Publications by Jan Vávra | EPFL Graph Search

Solution-based Cu+ transient species mediate the reconstruction of copper electrocatalysts for CO2 reduction

Raffaella Buonsanti, Anna Loiudice, Jan Vávra, Petru Pasquale Albertini, Gaétan Philippe Louis Ramona

Understanding metal surface reconstruction is of the utmost importance in electrocatalysis, as this phenomenon directly affects the nature of available active sites. However, its dynamic nature renders surface reconstruction notoriously difficult to study. ...

Nature Portfolio2024

Considerations of Liquid-Phase Transmission Electron Microscopy Applied to Heterogeneous Electrocatalysis

Vasiliki Tileli, Tzu-Hsien Shen, Robin Pierre Alain Girod, Jan Vávra

Liquid-phase transmission electron microscopy (LPTEM) is an essential tool for studying the dynamics of materials interactions at the nanoscale, in and/or with their operational environment. Microfabricated SiNx membrane cells further allow the integration ...

ELECTROCHEMICAL SOC INC2023

Copper-Phosphonate Lamella Intermediates Control the Shape of Colloidal Copper Nanocrystals

Raffaella Buonsanti, Valeria Mantella, Jan Vávra, James Richard Pankhurst, Dragos-Constantin Stoian, Petru Pasquale Albertini

Understanding the structure and behavior of intermediates in chemical reactions is key to developing greater control over the reaction outcome. This principle is particularly important in the synthesis of metal nanocrystals (NCs), where the reduction, nucl ...

2022

The native oxide skin of liquid metal Ga nanoparticles prevents their rapid coalescence during electrocatalysis

Raffaella Buonsanti, Anna Loiudice, Jan Vávra, Laia Castilla Amorós, Valery Okatenko, Dragos-Constantin Stoian

Liquid metals (LMs) have been used in electrochemistry since the 19th century, but it is only recently that they have emerged as electrocatalysts with unique properties, such as inherent resistance to coke-poisoning, which derives from the dynamic nature o ...

2022

Monitoring and understanding Cu catalyst dissolution during CO2 electroreduction

Jan Vávra

Electrochemical reduction of carbon dioxide is a promising approach to decrease the amount of anthropogenic CO2 being released into the atmosphere, provided that a surplus of renewable electrical energy is available. Copper based materials are at the cente ...

EPFL2022

Photoluminescence emission induced by localized states in halide-passivated colloidal two-dimensional WS2 nanoflakes

Michele Saba, Raffaella Buonsanti, Anna Loiudice, Jan Vávra

Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD) materials by surface manipulation is essential to enabling their practical and large-scale application. This is especially challenging for colloidal 2D-TMDs ...

Royal Society of Chemistry2021

Synthetic Tunability of Colloidal Covalent Organic Framework/Nanocrystal Hybrids

Chethana Janardhana Gadiyar, Raffaella Buonsanti, Seyedehbehnaz Varandili, Yannick Thomas Guntern, Vikram Vinayak Karve, Jan Vávra, Ona Segura Lecina

The combination of porous reticular frameworks and nanocrystals (NCs) offers a rich playground to design materials with functionalities, which are beneficial for a large variety of applications. Achieving compositional and structural tunability of these hy ...

2021

Real-time Monitoring Reveals Dissolution/Redeposition Mechanism in Copper Nanocatalysts during the Initial Stages of the CO2 Reduction Reaction

Raffaella Buonsanti, Vasiliki Tileli, Tzu-Hsien Shen, Jan Vávra, Dragos-Constantin Stoian

Size, morphology, and surface sites of electrocatalysts have a major impact on their performance. Understanding how, when, and why these parameters change under operating conditions is of importance for designing stable, active, and selective catalysts. He ...

Wiley-VCH Verlag GmbH2021

Elucidating the structure-dependent selectivity of CuZn towards methane and ethanol in CO2 electroreduction using tailored Cu/ZnO precatalysts

Raffaella Buonsanti, Seyedehbehnaz Varandili, Yannick Thomas Guntern, Jan Vávra, James Richard Pankhurst, Kevin Rossi, Dragos-Constantin Stoian

Understanding the catalyst compositional and structural features that control selectivity is of uttermost importance to target desired products in chemical reactions. In this joint experimental-computational work, we leverage tailored Cu/ZnO precatalysts a ...

2021

Colloidal Nanocrystals as Electrocatalysts with Tunable Activity and Selectivity

Raffaella Buonsanti, Seyedehbehnaz Varandili, Pranit Srinivas Iyengar, Jan Vávra, James Richard Pankhurst, Valery Okatenko, Cedric David Koolen, Dragos-Constantin Stoian

Correlating the catalyst activity, selectivity, and stability with its structure and composition is of the utmost importance in advancing the knowledge of heterogeneous electrocatalytic processes for chemical energy conversion. Well-defined colloidal nanoc ...

2021

Ligand-mediated formation of Cu/metal oxide hybrid nanocrystals with tunable number of interfaces

Raffaella Buonsanti, Seyedehbehnaz Varandili, Jan Vávra, James Richard Pankhurst, Dragos-Constantin Stoian

Combining domains of different chemical nature within the same hybrid material through the formation of heterojunctions provides the opportunity to exploit the properties of each individual component within the same nano-object; furthermore, new synergisti ...

2020

Oxygen Evolution Reaction in Ba0.5Sr0.5Co0.8Fe0.2O3-delta Aided by Intrinsic Co/Fe Spinel-Like Surface

Thi Ha My Pham, Vasiliki Tileli, Tzu-Hsien Shen, Jan Vávra

Among the perovskites used to catalyze the oxygen evolution reaction (OER), Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) exhibits excellent activity which is thought to be related to dynamic reconstruction at the flexible perovskite surface due to accommodation of ...

AMER CHEMICAL SOC2020

Stability and Degradation Mechanisms of Copper-Based Catalysts for Electrochemical CO2 Reduction

Raffaella Buonsanti, Jan Vávra

To date, copper is the only monometallic catalyst that can electrochemically reduce CO2 into high value and energy-dense products, such as hydrocarbons and alcohols. In recent years, great efforts have been directed towards understanding how its nanoscale ...

Wiley-VCH Verlag GmbH2020

Synthesis of Cu/CeO2-x Nanocrystalline Heterodimers with Interfacial Active Sites To Promote CO2 Electroreduction

Mounir Driss Mensi, Emad Oveisi, Chethana Janardhana Gadiyar, Raffaella Buonsanti, Seyedehbehnaz Varandili, Jianfeng Huang, Michal Stanislaw Strach, Gian Luca De Gregorio, Jan Vávra

Synergistic effects at metal/metal oxide interfaces often give rise to highly active and selective catalytic motifs. So far, such interactions have been rarely explored to enhance the selectivity in the electrochemical CO2 reduction reaction (CO2RR). Herei ...

2019

Nanocrystal/Metal–Organic Framework Hybrids as Electrocatalytic Platforms for CO2 Conversion

Mounir Driss Mensi, Raffaella Buonsanti, Pascal Alexander Schouwink, Valeria Mantella, Yannick Thomas Guntern, Jan Vávra, James Richard Pankhurst

The tunable chemistry linked to the organic/inorganic components in colloidal nanocrystals (NCs) and metal–organic frameworks (MOFs) offers a rich playground to advance the fundamental understanding of materials design for various applications. Herein, we ...

Wiley-VCH Verlag GmbH2019