Abstract
Metal nanoparticles anchored on perovskite through in situ exsolution under reducing atmosphere provide catalytically active metal/oxide interfaces for CO2 electrolysis in solid oxide electrolysis cell. However, there are critical challenges to obtain abundant metal/oxide interfaces due to the sluggish diffusion process of dopant cations inside the bulk perovskite. Herein, we propose a strategy to promote exsolution of RuFe alloy nanoparticles on Sr2Fe1.4Ru0.1Mo0.5O6−δ perovskite by enriching the active Ru underneath the perovskite surface via repeated redox manipulations. In situ scanning transmission electron microscopy demonstrates the dynamic structure evolution of Sr2Fe1.4Ru0.1Mo0.5O6−δ perovskite under reducing and oxidizing atmosphere, as well as the facilitated CO2 adsorption at RuFe@Sr2Fe1.4Ru0.1Mo0.5O6−δ interfaces. Solid oxide electrolysis cell with RuFe@Sr2Fe1.4Ru0.1Mo0.5O6−δ interfaces shows over 74.6% enhancement in current density of CO2 electrolysis compared to that with Sr2Fe1.4Ru0.1Mo0.5O6−δ counterpart as well as impressive stability for 1000 h at 1.2 V and 800 °C.
Highlights
Solid oxide electrolysis cell (SOEC) for CO2 electrolysis can efficiently convert renewable electricity into chemical energy as stored in CO1–4
The atomic-scale dynamic structure evolution of SFRuM perovskite under the reducing and oxidizing atmosphere is investigated using in situ scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectrum (EELS), in combination with in situ X-ray diffraction (XRD) and density functional theory (DFT) calculations
A few small-size metal NPs emerged until the reduction temperature reached 800 °C (Fig. 1a), which were apparently present on the surface after continuous reduction for ~30 min (Fig. 1b)
Summary
Solid oxide electrolysis cell (SOEC) for CO2 electrolysis can efficiently convert renewable electricity into chemical energy as stored in CO1–4. The perovskites undergoing redox exsolution exhibit unique catalytic activity, thermal stability, and coking resistance in SOEC, solid oxide fuel cell (SOFC), and other heterogeneous catalytic reactions[11,12,13,14,15,16]. Several strategies have been developed to promote the exsolution of metal NPs such as A-site defect[18,24,25], phase transformation engineering[26,27], and topotactic ion exchange[28,29], etc. We propose a strategy to promote the exsolution of RuFe alloy NPs on Sr2Fe1.4Ru0.1Mo0.5O6−δ (SFRuM) perovskite by enriching the active Ru underneath the surface via repeated redox manipulations. The repeated redox manipulations result in the enrichment of Ru underneath the SFRuM perovskite surface and facilitate abundant exsolution of RuFe alloy NPs under reducing atmosphere. The in situ grown RuFe@SFRuM interfaces facilitate CO2 adsorption and boost CO2 electrolysis performance in SOEC with impressive stability for 1000 h
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