Unravelling the Bi‐Functional Electrocatalytic Properties of {Mo<sub>72</sub>Fe<sub>30</sub>} Polyoxometalate Nanostructures for Overall Water Splitting Using Scanning Electrochemical Microscope and Electrochemical Gating Methods
Karthikeyan Krishnamoorthy, Parthiban Pazhamalai, R. Swaminathan, Vigneshwaran Mohan, Sang‐Jae Kim
Abstract
Abstract This study reports the use of Keplerate‐type {Mo 72 Fe 30 } polyoxometalate (POMs) nanostructures as a bi‐functional‐electrocatalyst for HER and OER in an alkaline medium with a lower overpotential (135 mV for HER and 264 mV for OER), and excellent electrochemical stability. The bi‐functional catalytic properties of {Mo 72 Fe 30 } POM are studied using a scanning electrochemical microscope (SECM) via current mapping using substrate generation and tip collection mode. Furthermore, the bipolar nature of the {Mo 72 Fe 30 } POM nano‐electrocatalysts is studied using the electrochemical gating via simultaneous monitoring of the electrochemical (cell) and electrical ({Mo 72 Fe 30 } POM) signals. Next, a prototype water electrolyzer fabricated using {Mo 72 Fe 30 } POM electrocatalysts showed they can drive 10 mA cm −2 with a low cell voltage of 1.62 V in lab‐scale test conditions. Notably, the {Mo 72 Fe 30 } POM electrolyzers’ performance assessment based on recommended conditions for industrial aspects shows that they require a very low overpotential of 1.89 V to drive 500 mA cm −2 , highlighting their promising candidature toward clean‐hydrogen production.