Abstract
The ideal solid oxide fuel cells (SOFCs) can be powered by readily available hydrocarbon fuels containing impurities. While this is commonly recognized as a key advantage of SOFC, it also, together with the elevated operating temperature, becomes the main barrier impeding the in-situ or operando investigations of the anode surface chemistry. Here, using a well-designed quenching experiment, we managed to characterize the near-surface structure of La0.4Sr0.6TiO3+δ (LST) anode in SOFCs fuelled by H2S-containing methane. This new method enabled us to clearly observe the surface amorphization and sulfidation of LST under simulated SOFC operating conditions. The ∼1 nm-thick two dimensional sulfur-adsorbed layer was on top of the disordered LST, containing –S, –SH and elemental sulfur species. In SOFC test, such “poisoned” anode showed increased performances: a ten-fold enhanced power density enhancement (up to 30 mW cm−2) and an improved open circuit voltage (from 0.69 V to 1.17 V). Moreover, its anodic polarization resistance in methane decreased to 21.53 Ω cm2, a difference of 95% compared with the sulfur-free anode. Control experiments confirmed that once the adsorbed sulfur species were removed electrochemically, methane conversion slowed down simultaneously till full stop.
Highlights
Fuel diversity is, supposedly, one of the most advantageous features of solid oxide fuel cells (SOFCs) [1e3]
Using a well-designed quenching experiment, we managed to characterize the near-surface structure of La0.4Sr0.6TiO3þd (LST) anode in SOFCs fuelled by H2S-containing methane
Scanning transmission electron microscopy (STEM) analyses were carried out using a FEI's Tecnai Osiris microscope equipped with high angle annular dark field (HAADF) STEM detector
Summary
One of the most advantageous features of solid oxide fuel cells (SOFCs) [1e3]. While most of the current approaches are unable to fully suppress the sulfur poisoning effect, the extensive studies revealed an interesting phenomenon: as a notorious catalyst poison, H2S, in many cases, can be a catalyst as well (namely, promoter), leading to the catalytic performance increase [24e27] These seemingly contradictory results reflect the lack of understanding of the interaction between the anode catalyst and H2S under SOFC operating environment. In this work, using a well-tailored quenching test, we managed to characterize the surface structure evolution of La0.4Sr0.6TiO3þd (LST) anode in SOFCs fuelled by H2S-containing methane This facile method helps us explore the sulfur promoting effects of methane conversion in intermediate-temperature SOFCs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
