Surface Modification of Electrospun Perovskite Nanofiber Materials via Exsolution Process for Enhance Hydrogen Evolution (X-Seed Project)

A. Tanase¹*, S. Martínez-Crespiera¹, M. Garcia-Montolio¹, David Sieiro Deumal¹, P. Bosch-Jimenez¹

¹Leitat Technological Center Terrassa, Spain

*Presenting author: atanase@leitat.org

Exsolution has become an increasingly utilized process with the ability to tailor the functional properties of materials by modifying the surface chemistry of perovskite oxides and generating catalytically active species from the host lattice. As part of the X-Seed project, three novel perovskite-based nanomaterials (PBCCF, SFM & LBCN) were developed as catalysts for a membrane-less electrolyzer operating under supercritical water conditions (above 374°C and 220 bar). In this work, the exsolution behaviour of PBCCF and its effect on electrochemical performance were investigated.

The PBCCF nanofibers were synthesised using the electrospinning technique from a polymeric solution where the materials were electrospun under optimised flow rates and voltages. A high temperature thermal treatment followed to remove the polymer and crystallise the perovskite phase. Additional thermal treatments at 450 and 650 °C were investigated to promote the migration and exsolution of Co from the perovskite structure towards the surface. The materials were characterised using XRD, ICP-MS, BET and HR-SEM to analyse the structural, compositional and morphological features before and after the exsolution.

The additional thermal treatment promoted the formation of Co-rich metallic species at the nanofiber surface, indicating successful exsolution and redistribution of Co from the internal lattice of the perovskite host. This surface modification was accompanied by a notable enhancement in hydrogen evolution reaction (HER) performance. Compared with the untreated PBCCF material, the exsolved samples exhibited markedly lower HER overpotentials across the investigated current-density range, with the overpotential decreasing from 493 mV to 329 mV at 10 mA cm⁻², corresponding to an improvement of 164 mV (~33%).

These findings highlight controlled exsolution as a promising strategy for tailoring perovskite-based nanofiber catalysts and improving their electrochemical performance.

Acnowledgements

Project X-SEED with Grant Agreement number 101137701. The project is supported by the Clean Hydrogen Partnership and its members. Co-funded by the European Union. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the Clean Hydrogen Partnership. Neither the European Union nor the granting authority can be held responsible for them.

Reference: X-SEED Project - Supercritical Hydrogen