• Duraisamy, Velu
• Wang, Yucheng
• Kumar, Sakkarapalayam Murugesan Senthil
• Venkateshwaran, Selvaraj
• Selvakumar, Karuppiah
• Arumugam, Natarajan
• Almansour Abdulrahman, I.
• Liu, Terence

Abstract

Manganese oxides (MnO 2 ) with nanowire morphology materials are a promising candidate for improving oxygen evolution and oxygen reduction reaction (OER/ORR) performance. In this work, we developed transition metal cation doping strategy into the α-MnO 2 tunnel structure to tune the Mn oxidation states and control the uniform nanowire morphology, crystalline structure in order to investigate the effect of doping over bifunctional activity. The single Ni 2+ cation doping in α-MnO 2 with various loading concentrations resulted in 8Ni-MnO 2 exhibiting remarkable OER and ORR activity owing to their excessive concentration of Mn 3+ and Mn 4+ octahedral sites respectively. Further, Co 2+ cation doping in 8Ni-MnO 2 leads to an enhanced synergistic effect that significantly improves the fraction of Mn 3+ quantity which is confirmed by average oxidation state. For, electrochemical OER performance of 8Co-8Ni-MnO 2 exhibits a potential of 1.77 V, Tafel slope value of 68 mV dec -1 and lower charge transfer resistance and it is active in ORR with more positive onset potential of 0.90 V, half-wave potential of 0.80 V, better current density (4.7 mA cm -2 ) and a four-electron pathway. Moreover, bifunctional activity (ΔE = E OER @10 mA cm -2 – ORR@E 1/2 ) of 8Co-8Ni-MnO 2 demonstrated 0.97 V, indicates an excellent activity in alkaline electrolyte solution.

Topics

• density
• impedance spectroscopy
• morphology
• Oxygen
• current density
• Manganese