科學家利用小於3納米的超細氧化亞銅實現可見光固氮
作者：
小柯機器人發布時間：2020/10/28 12:54:37
中科院理化技術研究所的張鐵銳團隊的最新研究製備了小於3納米的超細氧化亞銅（Cu2O），實現了可見光碟機動的固氮作用。 相關論文於近日發表在《德國應用化學》雜誌上。
在該研究中，團隊使用抗壞血酸，通過對一種含二價銅的層狀雙氫氧化物進行原位拓撲還原反應，成功製備了尺寸均一、橫向尺寸小於3納米的超細氧化亞銅小片。襯底支撐的超細氧化亞銅高效、穩定地實現了可見光碟機動的N2→NH3光催化還原反應（在400nm波長的光催化下，按照氧化亞銅的質量歸一化後的反應速率高達4.10 mmol·gCu2O-1·h-1）。如此高的活性可能源自光生電子被陷阱捕獲後具有較長壽命、足夠多的活化位點被暴露以及襯底材料的特性。這項工作指導了用於合成氨或其他應用的超細催化劑的未來設計。
據了解，利用水作為還原劑的光催化固氮反應是一種在未來很有前景的合成氨策略，因此研究人員一直在尋找具有高可見光利用率和固氮效率的光催化劑。氧化亞銅作為一種低成本、可見光響應的半導體光催化劑，代表著一類從熱力學角度上非常理想但被研究甚少的可見光固氮反應催化劑。
值得注意的是，到目前為止大部分氧化亞銅光催化劑由於較大的橫向尺寸（通常約數十到數百納米），普遍存在嚴重的電子-空穴複合和表面積有限等問題，制約了其在固氮光催化反應中的應用。在這樣的背景下，橫向尺寸約為1-3 nm的超細光催化劑與傳統的基於納米粒子的光催化劑相比具有明顯的優勢，但超細光催化劑的可控合成仍是一個具有挑戰性的課題。
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