Search

Constructing atom‐clusters (ACs) with in situ modulation of coordination environment and simultaneously hollowing carbon support are critical yet challenging for improving electrocatalytic efficiency of atomically dispersed catalysts (ADCs). Herein, a general diffusion‐controlled strategy based on spatial confining and Kirkendall effect is proposed to construct metallic ACs in N,P,S triply‐doped hollow carbon matrix (MACs/NPS−HC, M=Mn, Fe, Co, Ni, Cu). Thereinto, FeACs/NPS−HC with the best catalytic activity for oxygen reduction reaction (ORR) is thoroughly investigated. Unlike the benchmark sample of symmetrical N‐surrounded iron single‐atoms in N‐doped carbon (FeSAs/N−C), FeACs/NPS−HC comprises bi‐/tri‐atomic Fe centers with engineered S/N coordination. Theoretical calculation reveals that proper Fe gathering and coordination modulation could mildly delocalize the electron distribution and optimize the free energy pathways of ORR. In addition, the triple doping and hollow structure of carbon matrix could further regulate the local environment and allow sufficient exposure of active sites, resulting in more enhanced ORR kinetics on FeACs/NPS−HC. The zinc‐air battery assembled with FeACs/NPS−HC as cathodic catalyst exhibits all‐round superiority to Pt/C and most Fe‐based ADCs. This work provides an exemplary method for establishing atomic‐cluster catalysts with engineered S‐dominated coordination and hollowed carbon matrix, which paves a new avenue for the fabrication and optimization of advanced ADCs. [ABSTRACT FROM AUTHOR]

The catalytic activity of main‐group metal is hard to promote because of the intrinsic lack of host d orbitals available to be combined. Herein, under the guidance of theoretical predictions, we find atom‐dispersed antimony sites (Sb−N4 moieties) can be activated to achieve high oxygen reduction reaction (ORR) activity using a functional group regulation strategy. Correspondingly, we manage to synthesize a main‐group Sb single‐atom catalysts (SACs) that comprises Sb−N4 active moieties functionalized by epoxy groups in the second microenvironment and incorporated in N‐doped graphene (Sb1/NG(O)). The electron‐rich epoxy group can adjust the electronic structure of Sb−N4 active moieties, thereby optimizing the adsorption of the intermediate. The Sb SACs are comparable to industrial Pt/C under alkaline conditions. This discovery provides new opportunities to manipulate and improve the catalytic activity of main‐group‐element electrocatalysts. [ABSTRACT FROM AUTHOR]

Use of catalytic materials is regarded as the most desirable strategy to cope with sluggish kinetics of lithium polysulfides (LiPSs) transformation and severe shuttle effect in lithium–sulfur batteries (LSBs). Single‐atom catalysts (SACs) with 100 % atom‐utilization are advantagous in serving as anchoring and electrocatalytic centers for LiPSs. Herein, a novel kind of tungsten (W) SAC immobilized on nitrogen‐doped graphene (W/NG) with a unique W‐O2N2‐C coordination configuration and a high W loading of 8.6 wt % is proposed by a self‐template and self‐reduction strategy. The local coordination environment of W atom endows the W/NG with elevated LiPSs adsorption ability and catalytic activity. LSBs equipped with W/NG modified separator manifest greatly improved electrochemical performances with high cycling stability over 1000 cycles and ultrahigh rate capability. It indicates high areal capacity of 6.24 mAh cm−2 with robust cycling life at a high sulfur mass loading of 8.3 mg cm−2. [ABSTRACT FROM AUTHOR]

Highlights: [•] We prepared controlledly the silver nanoparticles on TiO2/SiO2 film by the facile photoreduction under the aid of structure-directing agents. [•] We studied the effect of silver loading on the antibactierial behavior of TiO2 film and optimized the content of silver. [•] We extended the route to fabricate other metals on substrates. [ABSTRACT FROM AUTHOR]