Supplementary information files for Atomically dispersed Fe-N₄ modified with precisely located S for highly efficient oxygen reduction

Supplementary files for article Atomically dispersed Fe-N₄ modified with precisely located S for highly efficient oxygen reduction. Immobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N₃)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N₄ moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N₄ moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-N_x moiety.

本文件为论文《精准定位硫修饰原子级分散Fe-N₄用于高效氧还原反应》的补充材料。通过多氮原子锚定金属原子，因具备高度不饱和配位与强金属-载体相互作用的优势，在诸多关键电化学反应中展现出优异的催化活性。在此，我们合成了一种对Fe配位外围实现精准硫修饰的原子级分散铁氮碳（Fe-NC）材料（命名为Fe-NSC）。X射线吸收近边结构（X-ray absorption near edge structure）分析证实，中心Fe原子以Fe(N₃)(N–C–S)的特定构型得以稳定。通过精准引入局域硫掺杂，可调控Fe-N₄结构单元的电子结构，进而优化Fe活性位点上反应物与中间体的吸附/脱附性能。密度泛函理论（Density functional theory）模拟结果表明，硫掺杂后Fe-N₄结构单元的电荷密度会更负，使得其对*OH中间体的结合能力减弱，同时加速Fe活性位点向氧物种的电荷转移过程。电化学测试结果显示，相较于无硫修饰的Fe-NC材料（命名为Fe-NC），所制备的Fe-NSC样品的氧还原反应性能得到显著提升：在0.1 M KOH电解液中，其起始电位可达1.09 V，半波电位为0.92 V，性能优异。本研究可为通过精准调控M-Nₓ结构单元的局域环境，提升原子级分散M-NC材料催化性能的相关研究提供新思路。

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背景与挑战

背景概述

该数据集是研究“原子分散Fe-N4材料通过精确硫修饰实现高效氧还原”的补充信息文件，发布于2021年3月29日，包含合成、结构分析和电化学性能数据。数据集展示了Fe-NSC材料通过硫掺杂调节电子结构，提升氧还原反应性能，如起始电位达1.09 V，属于化学工程领域，涉及原子分散和硫掺杂等关键词。