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N2 fixation is one of the most important chemical reactions in the ecosystem of our planet. However, the industrial Haber-Bosch ammonia synthesis process is restricted by harsh reaction conditions (350-550 °C, 150-350 atm) and undesirable environmental effects (a large amount of CO2 emission). Photocatalytic N2 fixation is promising for achieving sustainable ammonia synthesis under ambient conditions with lower energy input and less environmental issues. However, the known photocatalysts for N2 reduction under mild conditions still face the great challenge of very low energy conversion efficiency. Herein, we report a facile solution-phase method to prepare the heterojunctions based on n-type Bi2MoO6 nanorods and oxygen-vacancy-rich p-type BiOBr nanosheets (Bi2MoO6/OV-BiOBr). Originating from the formation of p-n junctions and suitable bandgap configuration, the Bi2MoO6/OV-BiOBr heterojunctions exhibit effective light utilization and photogenerated electron-hole separation properties. Moreover, it is confirmed that the oxygen vacancies on BiOBr nanosheets are propitious to the adsorption and activation of N2 molecules. Benefiting from these merits, the Bi2MoO6/OV-BiOBr heterojunctions exhibit improved photocatalytic performance for N2 conversion to ammonia without any noble metal co-catalysts and sacrificial reagents under ambient conditions.

Solar-driven photocatalytic overall water splitting is regarded as one of the ideal strategies to generate renewable hydrogen energy without the initiation of environmental issues. However, there are still a few remaining challenges to develop wide-light-absorption and stable photocatalysts for the simultaneous production of H2 and O2 in pure water without sacrificial reagents. Herein, we report the design and preparation of Z-scheme TiO2/ZnTe/Au nanocorncob heterojunctions by homogeneously decorating Au nanoparticles onto the surface of core-shell TiO2/ZnTe coaxial nanorods for highly efficient overall water splitting. With the appropriate band structure of TiO2/ZnTe heterojunctions and the surface plasmon resonance enhancement of Au nanoparticles, the well-designed TiO2/ZnTe/Au nanocorncob heterojunctions can synergistically make effective utilization of broad-range solar light illunimation and enhance the separation efficency of electron-hole pairs, as evidenced by UV-Vis absorption and time-resolved photoluminescence spectroscopy. Photoelectrochemical characterization confirms that the water-splitting reaction on TiO2/ZnTe/Au nanocorncobs is mainly carried out via a two-electron/two-electron transfer process with an intermediate product of H2O2. As a result, the TiO2/ZnTe/Au nanocorncob photocatalyst can generate H2 and O2 with a stoichiometric ratio of 2 : 1 under light irradiation without any sacrificial agents, exhibiting a high H2 production rate of 3344.0 μmol g-1 h-1 and a solar-to-hydrogen (STH) efficiency of 0.98%. Moreover, the TiO2/ZnTe/Au nanocorncob heterojunctions show high stability and well-preserved morphological integrity after long-term photocatalytic tests. This study provides a prototype route to produce clean hydrogen energy from only sunlight, pure water, and rationally-designed heterojunction photocatalysts.