ABSTRACT
Photocatalytic N2 fixation is a promising strategy for ammonia (NH3) synthesis; however, it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2 adsorption/activation capability. Herein, an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2 fixation photocatalyst. The CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSx hollow dodecahedron. Within the heterojunction, the electronic interaction between ZnS and CoSx creates electron-deficient Zn sites with enhanced N2 chemisorption and electron-sufficient Co sites with active hydrogen supply for N2 hydrogenation, cooperatively reducing the energy barrier for N2 activation. In combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure, an excellent N2 fixation performance with a high NH3 yield of 1175.37 µmol g-1 h-1 is achieved. This study provides new insights into the design of heterojunction photocatalysts for N2 fixation.
ABSTRACT
Photocatalysis is a promising technology to resolve energy and environmental issues, where the design of high-efficiency photocatalysts is the central task. As an emerging family of photocatalysts, semiconducting metal-organic frameworks (MOFs) with remarkable features have demonstrated great potential in various photocatalytic fields. Compared to MOF-based photocatalysts with a single component, construction of S-scheme heterojunctions can render MOFs with enhanced charge separation, redox capacity and solar energy utilization, and thus improved photocatalytic performance. Herein, an overview of the recent advances in the design of MOF-based S-scheme heterojunctions for photocatalytic applications is provided. The basic principle of S-scheme heterojunctions is introduced. Then, three types of MOF-based S-scheme heterojunctions with different compositions are systematically summarized including MOF/non-MOF, MOF-on-MOF and MOF-derived heterojunctions. Afterwards, the enhanced performances of MOF-based S-scheme heterojunctions in hydrogen production, CO2 reduction, C-H functionalization, H2O2 production and wastewater treatment are highlighted. Lastly, the current challenges and future prospects regarding the design and applications of MOF-based S-scheme heterojunctions are discussed to inspire the further development of this emerging field.
ABSTRACT
BACKGROUND: New-onset systemic lupus erythematosus (SLE) during pregnancy and in the postpartum period is rare, especially when complicated with pre-eclampsia, which is difficult to diagnose accurately. Here, we report a patient with new-onset SLE and antiphospholipid syndrome during pregnancy, which presented as pre-eclampsia at admission. CASE SUMMARY: A 28-year-old primigravid woman was admitted to our hospital in the 27th wk of gestation with the primary diagnosis of severe pre-eclampsia. Although spasmolysis and antihypertensive therapy were administered since admission, the 24-h proteinuria of the 2nd day after admission reached 10311.0 mg. In the 47th h of admission, immunologic examinations revealed increased levels of anti-double stranded DNA antibody, anti-nuclear antibody, anti-cardiolipin antibody, anti-Sjögren's syndrome-related antigen A antibody and anti-nucleosome antibody and decreased levels of complement C3 and C4. One hour later, ultrasonography of the lower limbs showed thrombus of the bilateral popliteal veins. The diagnosis of SLE and antiphospholipid syndrome was indicated. In the 54th h, the patient manifested with convulsion, dyspnea and blurred vision. Ten hours later, intrauterine death was revealed by ultrasonography. Emergent surgery consisting of inferior vena cava filter implantation and subsequent cesarean section was performed. Following glucocorticoid and anticoagulation therapy after delivery, the patient had an optimal response with improvements in symptoms and immunological markers. CONCLUSION: Obstetricians should be aware of the symptoms and immunological examination results to distinguish pre-eclampsia and underlying SLE for optimal pregnancy outcomes.
