Nitrogen fixation is the second most important chemical process in nature next to photosynthesis. Herein, we report a novel g-C3N4/ZnSnCdS heterojunction photocatalyst prepared using the hydrothermal method that has an outstanding nitrogen photofixation ability under visible light. The as-prepared ZnSnCdS is the ternary metal sulfide Zn0.11Sn0.12Cd0.88S1.12 with many sulfur vacancies, not a mixture of ZnS, SnS2, and CdS. Strong electronic coupling, as evidenced by the ultraviolet–visible, X-ray photoelectron spectroscopy, photoluminescence, and electrochemical impedance spectra results, exists between two components in the g-C3N4/ZnSnCdS heterojunction photocatalysts, leading to more effective separation of photogenerated electron–hole pairs and faster interfacial charge transfer. The sulfur vacancies on ternary metal sulfide not only serve as active sites to adsorb and activate N2 molecules but also promote interfacial charge transfer from ZnSnCdS to N2 molecules, thus significantly improving the nitrogen photofixation ability. With the ZnSnCdS mass percentage of 80%, the as-prepared heterojunction photocatalyst exhibits the highest NH4 + generation rate under visible light, which is 33.2-fold and 1.6-fold greater than those of individual g-C3N4 and ZnSnCdS.

Nitrogen fixation is the second most important chemical process in nature, next to photosynthesis. Herein, we report a novel g-C3N4/ZnMoCdS heterojunction photocatalyst with outstanding nitrogen photofixation ability under visible light prepared by hydrothermal post-treatment. The as-prepared ZnMoCdS is the ternary metal sulfide Zn(0.12)Mo(0.12)Cd(0.9)S(1.14) with many sulfur vacancies, not a mixture of ZnS, MoS2 and CdS. Strong electronic coupling, as evidenced by the UV-Vis, XPS and EIS results, exists between two components in g-C3N4/ZnMoCdS heterojunction photocatalysts, leading to more effective separation of photogenerated electron-hole pairs and faster interfacial charge transfer. The sulfur vacancies on ternary metal sulfides not only serve as active sites to adsorb and activate N2 molecules but also promote interfacial charge transfer from the catalyst to N2 molecules, thus significantly improving their nitrogen photofixation ability. With an optimal ZnMoCdS mass percentage of 80%, the as-prepared heterojunction photocatalyst exhibits the highest NH4(+) generation rate under visible light, which is 13.5-fold and 1.75-fold greater than those of individual g-C3N4 and ZnMoCdS, respectively.

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We have demonstrated the plasmonic characteristics of an ultrathin tetrahedral amorphous carbon (ta-C) film coated with Ag nanoparticles. The simulation result shows that, under resonant and non-resonant excitations, the strongest plasmonic electric field of 1 nm ta-C coated Ag nanoparticle is not trapped within the ta-C layer but is released to its outside surface, while leaving the weaker electric field inside ta-C layer. Moreover, this outside plasmonic field shows higher intensity than that of uncoated Ag nanoparticle, which is closely dependent on the excitation wavelength and size of Ag particles. These observations are supported by the SERS measurements. We expect that the ability for ultrathin ta-C coated Ag nanoparticles as the SERS substrates to detect low concentrations of target biomolecules opens the door to the applications where it can be used as a detection tool for integrated, on-chip devices.

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