日本物质材料研究所Jinhua Ye研究组取得一项新突破。他们研制了灵巧的自上而下的策略直接金属雾化和配位调节实现高周转率二氧化碳光还原。相关论文于2020年10月29日发表于《美国化学会志》。

课题组演示了一个简单的策略，在一个相对较低的温度(500°C)来达到原位金属雾化和通过热驱动气体酸的配位调节。使用这种策略，来自NH₄Cl的热解气液酸（HCl）可以将大金属颗粒缩小成相应的离子，然后将其固定在富氮碳（NC）基质的表面缺陷上。此外，低温处理诱导的在NC夹层间的C═O结构可以在垂直方向和离散铁位点成键，最后生成在NC基质浅表面具有高价态 (Fe³⁺)的稳定Fe-N₄O物种。

研究发现，Fe-N₄O物种在接受来自同质和异质光催化剂的高能电子时可以实现高效的CO₂转化。经过优化的样品在CO生成1小时内可实现最大周转数（TON）为1494，具有86.7％的高选择性和出色的稳定性。实验和理论结果揭示，与传统低化学价态的Fe-N₄结构相比，高价铁位点Fe-N₄O物种可以促进二氧化碳的吸附，降低关键中间体COOH*的生成能垒。

他们的发现通过考虑优化高性能CO₂光还原的原子构型，为构建更高效的单原子助催化剂提供了新的观点。

据悉，发展独特的单原子作为活性位点对提高光催化CO₂还原效率至关重要，但直接雾化金属粒子和同时调节单个原子的构成仍然具有挑战性。

附：英文原文

Title: Facile Top-Down Strategy for Direct Metal Atomization and Coordination Achieving a High Turnover Number in CO₂ Photoreduction

Author: Yunxiang Li, Shengyao Wang, Xu-sheng Wang, Yu He, Qi Wang, Yingbo Li, Mengli Li, Gaoliang Yang, Jundong Yi, Huiwen Lin, Dekang Huang, Lan Li, Hao Chen, Jinhua Ye

Issue&Volume: October 29, 2020

Abstract: Developing unique single atoms as active sites is vitally important to boosting the efficiency of photocatalytic CO₂ reduction, but directly atomizing metal particles and simultaneously adjusting the configuration of individual atoms remain challenging. Herein, we demonstrate a facile strategy at a relatively low temperature (500 °C) to access the in situ metal atomization and coordination adjustment via the thermo-driven gaseous acid. Using this strategy, the pyrolytic gaseous acid (HCl) from NH₄Cl could downsize the large metal particles into corresponding ions, which subsequently anchored onto the surface defects of a nitrogen-rich carbon (NC) matrix. Additionally, the low-temperature treatment-induced C═O motifs within the interlayer of NC could bond with the discrete Fe sites in a perpendicular direction and finally create stabilized Fe–N₄O species with high valence status (Fe³⁺) on the shallow surface of the NC matrix. It was found that the Fe–N₄O species can achieve a highly efficient CO2 conversion when accepting energetic electrons from both homogeneous and heterogeneous photocatalysts. The optimized sample achieves a maximum turnover number (TON) of 1494 within 1 h in CO generation with a high selectivity of 86.7% as well as excellent stability. Experimental and theoretical results unravel that high valence Fe sites in Fe–N₄O species can promote the adsorption of CO₂ and lower the formation barrier of key intermediate COOH* compared with the traditional Fe–N₄ moiety with lower chemical valence. Our discovery provides new points of view in the construction of more efficient single-atom cocatalysts by considering the optimization of the atomic configuration for high-performance CO₂ photoreduction.

DOI: 10.1021/jacs.0c09060

Source: https://pubs.acs.org/doi/10.1021/jacs.0c09060