Photo‐Induced Construction and Recovery of Cu + Sites in Metal–Organic Frameworks

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 19; no. 40; p. e2302885
• Main Authors: Li, Yu‐Xia, Li, Ke‐Di, Qian, Xin‐Yu, Liu, Xiao‐Qin, Sun, Lin‐Bing
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.10.2023
• Subjects: Chemical bonds; Complexation; Copper; Light irradiation; Metal-organic frameworks; Nanotechnology; Oxidation; Reagents; Recovery; Reducing agents; Valence; cuprous species; CO adsorption; photoreduction; valence adjustment; recovery
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202302885

The adjustment of the valence state of metal ions is crucial for various applications because peculiar activity originates from metal ions with specific valence. Cu + can interact with molecules possessing unsaturated bonds like CO via π ‐complexation, while Cu 2+ doesn't have such ability. Meanwhile, Cu + sites are easily oxidized to Cu 2+ , leading to the loss of activity. Despite great efforts, the development of a facile method to construct and recover Cu + sites remains a pronounced challenge. Here, for the first time a facile photo‐induced strategy is reported to fabricate Cu + sites in metal–organic frameworks (MOFs) and recover Cu + after oxidation. The Cu 2+ precursor was loaded on NH 2 ‐MIL‐125, a typical visible‐light responsive Ti‐based MOF. Visible light irradiation triggers the formation of Ti 3+ from Ti 4+ in framework, which reduces the supported Cu 2+ in the absence of any additional reducing agent, thus simplifying the process for Cu + generation significantly. Due to π ‐complexation interaction, the presence of Cu + results in remarkably enhanced CO capture capacity (1.16 mmol g −1 ) compared to NH 2 ‐MIL‐125 (0.49 mmol g −1 ). More importantly, Cu + can be recovered conveniently via re‐irradiation when it is oxidized to Cu 2+ , and the oxidation‐recovery process is reversible.