Building narrow band gap semiconductors and fast separation of photogenerated electron-hole (e - -h + ) structures are of great significance for photocatalytic process. In this contribution, the CeO 2-x /C 3-y N 4 /Ce(CO 3 )(OH) double S-scheme heterojunctions with atomic vacancies tunable band gap (2.54 eV) have been designed and fabricated as a boost photocatalyst for enrofloxacin (ENR) photodegradation. Compared with the control samples, the experimental results indicate that the typical sample (CeO 2-x /C 3-y N 4 /Ce(CO 3 )(OH)-2) achieves the highest ENR photodegradation efficiency (93.6 %) in 240 min under a pH of 6, and the possible photodegradation pathways are also proposed. The superior performance is ascribed to the CeO 2-x /C 3-y N 4 /Ce(CO 3 )(OH) double S-scheme heterojunctions for selective recombination of photogenerated electrons with weak-reduction ability in conduction band (CB) of CeO 2-x , C 3-y N 4 and the photogenerated holes with weak-oxidation nature in valance band (VB) of C 3-y N 4 , Ce(CO 3 )(OH), which increase the retention rate of photogenerated electrons in CB of Ce(CO 3 )(OH) and photogenerated holes in VB of CeO 2-x to degrade ENR. This is the first systematic study of CeO 2-x /C 3-y N 4 /Ce(CO 3 )(OH) double S-scheme heterojunctions for ENR photodegradation.
The applications of any two-dimensional (2D) semiconductor devices cannot bypass the control of metal-semiconductor interfaces, which can be severely affected by complex Fermi pinning effects and defect states. Here, we report a near-ideal rectifier in the all-2D Schottky junctions composed of the 2D metal 1 T′-MoTe 2 and the semiconducting monolayer MoS 2 . We show that the van der Waals integration of the two 2D materials can efficiently address the severe Fermi pinning effect generated by conventional metals, leading to increased Schottky barrier height. Furthermore, by healing original atom-vacancies and reducing the intrinsic defect doping in MoS 2 , the Schottky barrier width can be effectively enlarged by 59%. The 1 T′-MoTe 2 /healed-MoS 2 rectifier exhibits a near-unity ideality factor of ~1.6, a rectifying ratio of >5 × 10 5 , and high external quantum efficiency exceeding 20%. Finally, we generalize the barrier optimization strategy to other Schottky junctions, defining an alternative solution to enhance the performance of 2D-material-based electronic devices.
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