# Annealing Effects on Cu Migration in the Colloidal Synthesis of Pd-Chalcogenides Nanoheterostructures

## TL;DR

This paper shows how annealing affects copper migration in nanoheterostructures, leading to efficient hydrogen evolution electrocatalysts.

## Contribution

The study reveals a novel mechanistic link between cation mobility and temperature during nanoheterostructure synthesis.

## Key findings

- Moderate-temperature annealing enables complete Cu+ migration in Pd-Cu3Pd13S6.65Te0.35 nanoheterostructures.
- The resulting structures show efficient and stable electrocatalytic hydrogen evolution in acidic media.
- Computational analysis identifies active sites responsible for the catalytic performance.

## Abstract

Heterostructuring
nanocrystals into a modular metal–semiconductor
configuration enables tunable and novel functionalities. Such combinations
at the nanoscale equip hybrid structures with unique electronic, optical,
and catalytic properties unobserved in single-phase materials. Here,
we report the hot-injection synthesis of Pd-Cu3Pd13S6.65Te0.35 nanoheterostructures (NHCs) from
PdCu nanoalloy seeds. First, the growth of Pd-rich chalcogenide nanocrystals
was initiated over the preformed PdCu surface through simultaneous
sulfidation and tellurization, followed by their transformation into
Pd-Cu3Pd13S6.65Te0.35 NHCs.
By strategically employing moderate-temperature annealing, we achieved
the complete migration of Cu+ due to the higher reactivity
of Cu in comparison to Pd at that temperature, establishing a novel
mechanistic relationship between cation mobility and temperature.
This strategy enables controlled semiconductor domain formation and
targeted metal migration. The NHCs showed efficient and stable electrocatalytic
hydrogen evolution with low Tafel values in acidic media, outperforming
conventional nanoelectrocatalysts. Computational analysis identified
the active sites responsible for the observed catalytic performance.