RongQin Ye,HuaBin Fang,Yan-Zhen Zheng,Nan Li,Yuan Wang,Xia Tao
A novel direct Z-scheme CoTiO3/g-C3N4 (CT-U) photocatalytic system with different weight percentage of CoTiO3 was synthesized using a facile in situ growth method for H2 evolution from water splitting. The as-prepared CT-U composites composed of 1D CoTiO3 microrod and 2D g-C3N4 nanosheet were characterized by various techniques including XRD, SEM, TEM, XPS, FTIR, and UV–vis. Results demonstrate that the CT-U composite photocatalysts were successfully fabricated, with intimate interfacial contact and heterojunction interaction between g-C3N4 and CoTiO3 which can significantly boost the photocatalytic activity compared with prinstine g-C3N4 and CoTiO3. The most enhanced H2-evolution rate of 858 μmol h–1 g–1 and high quantum efficiency (38.4% at 365 nm, 3.23% at 420 ± 20 nm) are achieved at an optimal 0.15% CT-U. Meanwhile, the 0.15% CT-U sample exhibits good photocatalytic stability in recycling H2 evolution. Accordingly, direct Z-scheme mechanism capable of leading efficient charge carrier separation and strong reduction ability for enhanced H2 production was proposed, and further evidenced by PL, photoelectrochemical analysis, and ESR assay.
Photocatalysts featuring S-scheme heterojunctions offer considerable potential for both the photocatalytic CO 2 conversion and the degradation of antibiotics, providing practical solutions for energy crises and environmental challenges. In this work, 1D/2D CoTiO 3 /g-C 3 N 4 (CTO/CN) S-scheme heterojunction is synthesized through electrospinning and calcination . The close interweaving of g-C 3 N 4 nanosheets around CoTiO 3 nanofibers creates ample contact areas and active sites, resulting in exceptional photocatalytic CO production capability. The optimal mass ratio of CoTiO 3 to g-C 3 N 4 is 2%, and the CO and CH 4 yields are 46.5 and 0.825 μmol g -1 h -1 . Moreover, comparing with monomeric g-C 3 N 4 , this composite achieves a better CO yield with 43.5 times and displays an impressive product selectivity of 98.3% for CO 2 -CO photoreduction . In addition, the 2% CTO/CN photocatalyst demonstrates outstanding photocatalytic degradation efficiency, with degradation rates of 95.88%, 95.53%, and 71.23% for tetracycline hydrochloride , oxytetracycline , and ofloxacin , respectively. These enhanced photocatalytic properties are attributed to the S-scheme system constructed by CoTiO 3 with g-C 3 N 4 , maintaining strong oxidation-reduction capabilities while efficiently segregating photogenerated charges, with the existence of S-scheme heterojunction confirmed through various analyses. Furthermore, in situ studies and 13 C calibration experiments reveal that CO and CH 4 originate from the photocatalytic CO 2 conversion, further highlighting the potential of this work in advancing CO 2 photoreduction . This study offers novel insights into designing effective S-scheme heterojunction photocatalysts for practical applications to address environmental and energy challenges.
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