Construction of 2D/2D g-C3N4/CeO2 heterojunction and its oxygen vacancy mediated photocatalytic activity
Résumé
In this work, a novel oxygen vacancy mediated 2D/2D g-C3N4/CeO2 S-scheme heterojunction was constructed through a hydrothermal method by combing carboxylated g-C3N4 (C-g-C3N4) with CeO2 sheets treated by hydrogen (CeO2-S-H2). The ratio of Ce 3+ /Ce 4+ in CeO2 was increased from 28.2% to 32.08% through hydrogen treatment, which further improved visible light absorption and charges separation efficiency of heterojunction. As a result, C-g-C3N4/CeO2-S-H2 heterojunction exhibited excellent CO2 reduction activity compared with pure C-g-C3N4 and CeO2. The highest CO yields in 8 h of 60%C-g-C3N4/CeO2-S-H2 was 2.41, 6.83 and 1.72 times that of pure C-g-C3N4, CeO2-S and CeO2-S-H2, respectively. Interestingly, the amount of CH4 generated by C-g-C3N4 was negligible. However, CH4 yields of 60%C-g-C3N4/CeO2-S-H2 reached 11.997 umol/g in 8 h. The results indicated that the introduction of oxygen vacancies can effectively enhance CH4 production, which can be used as a reference for the development of photocatalysts with high activity and selectivity. Simultaneously, the C-g-C3N4/CeO2-S-H2 heterojunction also demonstrated the good ciprofloxacin degradation activity. The possible S-scheme photocatalytic mechanism of C-g-C3N4/CeO2-S-H2 heterojunction was proposed. This study provides a new idea for the design of photocatalysts with high efficiency of converting carbon dioxide into solar fuels.
Domaines
Chimie
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