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Nitrogen photoreduction is a promising ammonia production technology since it can be carried out at the atmospheric pressure by merely utilizing the abundant solar energy. However, the low conversion efficiency is still a big challenge for practical applications. In this work, Bi-decorated g-C 3 N 4 nanosheets are successfully prepared by an in situ solvothermal method. The ultraviolet−visible diffuse reflection spectrum shows that Bi decoration conspicuously enhances the visible light absorption because of the surface plasmon resonance effect of the Bi semimetal. Moreover, the photoluminescence spectrum demonstrates that Bi decoration greatly improves the charge separation efficiency because the high work function of Bi (4.5 eV) favors electron transfer from the conduction band of g-C 3 N 4 to the Bi surface. Meanwhile, nitrogen sorption isotherms show that Bi decoration obviously increases the Brunauer−Emmett−Teller surface area (4.3 m 2 g −1 for g-C 3 N 4 vs 7.7−8.4 m 2 g −1 for Bi/g-C 3 N 4 ), which is beneficial for N 2 adsorption. Additionally, the density functional theory calculation shows that the adsorption energy (E ad ) of N 2 on Bi/g-C 3 N 4 (−2.3 eV) is 6.2 times higher than that on g-C 3 N 4 (−0.3 eV), which indicates that N 2 is easier to adsorb on Bi/g-C 3 N 4 thermodynamically. It is assumed that the decorated Bi can also provide new active sites that significantly improve the adsorption and activation of N 2 . Therefore, Bi/g-C 3 N 4 exhibits a high nitrogen photoreduction activity under visible light irradiation (λ > 420 nm): the ammonia yield over 30-Bi/g-C 3 N 4 (3075 μmol L −1 g −1 ) is 1.8 times higher than that over g-C 3 N 4 (1076 μmol L −1 g −1 ) and the ammonia production rate over 30-Bi/g-C 3 N 4 (1025 μmol L −1 g −1 h −1 ) is 1.8 times higher than that over g-C 3 N 4 (359 μmol L −1 g −1 h −1 ). The improved activity is mainly attributed to the Bi decoration on the g-C 3 N 4 surface, which improves the adsorption and activation of N 2 , the electron−hole separation efficiency, and the light-harvesting ability. This work demonstrates that similar to precious metals, Bi semimetal can also greatly improve the nitrogen photoreduction activity. Most importantly, Bi semimetal is more abundant and cheaper than precious metals, and it could be more promising for practical applications.

Efficient cell capture and release methods are important for single-cell analysis of pathological samples. It requires not only strong cell binding but also mild cell release to maximize the number of collected cells while maintaining their viability. Here, we report a smart cell capture and release system based on self-assembling adhesive peptide nanofibers. We installed a versatile surface binding motif, 3, 4-dihydroxyphenylalanine to the C-terminus of a self-assembling peptide. We show that the designed peptide can self-assemble at physiological pH to establish strong cell and substrate binding. The binding strength is dramatically reduced upon the dissembling of the peptide fibers triggered by raising the pH to slightly basic. We demonstrate the efficient capture of four different cells using this system. The capture rates are comparable to fibrin glue and the released cells retain higher viability than those released by enzymatic digestion approaches. Given that this method is highly efficient, biocompatible, and easy to implement, we anticipate that this approach can be widely applied to cell capture and release for single cell analysis and cell therapy.

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