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Metal single‐atom (SA) catalysts have attracted immense attention due to the high catalytic efficiency given by the desired coordination environment of each metal atom. Yet, engineering the local electronic structure of SAs and multi‐atoms (MAs) still remains a challenge. Herein, an atomically dispersed catalyst comprised of Pt SAs, Pt‐Pt/V dual‐atoms, and small clusters supported on a vanadium and nitrogen co‐doped carbon (VNC) (denoted as Pt@VNC) surface is synthesized. In the Pt@VNC, both V and Pt atoms are evenly distributed on the surface of N‐doped carbon, while a few Pt atoms are linked to other Pt atoms via V, forming Pt clusters. The coordination structures of Pt atoms are modulated upon introducing atomically dispersed V sites (which generate small‐sized Pt clusters) and V2O5 clusters, showing extraordinary activity for the hydrogen evolution reaction (HER). Benefiting from the low charge transfer resistance, i.e., fast reaction kinetics, due to the synergistic effect of SAs and clusters, the Pt@VNC demonstrates superior catalytic efficiency and robust durability for the HER. It requires an overpotential of only 5 mV at a current density of 10 mA cm−2 and shows 15 times larger mass activity than the commercial 20 wt.% Pt/C catalyst. This novel catalyst‐design strategy paves a new way for maximizing catalytic efficiency by optimizing the coordination structure of metal atoms. [ABSTRACT FROM AUTHOR]

Designing a facile strategy to access active and atomically dispersed metallic catalysts are highly challenging for single atom catalysts (SACs). Herein, a simple and fast approach is demonstrated to construct Pt catalysts with single atoms in large quantity via ball milling Pt precursor and N‐doped carbon support (K2PtCl4@NC‐M; M denotes ball‐milling). The as‐prepared K2PtCl4@NC‐M only requires a low overpotential of 11 mV and exhibits 17‐fold enhanced mass activity for the electrochemical hydrogen evolution compared to commercial 20 wt% Pt/C. The superior hydrogen evolution reaction (HER) catalytic activity of K2PtCl4@NC‐M can be attributed to the generation of Pt single atoms, which improves the utilization efficiency of Pt atoms and the introduction of Pt‐N2C2 active sites with near‐zero hydrogen adsorption energy. This viable ball milling method is found to be universally applicable to the fabrication of other single metal atoms, for example, rhodium and ruthenium (such as Mt‐N2C2, where Mt denotes single metal atom). This strategy also provides a promising and practical avenue toward large‐scale energy storage and conversion application. [ABSTRACT FROM AUTHOR]

Reducing the particle sizes of transition metals [TMs] and avoiding their aggregation are crucial for increasing the TMs atom utilization and enhancing their industrial potential. However, it is still challenging to achieve uniform distributed and density-controlled TMs nanoclusters [NCs] under high temperatures due to the strong interatomic metallic bonds and high surface energy ofNCs. Herein, a series ofTMs NCs with controllable density and nitrogen-modulated surface are prepared with the assistance of a selected covalent organic polymer [COP], which can provide continuous anchoring sites and size-limited skeletons. The prepared Ir NCs show superior hydrogen evolution reaction [HER] and oxygen evolution reaction [OER] activities than commercial Pt/C and Ir/C in both acid and alkaline media. In particular, the as-prepared Ir NCs exhibit remarkable full water splitting performance, reaching a current density of 10 mA cm-2 at ultralow overpotentials of 1.42 and 1.43 V in alkaline and acidic electrolyte, respectively. The excellent electrocatalytic activities are attributed to the increased surface atom utilization and the improved intrinsic activity ofIr NCs. More importantly, the Ir NCs catalyst shows superior long-term stability due to the strong interaction between Ir NCs and the N-doped carbon layer. [ABSTRACT FROM AUTHOR]

Hydrogen generation by electrolysis of water in an alkaline solution is a promising technology for clean hydrogen energy. Amorphous materials show much better performance than their crystalline counterparts. However, it is still challenging to design amorphous metal materials. Here, a series of amorphous transition metal nanoparticles (NPs) is successfully synthesized using a twisted covalent organic network (CON) that can provide twisted carbon layers as well as asymmetrically distributed nitrogen. With the fixed monomer pore, a low loading amount of RuCl3 results in amorphous‐only Ru nanoclusters (NCs, 1.5 nm), while a high content of RuCl3 leads to crystalline dominant Ru NPs (3 nm). The mixed phased Ru‐CON catalyst for the hydrogen evolution reaction (HER) shows extremely low overpotential at 10 mA cm–2 (12.8 mV in 1.0 m KOH) and superior stability (after 100 h test, current loss 5.3% at 75 mA cm–2). More importantly, amorphous‐only Ru‐CON with smaller Ru NCs shows much better mass activity and considerable stability compared to mixed‐phase Ru‐CON materials since amorphous Ru NPs can provide more active sites than in their crystalline state. With this strategy, amorphous Fe NPs and Ir NPs are successfully prepared for extended applications, and the HER activities are reported. [ABSTRACT FROM AUTHOR]

Amorphization of Metal Nanoparticles by 2D Twisted Polymer for Super Hydrogen Evolution Reaction (Adv. Keywords: 2D organic networks; amorphization; amorphous nanomaterials; electrocatalysts; hydrogen evolution reaction EN 2D organic networks amorphization amorphous nanomaterials electrocatalysts hydrogen evolution reaction 1 1 1 04/29/22 20220427 NES 220427 B Hydrogen Evolution Reaction b In article number 2102257 Hyoyoung Lee and co-workers report a novel strategy to synthesize amorphous metal nanoparticles with the help of a twisted covalent organic network. 2D organic networks, amorphization, amorphous nanomaterials, electrocatalysts, hydrogen evolution reaction. [Extracted from the article]