Recent advances in high‐loading catalysts for low‐temperature fuel cells: From nanoparticle to single atom

Atomically dispersed and nitrogen coordinated single metal site (MNx, M = Fe, Co, or Mn) moieties embedded in partially graphitized carbon (denoted as M–N–C) are recognized as the most promising platinum group metal‐free catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. However, simply regulating their coordination environments and local structures of single metal sites cannot fundamentally change active site structure, which leads to insufficient activity and stability. A second transition metal can be incorporated to design dual‐metal sites, offering a new opportunity to modulate the electronic and geometric structures of M–N–C catalysts. Therefore, exploring optimal atomically dispersed dual‐metal‐site is essential to designing new active sites with enhanced ORR activity, and stability, especially breaking the activity‐stability trade‐off. This review provides a comprehensive analysis of the advances in developing atomically dispersed dual‐metal site catalysts for the ORR, including innovative synthesis methods, primary structural configurations, and the mechanisms to promote catalytic performance. We aim to elucidate the crucial structure–property correlation, emphasizing the inherent electronic and geometric effects of dual metal sites. Finally, we discuss the current challenges of dual‐metal site catalysts concerning rational design, precise synthesis, and high‐fidelity structural characterization.

Section: Introductionmentioning

confidence: 99%

Atomically dispersed dual‐metal‐site PGM‐free electrocatalysts for oxygen reduction reaction: Opportunities and challenges

Yang

Priest

Hou

et al. 2022

“…The highly increased energy demand of modern society has attracted enormous attention for developing renewable and clean energy sources, among which solar energy is considered as a promising candidate. [1][2][3][4][5][6][7] Photo-driven water splitting has been regarded as a sustainable and cost-efficient strategy to generate clean hydrogen (H 2 ) fuel to realize a stable supply of renewable energy. 5,8,9 Semiconductor materials have received great research attention due to their unique chemical, physical, and optoelectronics characteristics.…”

Section: Introductionmentioning

confidence: 99%

Surface decorated Ni sites for superior photocatalytic hydrogen production

Huang

Zuo

et al. 2022

Precise construction of isolated reactive centers on semiconductors with wellcontrolled configurations affords a great opportunity to investigate the reaction mechanisms in the photocatalytic process and realize the targeted conversion of solar energy to steer the charge kinetics for hydrogen evolution. In the current research, we decorated isolated Ni atoms on the surface of CdS nanowires for efficient photocatalytic hydrogen production. X-ray absorption fine structure investigations clearly demonstrate the atomical dispersion of Ni sites on the surface of CdS nanowires. Experimental investigations reveal that the isolated Ni atoms not only perform well as the real reactive centers but also greatly accelerate the electron transfer via direct Ni-S coordination. Theoretical simulation further documents that the hydrogen adsorption process has also been enhanced over the semi-coordinated Ni centers through electronic coupling at the atomic scale.

“…Therefore, reducing the noble metal load while maintaining high activity and stability is essential for the design of high‐performance catalysts. The first obvious choice is size reduction to nanoclusters or single atoms to greatly increase the atom utilization efficiency 6–9 . After many years of development, this route has gradually become mature while it still faces challenges such as a clear size‐reduction limit (single atoms) and lack of sufficient tunability (and/or stability) with few atoms.…”

Section: Introductionmentioning

confidence: 99%

High‐entropy alloy stabilized and activated Pt clusters for highly efficient electrocatalysis

Shi

et al. 2022

Although Pt and other noble metals are the state‐of‐the‐art catalysts for various energy conversion applications, their low reserve, high cost, and instability limit their large‐scale utilization. Herein, we report a hybrid catalysts design featuring noble metal clusters (e.g., Pt) uniformly dispersed and stabilized on high‐entropy alloy nanoparticles (HEA, e.g., FeCoNiCu), denoted as HEA@Pt, which is prepared via ultra‐fast shock synthesis (∼300 ms) for HEA alloying combined with Pt galvanic replacement for surface anchoring. In our design, the HEA core critically ensures high dispersity, stability, and tunability of the surface Pt clusters through high entropy stabilization and core‐shell interactions. As an example in the hydrogen evolution reaction, HEA@Pt achieved a significant mass activity of 235 A/gPt, which is 9.4, 3.6, and 1.9‐times higher compared to that of homogeneous FeCoNiCuPt (HEA‐Pt), Pt, and commercial Pt/C, respectively. We also demonstrated noble Ir stabilized on FeCoNiCrMn nanoparticles (HEA‐5@Ir), achieving excellent anodic oxygen evolution performance and highly efficient overall water splitting when combined with the cathodic HEA@Pt. Therefore, our work developed a general catalysts design strategies by using high entropy nanoparticles for effective dispersion, stabilization, and modulation of surface active sites, achieving a harmonious combination of high activity, stability, and low cost.