Cr‐Doped FeNi–P Nanoparticles Encapsulated into N‐Doped Carbon Nanotube as a Robust Bifunctional Catalyst for Efficient Overall Water Splitting

Abstract

Exploring high‐efficiency, stable, and cost‐effective bifunctional electrocatalysts for overall water splitting is greatly desirable and challenging. Herein, a newly designed hybrid catalyst with Cr‐doped FeNi–P nanoparticles encapsulated into N‐doped carbon nanotubes (Cr‐doped FeNi–P/NCN) with unprecedented electrocatalytic activity is developed by a simple one‐step heating treatment. The as‐synthesized Cr‐doped FeNi–P/NCN with moderate Cr doping exhibits admirable oxygen evolution reaction and hydrogen evolution reaction activities with overpotentials of 240 and 190 mV to reach a current density of 10 mA cm−2 in 1 m KOH solution. When used in overall water splitting as a bifunctional catalyst, it needs only 1.50 V to give a current density of 10 mA cm−2, which is superior to its typically integrated Pt/C and RuO2 counterparts (1.54 V @ 10 mA cm−2). Density functional theory calculation confirms that Cr doping into a FeNi‐host can effectively alter the relative Gibbs adsorption energy and reduces the theoretical overpotential. Additionally, the synergetic effects between Cr‐doped FeNi–P nanoparticles and NCNs are regarded as significant contributors to accelerate charge transfer and promote electrocatalytic activity in hybrid catalysts.

Multifunctional Transition Metal‐Based Phosphides in Energy‐Related Electrocatalysis

“…As expected, 8.3% Zn doped CoP showed promoted HER activity with merely requiring 39 mV overpotential to drive a current density of 10 mA cm −2 , which was better than that of pristine CoP (82 mV), Zn 0.04 Co 0.96 P (46 mV) and Zn 0.13 Co 0.87 P (66 mV) (Figure c). Beyond Zn, elements of Mn, V, Ce, Cu, Cr were successively recognized as good dopants . The enhanced performance was ascribed to the enhanced electron interaction and optimized Δ G H* .…”

Natural‐Cellulose‐Nanofibril‐Tailored NiFe Nanoparticles for Efficient Oxygen Evolution Reaction

“…The oxygen evolution reaction (OER), is an important reaction in water splitting to produce sustainable hydrogen, and is also involved with metal‐air batteries, solar cells, and fuel cells . However, OER has become a major obstacle for water splitting due to its sluggish kinetics, as it involves the processes of O−H band breaking, O−O bond combination, and multiple electron transfer . Therefore, the OER process usually requires a high overpotential and displays low efficiency.…”

“…Although precious metal oxides, such as IrO 2 and RuO 2 , are the high‐performance OER catalysts, but their scarcity and high cost impede their practical applications . Therefore, designing highly active catalysts with low overpotentials and high efficiency toward the OER with abundant resources is greatly favorable …”

“…[1,2] However, OER has become a major obstacle for water splitting due to its sluggish kinetics, as it involves the processes of OÀ H band breaking, OÀ O bond combination, and multiple electron transfer. [3,4] Therefore, the OER process usually requires a high overpotential and displays low efficiency. Thus, efficient catalysts are desirable to decrease the overpotential and improve the OER activity.…”

“…[5] Therefore, designing highly active catalysts with low overpotentials and high efficiency toward the OER with abundant resources is greatly favorable. [4,6] Considerable efforts have therefore been devoted to developing non-precious metal catalysts for OER. [7,8] In particular, transition metal (such as Fe, Co, and Ni) sulfides, nitrides, phosphides, borides, hydro(oxy)oxides have been proved to be promising OER catalysts.…”