Isopropanol Electro-Oxidation on PtCu Alloys for Aqueous Organic Redox Chemistry Toward Energy Storage

TL;DR

This paper explores using isopropanol and PtCu alloys in redox flow batteries for efficient and low-cost energy storage.

Contribution

The study introduces PtCu alloys as effective electrocatalysts for isopropanol electro-oxidation in aqueous-organic redox flow batteries.

Findings

PtCu catalysts achieved a low activation energy of 14.4 kJ/mol for isopropanol electro-oxidation.

PtCu showed enhanced resistance to catalyst poisoning compared to pure Pt.

A PtCu-catalyzed H-cell demonstrated stable cycling over 200 cycles.

Abstract

Integration of renewable energy into modern power grids remains limited by intermittency and the need for reliable energy storage. Redox flow batteries (RFBs) are promising for large-scale energy storage, yet their widespread adoption is hindered by the high cost. In this study, we investigate isopropanol as a redox-active species with Pt-Cu alloy electrocatalysts for aqueous-organic RFBs. A series of PtxCu catalysts with varying Pt:Cu ratios were synthesized and studied for isopropanol electro-oxidation reaction (IPAOR) performance. Among them, PtCu demonstrated the best performance, achieving a low activation energy of 14.4 kJ/mol at 0.45 V vs. RHE and excellent stability at 1 M isopropanol (IPA) concentration. Kinetic analysis and in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed significantly reduced acetone accumulation on PtCu compared to pure Pt, indicating enhanced resistance to catalyst poisoning. Density functional theory (DFT) calculations further identified the first proton-coupled electron transfer (PCET) as the rate-determining step (RDS) with C-H bond scission as the preferred pathway on PtCu. A proof-of-concept PtCu-catalyzed H-cell demonstrated stable cycling over 200 cycles, validating the feasibility of IPA as a low-cost, regenerable redox couple. These findings highlight PtCu-catalyzed IPA/acetone(ACE) chemistry as a promising platform for next-generation aqueous-organic RFBs.

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