overpowering the oxides. This empowers the fast electron transfer rate between the electrode and electrolyte that generates improved energy density in supercapacitors and upgraded catalytic activity for electrocatalysts . Moreover, cobalt phosphide as an electrode appears to be more robust related to sulphide electrode due to its resilient durability in high alkaline electrolytes, whereas the sulphide based electrode has a tendency to decompose profoundly dropping its initial capacity.…”