Synergistically Enhanced Oxygen Evolution Catalysis with Surface Modified Halloysite Nanotube

Abstract

Synergistically increased oxygen evolution reaction (OER) of manganese oxide (MnO2) catalyst is introduced with surface-modified halloysite nanotube (Fe3 O4-HNTs) structure. The flake shaped MnO2 catalyst is attached on the nanotube template (Fe3 O4-HNTs) by series of wet chemical and hydrothermal method. The strong interaction between MnO2 and Fe3 O4-HNTs maximized active surface area and inter-connectivity for festinate charge transfer reaction for OER. The synergistical effect between Fe3 O4 layer and MnO2 catalyst enhance the Mn /Mn ratio by partial replacement of Mn ions with Fe. The relatively increased Mn3+Mn ratio4+ on MnO3+/ 4+2 @FHNTs induced σ∗orbital (eg) occupation close to single electron, improving the OER performances. The MnO2 @FHNTs catalyst exhibited the reduced overpotential of 0.42 V (E vs. RHE) at 10 mA/ cm and Tafel slope of (99 mV/dec), compared with that of MnO22 with unmodified HNTs (0.65 V, 219 mV/dec) and pris-tine MnO2 (0.53 V, 205 mV/dec). The present study provides simple and innovative method to fabricate nano fiberized OER catalyst for a broad application of energy conversion and storage systems.