In this paper, the unclear Ni atom coordination structure evolution in one-pot pyrolysis method synthesizing Ni single atom catalyst using graphitic carbon nitride as support (Ni-g-C₃N₄) was deeply discussed. In-situ X-ray absorption fine structure spectra and other assisted methods were used to characterize the structural evolution. The results demonstrate that the pyrolysis process can be divided into three stages. In the first stage from room temperature to 183 °C (Stage I), the NiCl₂⋅6H₂O was mixed with the supporting material (dicyandiamide) to form the precursor with Ni-(H₂O)₆ octahedral coordination configuration. In the second stage from 183 to 350 °C (Stage II), the H₂O molecules have been removed and the supporting material was converted to melamine. The melamine molecules were polycondensed to melem during 308–350 °C. The intermediates labeled Ni-melamine and Ni-melem was formed with Ni-N₄ planar quadrilateral coordination configuration. In the third stage from 350 to 600 °C (Stage III), the supporting material (melem) was gradually converted to g-C₃N₄, and the Ni-N₄ coordination configurations were replaced by Ni-N₆ planar hexagon coordination configuration one by one. The three Ni coordination configurations were further confirmed by Reverse Monte Carlo simulations and ab initio calculations.

本文对以石墨氮化碳为载体的一锅热解法合成Ni单原子催化剂(Ni-gC 3 N 4 ₎中_不清楚的Ni原子配位结构演化进行了深入探讨。采用原位X射线吸收精细结构谱和其他辅助方法来表征结构演化。结果表明，热解过程可分为三个阶段。在从室温到183°C的第一阶段（阶段I），NiCl ₂ ⋅6H ₂ O与支撑材料（双氰胺）混合，形成具有Ni-(H ₂ O) ₆八面体配位构型的前驱体。在第二阶段 183 至 350 °C（阶段 II）中，H₂ O分子已被去除，支撑材料转化为三聚氰胺。三聚氰胺分子在 308–350 °C 期间缩聚成蜜勒胺。标记为Ni-三聚氰胺和Ni-melem的中间体具有Ni-N ₄平面四边形配位构型。第三阶段350～600℃（Stage III），支撑材料（melem）逐渐转化为gC ₃ N ₄，Ni-N ₄配位构型被Ni-N ₆平面六边形配位构型一取代。一个。通过反向蒙特卡罗模拟和从头计算进一步证实了这三种镍配位构型。