Precious Metal Containing Polyoxometalate Derived Electrocatalyst for Water Splitting at Reduced Precious Metal Usage

Abstract

Electrochemical water splitting offers a sustainable path to generate high-purity hydrogen, a cornerstone of the green energy transition. Among competing technologies, proton exchange membrane water electrolysis (PEMWE) stands out for its efficiency, safety, and compatibility with intermittent renewable energy sources. However, its large-scale implementation is limited by the need for highly stable and active catalysts in acidic environments. Precious metals like platinum (Pt), iridium (Ir), and ruthenium (Ru) provide excellent catalytic performance, but their high cost and scarcity necessitate strategies to minimize usage while retaining activity. This thesis explores recent innovations in PEMWE catalyst design aimed at reducing precious metal content and improving overall efficiency and durability.

A key focus is the development of a novel Pt-based catalyst (PtW₆Oₓ/C), synthesized from a Pt-containing heteropolyoxotungstate precursor. Ultrafast Joule-heating was employed to atomically anchor Pt onto defective tungsten oxide nanoislands supported on carbon, forming highly active single-Pt-atom sites. The resulting catalyst showed a 20-fold improvement in Pt mass-specific activity over commercial 20 wt% Pt/C and reached 3 A cm⁻² at 1.839 V in PEM electrolysis testing. Additionally, the thesis identifies RbSbWO₆ as a promising bifunctional metal oxide catalyst for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), through a methodology integrating data mining, surface state analysis, and microkinetic modeling. Experimental validation confirmed its durability and performance under acidic conditions, offering a cost-effective alternative to noble metals.

Overall, this research advances catalyst design for efficient and scalable water-splitting, contributing to the global shift toward clean hydrogen technologies.