中科院理化技术研究所的张铁锐团队的最新研究制备了小于3纳米的超细氧化亚铜（Cu₂O），实现了可见光驱动的固氮作用。 相关论文于近日发表在《德国应用化学》杂志上。

在该研究中，团队使用抗坏血酸，通过对一种含二价铜的层状双氢氧化物进行原位拓扑还原反应，成功制备了尺寸均一、横向尺寸小于3纳米的超细氧化亚铜小片。衬底支撑的超细氧化亚铜高效、稳定地实现了可见光驱动的N₂→NH₃光催化还原反应（在400nm波长的光催化下，按照氧化亚铜的质量归一化后的反应速率高达4.10 mmol·g_Cu2O^-1·h^-1）。如此高的活性可能源自光生电子被陷阱捕获后具有较长寿命、足够多的活化位点被暴露以及衬底材料的特性。这项工作指导了用于合成氨或其他应用的超细催化剂的未来设计。

据了解，利用水作为还原剂的光催化固氮反应是一种在未来很有前景的合成氨策略，因此研究人员一直在寻找具有高可见光利用率和固氮效率的光催化剂。氧化亚铜作为一种低成本、可见光响应的半导体光催化剂，代表着一类从热力学角度上非常理想但被研究甚少的可见光固氮反应催化剂。

值得注意的是，到目前为止大部分氧化亚铜光催化剂由于较大的横向尺寸（通常约数十到数百纳米），普遍存在严重的电子-空穴复合和表面积有限等问题，制约了其在固氮光催化反应中的应用。在这样的背景下，横向尺寸约为1-3 nm的超细光催化剂与传统的基于纳米粒子的光催化剂相比具有明显的优势，但超细光催化剂的可控合成仍是一个具有挑战性的课题。

附：英文原文

Title: Sub‐3 nm Ultrafine Cu2O for Visible Light‐driven Nitrogen Fixation

Author: Shuai Zhang, Yunxuan Zhao, Run Shi, Chao Zhou, Geoffrey I.N. Waterhouse, Zhuan Wang, Yuxiang Weng, Tierui Zhang

Issue&Volume:

Abstract: Photocatalytic N  2  fixation to NH  3  with water as the reducing agent represents a promising future strategy for ammonia synthesis, motivating the discovery of efficient photocatalysts that offer high sunlight utilization and catalytic efficiency to N  2  fixation. Cu  2  O, a low‐cost, visible light‐responsive semiconductor photocatalyst represents an ideal candidate for visible light‐driven photocatalytic reduction of N  2  to NH  3  from the viewpoint of thermodynamics, but remaining unexplored in this field yet. Noticeably, a majority of Cu  2  O photocatalysts synthesized to date with large lateral sizes (typically tens to hundreds of nanometers) generally suffer from severe electron‐hole recombination and limited surface sites, restricting its photocatalytic activity for potential N  2  fixation. Ultrafine photocatalysts with lateral dimensions ~1‐3 nm offer distinct advantages over conventional nanoparticle‐based photocatalysts in this context, though the controlled synthesis of ultrafine photocatalysts remains challenging. Herein, we report the successful synthesis of uniformly sized and ultrafine Cu  2  O platelets with lateral size < 3 nm  via  the  in‐situ  topotactic reduction of a Cu(II)‐containing layered double hydroxide with ascorbic acid. The supported ultrafine Cu  2  O offered excellent performance and stability for the visible light‐driven photocatalytic reduction of N  2  to NH  3  (the Cu  2  O‐mass‐normalized rate as high as 4.10 mmol gCu  2  O  ‐1  h  ‐1  at λ > 400 nm), with the origin of the high activity being long‐lived photo‐excited electrons in trap states, an abundance of exposed active sites and the underlying support structure. This work guides the future design of ultrafine catalysts for NH  3  synthesis and other applications.

DOI: 10.1002/anie.202013594

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202013594