Single-atom catalysts based on metal–N4 moieties and anchored on carbon supports (defined as M–N–C) are promising for oxygen reduction reaction (ORR). Among those, M–N–C catalysts with 4d and 5d ...transition metal (TM4d,5d) centers are much more durable and not susceptible to the undesirable Fenton reaction, especially compared with 3d transition metal based ones. However, the ORR activity of these TM4d,5d–N–C catalysts is still far from satisfactory; thus far, there are few discussions about how to accurately tune the ligand fields of single-atom TM4d,5d sites in order to improve their catalytic properties. Herein, we leverage single-atom Ru–N–C as a model system and report an S-anion coordination strategy to modulate the catalyst’s structure and ORR performance. The S anions are identified to bond with N atoms in the second coordination shell of Ru centers, which allows us to manipulate the electronic configuration of central Ru sites. The S-anion-coordinated Ru–N–C catalyst delivers not only promising ORR activity but also outstanding long-term durability, superior to those of commercial Pt/C and most of the near-term single-atom catalysts. DFT calculations reveal that the high ORR activity is attributed to the lower adsorption energy of ORR intermediates at Ru sites. Metal–air batteries using this catalyst in the cathode side also exhibit fast kinetics and excellent stability.
Pursuing active and durable water splitting electrocatalysts is of vital significance for solving the sluggish kinetics of the oxygen evolution reaction (OER) process in energy supply. Herein, ...theoretical calculations identify that the local distortion-strain effect in amorphous RuTe
system abnormally sensitizes the Te-pπ coupling capability and enhances the electron-transfer of Ru-sites, in which the excellent inter-orbital p-d transfers determine strong electronic activities for boosting OER performance. Thus, a robust electrocatalyst based on amorphous RuTe
porous nanorods (PNRs) is successfully fabricated. In the acidic water splitting, a-RuTe
PNRs exhibit a superior performance, which only require a cell voltage of 1.52 V to reach a current density of 10 mA cm
. Detailed investigations show that the high density of defects combine with oxygen atoms to form RuO
H
species, which are conducive to the OER. This work offers valuable insights for constructing robust electrocatalysts based on theoretical calculations guided by rational design and amorphous materials.
Structurally ordered intermetallic phases have exhibited higher and higher electrocatalytic activity and stability than disordered alloys in many reactions such as the oxygen reduction reaction (ORR) ...and small-molecule (hydrogen, formic acid, or ethanol) oxidation reactions. The enhanced electrocatalytic activity could be derived from the definite composition and predictable control over structural, geometric, and electronic effects. This review, based on the understanding of the catalytic mechanism of structurally ordered intermetallic nanoparticles, provides a comprehensive acknowledgment of how the particle size and morphology affect the catalytic performance. The strategy for reducing particle size and the impact of particle size on electrocatalysis will be first introduced. Then, recent developments in the synthesis and design of morphology-controlled catalysts are summarized. The structure–activity relationship between the catalytic activity and morphology including core–shell/hollow and porosity will be highlighted. Finally, the current challenges and future developments are provided. On the basis of this review, intermetallic nanoparticles will shed light on the future development of electrocatalysts for fuel cells and metal-air batteries.
Rechargeable battery technologies have ignited major breakthroughs in contemporary society, including but not limited to revolutions in transportation, electronics, and grid energy storage. The ...remarkable development of rechargeable batteries is largely attributed to in-depth efforts to improve battery electrode and electrolyte materials. There are, however, still intimidating challenges of lower cost, longer cycle and calendar life, higher energy density, and better safety for large scale energy storage and vehicular applications. Further progress with rechargeable batteries may require new chemistries (lithium ion batteries and beyond) and better understanding of materials electrochemistry in the various battery technologies. In the past decade, advancement of battery materials has been complemented by new analytical techniques that are capable of probing battery chemistries at various length and time scales. Synchrotron X-ray techniques stand out as one of the most effective methods that allow for nearly nondestructive probing of materials characteristics such as electronic and geometric structures with various depth sensitivities through spectroscopy, scattering, and imaging capabilities. This article begins with the discussion of various rechargeable batteries and associated important scientific questions in the field, followed by a review of synchrotron X-ray based analytical tools (scattering, spectroscopy, and imaging) and their successful applications (ex situ, in situ, and in operando) in gaining fundamental insights into these scientific questions. Furthermore, electron microscopy and spectroscopy complement the detection length scales of synchrotron X-ray tools and are also discussed toward the end. We highlight the importance of studying battery materials by combining analytical techniques with complementary length sensitivities, such as the combination of X-ray absorption spectroscopy and electron spectroscopy with spatial resolution, because a sole technique may lead to biased and inaccurate conclusions. We then discuss the current progress of experimental design for synchrotron experiments and methods to mitigate beam effects. Finally, a perspective is provided to elaborate how synchrotron techniques can impact the development of next-generation battery chemistries.
NH3 synthesis by the electrocatalytic N2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the currently employed industrial method—the Haber–Bosch process—that ...requires high temperature and pressure. We report single Mo atoms anchored to nitrogen‐doped porous carbon as a cost‐effective catalyst for the NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks, this catalyst achieves a high NH3 yield rate (34.0±3.6 μgNH3
h−1 mgcat.−1) and a high Faradaic efficiency (14.6±1.6 %) in 0.1 m KOH at room temperature. These values are considerably higher compared to previously reported non‐precious‐metal electrocatalysts. Moreover, this catalyst displays no obvious current drop during a 50 000 s NRR, and high activity and durability are achieved in 0.1 m HCl. The findings provide a promising lead for the design of efficient and robust single‐atom non‐precious‐metal catalysts for the electrocatalytic NRR.
Single molybdenum atoms anchored on nitrogen‐doped porous carbon were designed and synthesized for the electrocatalytic reduction of N2 to NH3. The catalyst exhibited high electrocatalytic activity and stability, which is attributed to its structure, conductive carbon support, high porosity, and well‐dispersed single molybdenum atoms.
Aqueous zinc ion batteries are receiving unprecedented attention owing to their markedly high safety and sustainability, yet their lifespan particularly at high rates is largely limited by the poor ...reversibility of zinc metal anodes, due to the random ion diffusion and sluggish ion replenishment at the reaction interface. Here, a tunnel‐rich and corona‐poled ferroelectric polymer‐inorganic‐composite thin film coating for Zn metal anodes to tackle above problems, is proposed. It is demonstrated that the poled ferroelectric coating can better deconcentrate and self‐accelerate ion migration at coating/Zn interface during the electroplating process than untreated ferroelectric coating and bare Zn, thus enabling a compact and horizontally‐aligned Zn morphology even at ultrahigh rates. Notably, a maximal cumulative plating capacity of over 6500 mAh cm−2 (at 10 mA cm−2) is achieved for the surface‐modified Zn metal anode, showing extraordinary reversibility of Zn plating/stripping. This work provides new insights in stabilizing Zn metal electrodeposition at the scale of interfacial ion diffusion.
The random ion diffusion and sluggish cation replenishment at the reaction interface are blamed for the poor high‐rate stability of zinc metal anodes. In this work, a tunnel‐rich and corona‐poled ferroelectric polymer‐inorganic‐composite coating is proposed, which endows self‐accelerated and homogenized cation migration during Zn plating. Consequently, horizontally‐aligned Zn morphology with high reversibility is achieved under ultra‐high cycling current densities.
Lithium (Li) metal, a typical alkaline metal, has been hailed as the “holy grail” anode material for next generation batteries owing to its high theoretical capacity and low redox reaction potential. ...However, the uncontrolled Li plating/stripping issue of Li metal anodes, associated with polymorphous Li formation, “dead Li” accumulation, poor Coulombic efficiency, inferior cyclic stability, and hazardous safety risks (such as explosion), remains as one major roadblock for their practical applications. In principle, polymorphous Li deposits on Li metal anodes includes smooth Li (film-like Li) and a group of irregularly patterned Li (e.g., whisker-like Li (Li whiskers), moss-like Li (Li mosses), tree-like Li (Li dendrites), and their combinations). The nucleation and growth of these Li polymorphs are dominantly dependent on multiphysical fields, involving the ionic concentration field, electric field, stress field, and temperature field, etc. This review provides a clear picture and in-depth discussion on the classification and initiation/growth mechanisms of polymorphous Li from the new perspective of multiphysical fields, particularly for irregular Li patterns. Specifically, we discuss the impact of multiphysical fields’ distribution and intensity on Li plating behavior as well as their connection with the electrochemical and metallurgical properties of Li metal and some other factors (e.g., electrolyte composition, solid electrolyte interphase (SEI) layer, and initial nuclei states). Accordingly, the studies on the progress for delaying/suppressing/redirecting irregular Li evolution to enhance the stability and safety performance of Li metal batteries are reviewed, which are also categorized based on the multiphysical fields. Finally, an overview of the existing challenges and the future development directions of metal anodes are summarized and prospected.
Advances in self-assembly over the past decade have demonstrated that nano- and microscale particles can be organized into a large diversity of ordered three-dimensional (3D) lattices. However, the ...ability to generate different desired lattice types from the same set of particles remains challenging. Here, we show that nanoparticles can be assembled into crystalline and open 3D frameworks by connecting them through designed DNA-based polyhedral frames. The geometrical shapes of the frames, combined with the DNA-assisted binding properties of their vertices, facilitate the well-defined topological connections between particles in accordance with frame geometry. With this strategy, different crystallographic lattices using the same particles can be assembled by introduction of the corresponding DNA polyhedral frames. This approach should facilitate the rational assembly of nanoscale lattices through the design of the unit cell.
Abstract
Electrochemical synthesis of H
2
O
2
through a selective two-electron (2e
−
) oxygen reduction reaction (ORR) is an attractive alternative to the industrial anthraquinone oxidation method, ...as it allows decentralized H
2
O
2
production. Herein, we report that the synergistic interaction between partially oxidized palladium (Pd
δ+
) and oxygen-functionalized carbon can promote 2e
−
ORR in acidic electrolytes. An electrocatalyst synthesized by solution deposition of amorphous Pd
δ+
clusters (Pd
3
δ+
and Pd
4
δ+
) onto mildly oxidized carbon nanotubes (Pd
δ+
-OCNT) shows nearly 100% selectivity toward H
2
O
2
and a positive shift of ORR onset potential by ~320 mV compared with the OCNT substrate. A high mass activity (1.946 A mg
−1
at 0.45 V) of Pd
δ+
-OCNT is achieved. Extended X-ray absorption fine structure characterization and density functional theory calculations suggest that the interaction between Pd clusters and the nearby oxygen-containing functional groups is key for the high selectivity and activity for 2e
−
ORR.
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