Diode characteristics, piezo-photocatalytic antibiotic degradation and hydrogen production of Ce3+ doped ZnO nanostructures.

Piezo-photocatalysis of ZnO nanostructures had recently well attracted due to their exceptional potential in degrading the antibiotics and scalable hydrogen production. Here, we have synthesized the Ce3+ doped ZnO nanospheres in a facile wet chemical strategy. Dopant ions induced morphological evolution and optical bandgap tuning had observed in our experiment. Optical absorbance spectrum had confirmed the bandgap shortening occurs with Ce3+ doped ZnO specimens. The bandgap gap value had reduced to 2.82 eV from 3.05eV confirming the visible light responsivity of ZnO nano specimens. Obtained Zn(1-x)CexO nanospheres were utilized to fabricate the p-Si/n- Zn(1-x)CexO heterojunction diodes as well studied the improved electrical conductivity for the Ce3+ specimen-based diodes. Besides, ideality factor and barrier height values of the heterojunction diodes ZnO/p-Si, Zn0.99Ce0.01O/p-Si, Zn0.97Ce0.03O/p-Si, and Zn0.95Ce0.05O/p-Si are 15.97 & 0.43 eV, 15.47 & 0.44 eV, 8.02 & 0.46 eV and 5.21 & 0.47 eV, respectively. Direct sunlight assisted piezo-photocatalytic tetracycline (TC) degradation efficiency of ZnO, Zn0.99Ce0.01O, Zn0.97Ce0.03O, and Zn0.95Ce0.05O nanostructures respectively are 64%, 69%, 74% and 82%. We have produced the hydrogen quantity of 1234 µ mol h-1, 1490 µ mol h-1, 1750 µ mol h-1 and 1980 µ mol h-1 with 0%, 1%, 3% and 5% Ce3+ doped ZnO specimens under the direct sunlight assisted piezo-photocatalytic H2 production from H2S splitting.

Comparison of students' perceptions of online and hybrid learning modalities during the covid-19 pandemic: The case of the University of Sharjah.

Hybrid learning enables educators to incorporate elements of conventional face-to-face learning methods with structured online schemes. This study aimed to assess university students' perceptions of online and hybrid learning during the ongoing COVID-19 pandemic. A web-based cross-sectional study was conducted at the University of Sharjah, in the United Arab Emirates (n = 2056). Students' sociodemographic characteristics, perceptions of online and hybrid learning, concerns, and university life changes, were investigated. Perception statements were dichotomized into "positive" and "negative" based on a 50% cut-off point. Scores of > 7 and >5 indicated positive perceptions of online and hybrid learning respectively while scores of ≤ 7 and ≤ 5 indicated negative perceptions. Binary logistic regression analysis was performed to predict students' perceptions of online and hybrid learning according to demographic variables. Spearman's rank-order correlation was performed to determine the relationship between students' perceptions and behaviors. Most students preferred online learning (38.2%) and on-campus learning (36.7%) to hybrid learning (25.1%). Around two-thirds of the students had a positive perception of online and hybrid learning in terms of university support, however, half of them preferred the assessment during online or on-campus learning. Main difficulties reported in hybrid learning were lack of motivation (60.6%), discomfort when on-campus (67.2%), and distraction due to mixed methods (52.3%). Older students (p = 0.046), men (p<0.001), and married students (p = 0.001) were more likely to have a positive perception of online learning, while sophomore students were more likely to have a positive perception of hybrid learning (p = 0.001). In this study, most students preferred online or on-campus over hybrid learning and expressed certain difficulties while on hybrid learning. Future research should focus on investigating the knowledge and capability of graduates from a hybrid/online model compared to a traditional model. Obstacles and concerns should be considered for future planning to ensure the resilience of the educational system.