Atomically Dispersed Isolated Fe–Ce Dual-Metal-Site Catalysts for Proton-Exchange Membrane Fuel Cells

Abstract

Atomically dispersed single-metal-site catalysts are hailed as the most promising category for the oxygen reduction reaction (ORR) with full metal utilization and complete exploitation of intrinsic activity. However, due to the inherent electronic structure of single-metal atoms in MN x , it is difficult to break the linear relationship between catalytic activity and adsorption energy of reaction intermediates, and the performance of such catalysts still falls short of expectations. Herein, we change the adsorption structure by constructing Fe−Ce atomic pairs to modulate the iron d-orbital electron configuration, breaking the linear relationship based on single-metal sites. The 4f cruise electrons of cerium element reduce the dorbital center of iron in the synthesized FeCe-single atom dispersed hierarchical porous nitrogen-doped carbon (FeCe-SAD/HPNC) catalyst, and more orbitaloccupied states appear near the fermi level, which weakens the adsorption strength in the active center and oxygen species, so that the rate-determining step was shifted from *OH desorption to *O > *OH, rendering the excellent ORR performances of the FeCe-SAD/HPNC catalyst. The synthesized FeCe-SAD/HPNC catalyst shows excellent activity, with a half-wave potential as high as 0.81 V for ORR in 0.1 M HClO 4 solution. Additionally, by constructing a three-phase reaction interface with a hierarchical porous structure, the H 2 −O 2 proton-exchange membrane fuel cell (PEMFC) assembled with FeCe-SAD/HPNC as cathode catalyst achieves a maximum power density of 0.771 W cm −2 and good stability.

Promising Ce single-atom-dispersed nitrogen-doped graphene catalysts for the hydrogen evolution reaction

“…Studies have shown that the presence of both defective carbon and graphitized carbon plays a significant role in improving electrochemical performance by fine-tuning the local electronic and geometric characteristics of the carbon matrix. 5 XPS was performed to quantitatively analyze the chemical compositions of the as-prepared materials (C, N, and Ce). Here, C, N, and Ce were detected in Ce/NGr, which is consistent with the elemental mapping results.…”

“…For example, only the outer surface metal atoms are primarily used in nanomaterials, while the inner atoms remain uninvolved. 5 Single-atom catalysts (SACs) have been reported as efficient electrocatalysts for the HER because of their maximum atomic utilization, high activity, selectivity, and stability. 6,7 However, preparing SACs without aggregation is quite challenging because of their high surface energy.…”

“…Thus far, metal N-doped carbon SACs have played the most vital role in electrocatalysis. 5,8,9 Utilizing REE-SACs as potential materials for electrocatalysis can be a crucial research direction since REEs provide distinctive electronic structures due to the spin–orbit coupling of their 4f and valence orbitals. 10,11 Among REEs, Ce stands out because of its rich electronic orbital configuration, which includes unique 4f orbitals that exhibit complex chemical states with variable oxidation states and coordination numbers.…”

Dual and Triple Atom Electrocatalysts for Energy Conversion (CO2RR, NRR, ORR, OER, and HER): Synthesis, Characterization, and Activity Evaluation

“…Electrolyte is either 0.1 M HClO 4 or 0.5 M H 2 SO 4 (shaded gray). References: [A], [B], [C], [D], [E], [F], [G], [H], [I], [J], [K], [L], [M], [N], [O], [P], [Q], [R], [S], [T], [U], [V], [W] …”

Recent Advances in Non‐Precious Metal Single‐Atom Electrocatalysts for Oxygen Reduction Reaction in Low‐Temperature Polymer‐Electrolyte Fuel Cells

“…Inspiringly, Zhou et al reported ZIF-8derived FeÀ Ni-based DAC that delivered P max of 865 mW cm À 2 under H 2 /O 2 at 2.0 bar, although AST was not done. [145] Researchers have also chosen other and more rare combinations with Fe to develop DACs, for instance, FeÀ Cu-NÀ C, [139] FeÀ Ce-SAD/HPNC, [142] and Fe/Zr-NC. [147] Amongst these, Fe/Zr-NÀ C DAC by Chi et al [147] delivered outstanding PEMFC performance with P max of 1200 and 720 mW cm À 2 under H 2 /O 2 and H 2 /air conditions, respectively.…”