B dopant evolution in Pd catalysts after H evolution/oxidation reaction in alkaline environment

TL;DR

This study investigates how boron dopants in palladium catalysts degrade after hydrogen evolution/oxidation reactions in alkaline environments, revealing that hydrogen absorption destabilizes boron within the catalyst structure.

Contribution

It provides new insights into the stability of interstitial dopants in Pd catalysts under electrochemical conditions, combining experimental observations with ab-initio calculations.

Findings

Significant boron removal after H evolution/oxidation

Hydrogen absorption destabilizes sub-surface boron

Catalyst activity drops due to microstructural degradation

Abstract

Introduction of interstitial dopants has opened a new pathway to optimize nanoparticle catalytic activity for, e.g., hydrogen evolution/oxidation and other reactions. Here, we discuss the stability of a property-enhancing dopant, B, introduced through controlled synthesis of an electrocatalyst Pd aerogel. We observe significant removal of B after the hydrogen evolution/oxidation reaction. Ab-initio calculations show that the high stability of sub-surface B in Pd is substantially reduced when H is ad/absorbed on the surface, favoring its departure from the host nanostructure. The destabilization of sub-surface B is more pronounced as more H occupies surface sites and empty interstitial sites. We hence demonstrate that the H2 fuel/product itself favors the microstructural degradation of the electrocatalyst and an associated drop in activity.