簡單的自頂向下直接金屬霧化和配位策略在二氧化碳光還原中實現高周轉數
作者:
小柯機器人發布時間:2020/11/2 16:33:13
課題組演示了一個簡單的策略,在一個相對較低的溫度(500°C)來達到原位金屬霧化和通過熱驅動氣體酸的配位調節。使用這種策略,來自NH4Cl的熱解氣液酸(HCl)可以將大金屬顆粒縮小成相應的離子,然後將其固定在富氮碳(NC)基質的表面缺陷上。此外,低溫處理誘導的在NC夾層間的C═O結構可以在垂直方向和離散鐵位點成鍵,最後生成在NC基質淺表面具有高價態 (Fe3+)的穩定Fe-N4O物種。
研究發現,Fe-N4O物種在接受來自同質和異質光催化劑的高能電子時可以實現高效的CO2轉化。經過優化的樣品在CO生成1小時內可實現最大周轉數(TON)為1494,具有86.7%的高選擇性和出色的穩定性。實驗和理論結果揭示,與傳統低化學價態的Fe-N4結構相比,高價鐵位點Fe-N4O物種可以促進二氧化碳的吸附,降低關鍵中間體COOH*的生成能壘。
他們的發現通過考慮優化高性能CO2光還原的原子構型,為構建更高效的單原子助催化劑提供了新的觀點。
據悉,發展獨特的單原子作為活性位點對提高光催化CO2還原效率至關重要,但直接霧化金屬粒子和同時調節單個原子的構成仍然具有挑戰性。
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