The steric effect caused by the lattice mismatch between the two phases hinders the separation and transfer of photogenerated carriers, which is one of the important factors limiting the activity of heterojunction photocatalysts. In this paper, semi - coherent interface Cu2O/Cu7S4 heterojunction was successfully constructed based on the epitaxy growth method of anion exchange. The degradation of tetracycline by semi - coherent interface Cu 2 O/Cu 7 S 4 -30 heterojunction under simulated visible light reached 95.3 % at 60 min, which is a significant improvement compared with single-phase catalysts and ordinary heterojunction catalysts (Cu 2 O/Cu 7 S 4 -mix). The experimental characterization and theoretical calculations confirmed the existence of unique S-Cu-O chemical bonds in the semi - coherent interface Cu 2 O/Cu 7 S 4 heterojunction. On the basis of heterojunction energy band bending and the formation of built-in electric fields, the S-Cu-O bonds can act as a specific bridge to further facilitate the separation, transfer and delivery of photoelectrons and holes, which contributes to the generation of more oxidatively active species (mainly superoxide radicals and holes). In addition, based on experimental characterization and theoretical calculations, the intermediates, degradation pathways and photodegradation mechanisms of the degradation process have also been discussed in detail.
Long Cheng,Rong Wang,Wenzhe Si,Yanxi Deng,Junhua Li,Yue Peng
Cu-based catalysts leveraging Cu+/Cu0 active sites have emerged as pivotal for synthesizing essential hydrocarbons and alcohols in electrochemical CO2 reduction, such as ethylene and ethanol (C2 products). However, the dynamic reduction of Cu+ to Cu0 during electroreduction leads to site instability, resulting in diminished efficiency for CO2 conversion to C2 products. Herein, we introduced Si into CuO by the selective dissolution method, engendering Cu–O–Si units to stabilize the Cu+/Cu0 sites. The catalyst manifested good activity in CO2 electroreduction with an elevated Faradaic efficiency for C2 products reaching 81.9% at −100 mA/cm2. After ten cycles of electrochemical testing, the Cu+/Cu0 sites and performance exhibited no signs of degradation. The Si incorporation significantly improved the hybridization of O 2p and Cu 3d orbitals, thereby reinforcing the Cu–O bonds and stabilizing the Cu+/Cu0 sites, which was critical in promoting C–C coupling via decreasing the energy barriers for *OCCO formation and enhancing C2 product selection. The active Cu+ cations with unsaturated coordination contributed to the reaction stabilization, thereby improving the preservation of Cu2O metastable state.
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