Unraveling the Mechanism of Water-Mediated Sulfur Tolerance via Operando Surface-Enhanced Raman Spectroscopy

Abstract

While several proton-conducting anode materials have shown excellent tolerance to sulfur poisoning, the mechanism is still unclear due largely to the inability to probe miniscule amounts of sulfur-containing species using conventional surface characterization techniques. Here we present our findings in unraveling the mechanism of water-mediated sulfur tolerance of a proton conductor under operating conditions empowered by surface-sensitive, operando surface-enhanced Raman spectroscopy (SERS) coupled with impedance spectroscopy. Contrary to the conventional view that surface-adsorbed sulfur is removed mainly by oxygen anions, it is found that −SO4 groups on the surface of the proton conductor are converted to SO2 by a water-mediated process, as confirmed by operando SERS analysis and density functional theory (DFT)-based calculations. The combination of operando SERS performed on a model electrode and theoretical computation offers an effective approach to investigate into complex mechanisms of electrode processes in various electrochemical systems, providing information vital to achieve the rational design of better electrode materials.

Water as a hole-predatory instrument to create metal nanoparticles on triple-conducting oxides

“…[19][20][21][22][23][24][25] PCFCs, which employ a proton-conducting ceramic electrolyte, represent one of the most efficient and cleanest devices to generate electric power from a zero-emission fuel (H 2 ). [26][27][28][29][30][31][32] Specifically, the conductive nature of protons, which show significantly lower activation energy (0.4-0.6 eV) compared to oxygen ions, makes PCFCs more attractive in the low to intermediate temperature range (450-650 1C). [33][34][35][36][37][38] In such devices, triple-conducting oxides are capable of being used as an extraordinary O 2 -electrode, as the oxygen reduction reaction (i.e.,…”

Self-assembled nano-composite perovskites as highly efficient and robust hybrid cathodes for solid oxide fuel cells

“…19 However, the strong band feature of BaZr 0.8 Y 0.2 O 3− δ (BZY) perovskite oxides at v = ∼720 cm −1 is not observed in the BSCFZY composite, indicating that the Zr-rich phase is not BZY. 37,38 Rather, when compared to the XRD profiles of BSCF and BCFZY (Fig. S2†), the sample with a smaller lattice more closely approximates the composition of BSCF, while the other sample is closer to that of BCFZY.…”

Isolation of Metalloid Boron Atoms in Intermetallic Carbide Boosts the Catalytic Selectivity for Electrocatalytic N2 Fixation

“…As shown in Figure S13 (Supporting Information), with the increased applied potential from −0.4 to −1.0 V versus RHE, a Raman peak appeared at 981 cm −1 , assigned to the sulfate radical species absorbed on the surface of VC/CNFs, suggesting the excellent wettability for the electrolyte. [ 36 ] For the B 11 ‐VC/CNFs as electrocatalysts (Figure 6e), under applied potential from −0.4 to −0.5 V versus RHE, a new Raman peak emerged at 1525 cm −1 , ascribed to the  NH, demonstrating the strong nitrogen reduction on B 11 ‐VC/CNFs. Time‐resolved in situ Raman spectra of B 11 ‐VC/CNFs collected at −0.6 V versus RHE under a N 2 atmosphere for 1 h were shown in Figure 6f.…”

“…As shown in Figure S13 (Supporting Information), with the increased applied potential from −0.4 to −1.0 V versus RHE, a Raman peak appeared at 981 cm −1 , assigned to the sulfate radical species absorbed on the surface of VC/CNFs, suggesting the excellent wettability for the electrolyte. [36] For the B 11 -VC/CNFs as electrocatalysts (Figure 6e), under applied potential from −0.4 to −0.…”