High-density single-atomic Ni–N4 sites for efficient Fenton-like reactions,Journal of Materials Chemistry A

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High-density single-atomic Ni–N4 sites for efficient Fenton-like reactions
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2024-09-11 , DOI: 10.1039/d4ta05189k
Shu-Qi Wang _{1,

2} , Katherine Velez ₁ , Jiahui Cai ₁ , Linbo Huang ₂ , Qing-Hua Zhang ₃ , Feng Feng ₁ , Qi An ₁ , Lu Zhao ₁ , Jin-Song Hu _{2,

4}

Affiliation

Maximizing the number of exposed active sites or regulating the coordination environment of catalysts is important for advanced oxidation processes to produce highly reactive radicals and destroy organic contaminants. Single-atom catalysts (SACs) have great potential as Fenton-like catalysts owing to a high utilization rate of atoms and their unique features bridging the gap between homogeneous and heterogeneous catalysis. Here, single-atom Ni dispersed on N-doped nanoporous carbon (Ni–NC) with a relatively high Ni loading of 9.3 wt% was prepared by a cascade anchoring strategy. Isolated Ni–N₄ sites are fully exposed in Ni–NC, which display excellent catalytic activity by activating H₂O₂ and generating sufficient OH in Fenton-like catalytic oxidation of organic contaminants. Taking the degradation of methylene blue for an example, the degradation rate constant of Ni–NC is up to 0.767 min⁻¹, higher than that of Ni₃N/C with an Ni–N structure in interstitial sites of Ni₆N₂ octahedra (0.226 min⁻¹) and NiO/C with an Ni–O structure (0.016 min⁻¹). Combined with density functional theory (DFT) calculations, the high-density Ni–N₄ moiety obtained from high single-atom Ni loading enhances charge transfer at the reaction interface and reduces the free energy barrier for H₂O₂ activation, thereby enabling a remarkable rapid degradation of contaminants. Moreover, the degradation reactor designed with Ni–NC realizes approximately 100% MB removal during 6 h continuous operation. This work highlights the effect of structure and loading for metal centers on catalytic oxidation reactions.

中文翻译：

高密度单原子 Ni-N4 位点可实现高效的类芬顿反应

最大化暴露的活性位点数量或调节催化剂的配位环境对于高级氧化过程产生高反应性自由基并破坏有机污染物非常重要。单原子催化剂（SAC）由于原子利用率高且其独特的功能弥合了均相和多相催化之间的差距，因此作为类芬顿催化剂具有巨大的潜力。在这里，通过级联锚定策略制备了分散在氮掺杂纳米多孔碳（Ni-NC）上的单原子镍，其镍负载量相对较高，为 9.3 wt%。 Ni-NC中孤立的Ni-N ₄位点完全暴露，在有机污染物的类芬顿催化氧化中，通过活化H ₂ O ₂并产生足够的OH，表现出优异的催化活性。以降解亚甲基蓝为例，Ni-NC的降解速率常数高达0.767 min ^-1 ，高于Ni ₆ N ₂八面体间隙位点具有Ni-N结构的Ni ₃ N/C。 (0.226 min ^-1 ) 和具有 Ni-O 结构的 NiO/C (0.016 min ^-1 )。结合密度泛函理论（DFT）计算，高单原子Ni负载量获得的高密度Ni-N ₄部分增强了反应界面的电荷转移，降低了H ₂ O ₂活化的自由能垒，从而实现了污染物的显着快速降解。此外，采用 Ni-NC 设计的降解反应器在连续运行 6 小时期间实现了约 100% 的 MB 去除率。这项工作强调了金属中心的结构和负载对催化氧化反应的影响。

更新日期：2024-09-11

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