A novel particle-in-nanoplate architecture of iron nickel phosphide intertwined with carbon nanotubes for efficient water oxidation and high-performance sodium-ion batteries

Abstract The oxygen evolution reaction (OER) with sluggish kinetics is considered the bottleneck for developing clean and efficient H 2 production from electrochemical water splitting. Exploring a high-efficient and good durability OER electrocatalyst to promote the reaction rate has drawn enormous attention. Herein, a particle-in-nanoplate architecture constructed by self-assembled Ni 2.3 FeP 3.4 nanoparticles intertwined with the carbon nanotubes (Ni 2.3 FeP 3.4 /CNTs) is synthesized. The architecture of the resultant novel electrocatalyst Ni 2.3 FeP 3.4 /CNTs, which possesses the optimal balance of electrochemical active site, ion and electron conductivity, phosphorous content, delivers highly effective and stable electrocatalytic performance. In detail, as for OER, the Ni 2.3 FeP 3.4 /CNTs exhibits extraordinarily high-efficient with the smallest onset potential of ∼1.43 V vs. RHE, the lowest over-potential of 239 mV and 282 mV to reach the current densities of 10 and 100 mA cm −2 , respectively, and the smallest Tafel slopes of 26.9 mV dec −1 in 1 M KOH. During 12 h galvanostatic electrolysis, the voltage is well maintained without any significant increase, representing a stable non-precious-metal catalyst for water oxidation. Moreover, a lower cell voltage of 1.523 V is achieved at a current density of 10 mA cm −2  by using it as a cathode in the overall water splitting. In addition, for the first time, the Ni 2.3 FeP 3.4 /CNTs is designed as an anode material for sodium ion batteries (SIBs). Consequently, the as-prepared Ni 2.3 FeP 3.4 /CNTs nanoarchitecture shows a high reversible capacity of 335.1 mAh g −1 at 100 mA g −1 , excellent rate capability of 58.3 mA h g −1 under 10 A g −1 , and stable long-term cycling performance.