Chemical Partitioning at Crystalline Defects in PtAu as a Pathway to Stabilize Electrocatalysts

TL;DR

This paper demonstrates that engineering solute segregation at crystalline defects in PtAu electrocatalysts significantly enhances their stability and longevity, offering a new pathway for developing durable energy conversion catalysts.

Contribution

It introduces segregation engineering at defects as a novel method to stabilize electrocatalysts, validated through experimental stabilization of Pt with Au addition.

Findings

Au segregation at defects passivates vulnerable sites against dissolution

Stability of PtAu electrocatalysts improved by over an order of magnitude

Defect engineering can be broadly applied to enhance catalyst durability

Abstract

Dissolution of electrocatalysts during long-term and dynamic operation is a challenging problem in energy conversion and storage devices such as fuel cells and electrolyzers. To develop stable electrocatalysts, we adopt the design concept of segregation engineering, which uses solute segregation prone to electrochemical dissolution at internal defects, i.e., grain boundaries and dislocations. We showcase the feasibility of this approach by stabilizing a model Pt catalyst with an addition of more noble Au (approximately 5 atomic percent). We characterized the defects' nanoscale structure and chemistry, and monitored the electrochemical dissolution of Pt and PtAu alloys by online inductively coupled plasma mass spectrometry. Once segregated to defects, Au atoms can stabilize and hence passivate the most vulnerable sites against electrochemical dissolution and improve the stability and longevity of the Pt electrocatalysts by more than an order of magnitude. This opens pathways to use solute segregation to defects for the development of more stable nanoscale electrocatalysts, a concept applicable for a wide range of catalytic systems.