Accelerating Electrocatalytic Hydrogen Evolution with Ferroelectric Bismuth Ferrite Nanostructures

The high overpotential and Tafel slope of an electrocatalyst significantly limits its effectiveness in energy conversion. To mitigate this issue, optimizing defects and dopants is crucial for developing efficient and environmentally friendly catalysts. Interestingly, ferroelectricity in catalysts like bismuth ferrite (BFO) has a profound impact on their catalytic properties, particularly for water treatment applications.¹ We utilize the electrocatalytic functionality of ferroelectric-doped bismuth ferrite (BiFe_0.95X_0.05O₃; where X = Mn, Co) nanoparticles (NPs) for the hydrogen evolution reaction (HER). The electrocatalytic activity of the pristine nanoparticles undergoes a revolutionary enhancement with the substitution of mono-, di-, and tri-valent cations. Our strategic doping at the Bi and Fe sites results in a significant reduction in the kinetic overpotential required for HER.<br/>We observed that these engineered catalysts exhibit higher HER activity in alkaline media compared to acidic conditions.² This reduction in overpotential in doped NPs is attributed to multiple factors: enhanced local ferroelectricity, decreased charge transfer resistance, increased specific surface area, a wide distribution of pore sizes, particles with abundant active facets, and the introduction of dopants as new active sites on the surface. Additionally, the presence of optimized surface defects, oxygen vacancies, and increased microstrain in these NPs further contributes to the reduction in overpotential and Tafel slopes. We demonstrate that modifying the active sites at the Bi site drastically improves electrocatalytic performance, underscoring the promising future of ferroelectric-catalysts in energy conversion applications.<br/>(1) Dubey, A.; Keat, C. H.; Shvartsman, V. V; Yusenko, K. V; Castillo, M. E.; Buzanich, A. G.; Hagemann, U.; Kovalenko, S. A.; Stähler, J.; Lupascu, D. C. Mono-, Di-, and Tri-Valent Cation Doped BiFe0.95Mn0.05O3 Nanoparticles: Ferroelectric Photocatalysts. <i>Adv. Funct. Mater.</i> <b>2022</b>, <i>2207105</i>, 1–16. https://doi.org/10.1002/adfm.202207105.<br/>(2) Dubey, A.; Sanjuán, I.; Andronescu, C.; Lupascu, D. C. Bi Site Doped Ferroelectric BiFe0.95Mn0.05O3 Nanoparticles for Hydrogen Evolution Reaction. <i>ChemCatChem</i> <b>2024</b>, <i>e202400130</i>, 1–24. https://doi.org/10.1002/cctc.202400130.