Scrutinizing the redox activity of MOF-derived Fe-Se-C and P@Fe-Se-C species to improve overall water electrolysis and alkaline zinc-air batteries

Abstract

Versatile electrocatalysts made from earth-rich elements are essential for the design of energy storage and conversion devices such as those involved in electrolytic water splitting and zinc-air batteries. In this research, MOF-derived rod-like Fe-Se-C and P@Fe-Se-C nanocatalysts were applied to modify various active species on catalytic structures. TEM, XRD, XPS, and XAS characterizations of the MOF nanorod scaffold indicated a high abundance of catalytically-active species, including P@Fe-Se-C composite encased in Se on a carbon layer. High dual-functional activity of OER with η10 = 370 mV and ORR E1/2 = 0.77 V, similar to those of commercial IrO2 and Pt/C, was seen for Fe-Se-C. Additionally, the HER activity of the P@Fe-Se-C catalyst was η10 = 211 mV. In addition, Zn-air batteries (ZABs) exhibited better charge discharge cycle stability and an ideal stable open-circuit voltage of 1.58 V (P@Fe-Se-C). For overall water electrolysis, though, an optimal cell voltage of 1.43 V (P@Fe-Se-C) achieved a current density of 10 mA cm−2. According to DFT, there was important change in the electrocatalytic activity of P@Fe-Se-C and Fe-Se-C and the electronic structure, conductivity, and cyclic stability of the catalyst over time. This study shows how creative material design can improve energy efficiency and provide multifunctionality.