Nitrogen and phosphorous co-doped carbon nanotubes embedded via active Ni2P nanoparticles as an advanced in-situ generated electrocatalyst for water oxidation

Abstract

• Ni 2 P NPs/N, P-CNT-850 prepared by a novel in-situ one-step carbonization strategy. • The optimized Ni 2 P NPs/N, P-CNT-850 electrocatalyst shows remarkable OER performance in the alkaline solution. • Electrocatalytic activity exceeds the benchmark RuO 2 electrocatalyst. • N,P co-doped CNTs can optimize the electronic structure to enhance electrocatalytic activity. • The enhanced performance resulted from the multicomponent synergetic effect. Earth-abundant nickel-based composites are of high concern as electrocatalysts for the oxygen evolution reaction (OER) which are significant to many sustainable chemical and energy transformation technologies. However, the realization of effective OER is still far away by the requirement of a high sustainable driving potential above thermodynamic requirements. In this work, we develop an innovative one-pot in-situ approach to synthesize nitrogen (N) and phosphorous (P) co-doped carbon nanotubes (CNTs) embedded with Ni 2 P nanoparticles. The structure of Ni 2 P nanoparticles in carbon nanotubes and their electrocatalytic activities have been studied in relation to varied carbonization temperatures. Benefiting from the in-situ designed Ni 2 P nanoparticles, N, P co-doped carbon nanotubes (NP-CNTs) with larger surface area, pore-rich structure, and optimized temperature, the as-prepared Ni 2 P NPs/NP-CNT-850 exhibits remarkable electrocatalytic activity for the OER in 1.0 M alkaline solution. In particular, the optimized Ni 2 P NPs/NP-CNT-850 can achieve a reference current density of 10 mA cm −2 at a very low overpotential of 298 mV and lower Tafel slope of 53 mV dec -1 . This electrocatalyst also shows long-term stability without significant degradation for 17 h. Our study opens innovative in-situ engineering to dramatically increase the electrocatalytic activity of Ni-based composite for other applications via rational design of architectures with multiple active sites.