Coupling Single-Ni-Atom with Ni–Co Alloy Nanoparticle for Synergistically Enhanced Oxygen Reduction Reaction

Abstract

Developing nonprecious metal-based oxygen reduction reaction (ORR) electrocatalysts with superior activity and durability is crucial for commercializing proton-exchange membrane (PEM) fuel cells. Herein, we report a metal–organic framework (MOF)-derived unique N-doped hollow carbon structure (NiCo/hNC), comprising of atomically dispersed single-Ni-atom (NiN4) and small NiCo alloy nanoparticles (NPs), for highly efficient and durable ORR catalysis in both alkaline and acidic electrolytes. Density functional theory (DFT) calculations reveal the strong coupling between NiN4 and NiCo NPs, favoring the direct 4e– transfer ORR process by lengthening the adsorbed O–O bond. Moreover, NiCo/hNC as a cathode electrode in PEM fuel cells delivered a stable performance. Our findings not only furnish the fundamental understanding of the structure–activity relationship but also shed light on designing advanced ORR catalysts.

Single-Atomic Co–N4 Sites with CrCo Nanoparticles for Metal–Air Battery-Driven Hydrogen Evolution

“…Based on XAS findings, an atomic model is established for CrCo/CoN 4 @CNT-5 which consists of Co–N 4 and CrCo NP composites sites, stabilized on N-doped CNT support (Figure h). Interestingly, the other possible single-atom configurations such as Cr–N 4 were not observed, which might be because of the use of dilute H 2 during carbonization process, comparatively low carbonization temperature (550 °C), and inert nature of Cr 3+ …”

“…Interestingly, the other possible single-atom configurations such as Cr−N 4 were not observed, which might be because of the use of dilute H 2 during carbonization process, comparatively low carbonization temperature (550 °C), and inert nature of Cr 3+ . 70 Electrocatalytic HER performance of CrCo/CoN 4 @CNT-5 and supporting catalysts were evaluated in both acidic and basic electrolyte using a standard three-electrode setup. CrCo/ CoN 4 @CNT-5 shows high HER activity with small overpotential values of 73.7 and 161.4 mV for achieving a current density of 10 mA cm −2 in 0.…”

Ordered mesoporous carbon with binary CoFe atomic species for highly efficient oxygen reduction electrocatalysis

“…However, an in-depth understanding of the interaction between the active sites and reactants to accelerate the ORR kinetics is still heavily hampered by the heterogeneity of the structure and composition of the electrocatalysts, 6,27 while establishing a definitive correlation between the atomic structure and the ORR catalytic performance remains a challenge. 30,31…”

Atomically Dispersed Metal‐Nitrogen‐Carbon Electrocatalysts for the Oxygen Reduction Reaction

“…Meanwhile, the ORR activity of M-N-C electrocatalysts can be optimized by modifying the center metal and coordination environment. To date, a broad range of center metals (e. g., Fe, [15][16][17][18][19][20][21] Co, [22][23][24][25][26][27][28] Ni, [29][30][31][32][33][34] Cu, [35][36][37][38][39][40][41] Cr, [42][43][44][45] Mn, [46][47][48][49][50][51][52][53][54][55] etc.) have been developed, with particular emphasis on the Fe-N-C structure, which has drawn considerable attention for exhibiting superior ORR activity compared to Pt in alkaline solution.…”