Boosting Alkaline Water Splitting Efficiency: NiOOH-MnOOH Heterojunctions via In Situ Anodic Oxidation

Abstract

Designing noble metal-free electrocatalysts remains a challenge for oxygen evolution reactions (OER) in alkaline solutions. In this study, we present a facile electrodeposition approach coupled with an in-situ anodic oxidation method to synthesize NiOOH-MnS/NF on nickel foam (NF), successfully creating NiOOH-MnOOH/NF heterojunctions to boost OER performance in alkaline conditions. The heterojunction's synergistic effect significantly modulates the adsorption energy of the rate-determining step (RDS), thereby enhancing the intrinsic electrocatalytic activity of the NiOOH-MnOOH/NF electrocatalyst. Furthermore, the introduction of SO42- leads to a variable degree of electron loss in both Mn and Ni, reducing adsorption strength for the OER intermediates and thus optimizing reaction kinetics. The as-prepared NiOOH-MnOOH/NF electrocatalyst demonstrates exceptional OER performance in 1.0 M KOH, achieving a current density of 100 mA cm-2 with a Tafel slope of 52.3 mV dec-1 and a minimal overpotential of 391 mV. Utilizing NiOOH-MnOOH/NF as a bifunctional electrode for overall water splitting (OWS), the system operates at a low potential of 1.66 V at 10 mA cm-2, showcasing its excellent durability. This work offers novel insights and promising prospects for the advancement and practical application of non-precious metal electrocatalysts in the field of electrocatalytic water splitting.