Chunhua Li,Luqian Bao,Yubo Shi,Zhehang Tian,Yixin Ji,Mengyao Cui,Zhilei Zhao,Xianyou Wang
A hollow heterojunction of W-Zr-MOF-NH 2 @TpTt-COF (WZT) was fabricated by combining etched W-Zr-MOF-NH 2 with TpTt-COF. WZT, synthesized through acid etching and hydrothermal methods, showed better tetracycline degradation than pure W-Zr-MOF-NH 2 and pure TpTt-COF due to its larger specific surface area and more active sites. The surface of WZT contains abundant oxygen vacancies (OVs) that capture electrons, promoting the separation of photogenerated e - -h + pairs and increasing WZT’s photocatalytic activity. WZT (1:1, mass) showed 87% degradation of tetracycline under 300 W Xenon lamp irradiation. The results of cycling experiments demonstrated the high stability and reusability of WZT (1:1), making it feasible for production. The excellent photocatalytic degradation of tetracycline by WZT (1:1) originates from the formation of heterojunctions and the presence of surface OVs, which reduces the strong photogenerated e - -h + complexation efficiency. Possible photocatalytic degradation mechanisms are proposed while demonstrating the formation of Z-scheme heterojunction in WZT, which aligned with the experimental results of electron spin resonance (ESR). The tetracycline oxidative decomposition process involves the participation of •OH, 1 O 2 , • O 2 - , e - , and h + as proven by ESR and radical trapping experiments. This work proposes a research idea to prepare high-performance photocatalysts with MOF@COF type, featuring OVs-rich and Z-scheme heterojunctions.
Guanglu Xia,Jianhao Qiu,Dingliang Dai,Lu Zhang,Yong Tang,Jianfeng Yao
A series of covalent organic frameworks (COFs) with β-ketoenamine linkages named TpTt-COF, TAPT-COF, and TpPa-1 were constructed for photocatalytic H 2 O 2 generation in pure water and ambient air under visible light. Among them, TpTt-COF performed striking H 2 O 2 yield of 2647 μmol L −1 , which is 3.5, 17.5, and 176.5-fold those of TAPT-COF, TpPa-1, and bulk g-C 3 N 4 , respectively, attributing to the electron-deficient trait, short charge diffusion distance, and the narrowest bandgap of TpTt-COF. Additionally, to achieve the facile recovery, TpTt-COF was firmly and evenly anchored on melamine sponges (MS) because plenty of amino groups on the surface of MS could be involved in the β-ketoenamine formation and guide the synthesis of TpTt-COF on MS. The corresponding H 2 O 2 evolution over this photocatalyst monolith is also respectable and can be well repeated at least four times. This work is quite instructive for photocatalyst construction based on covalent organic frameworks and facile photocatalytic applications.
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