Synergistic nitrogen reduction and water oxidation process is significant to the photocatalytic fixation of nitrogen. However, the coupling mechanism remains ambiguous and lacks study. Herein, we report enhanced photocatalytic nitrogen fixation on single-atom Fe-modified macro-/mesoporous TiO2-SiO2 (Fe-T-S), with a high ammonia generation rate of 32 μmol g–1 h–1 without any sacrificial agent and cocatalysts. Experimental and theoretic calculation studies confirmed the formation of a photoinduced hole-trapping polaron on the Fe dopant, resulting in the high-valent Fe­(IV) species. The single-atom Fe­(IV) site is responsible for water oxidation and helps promote N2 hydrogenation on neighboring oxygen vacancy. This study explicitly unravels the key to achieve the coupling between photocatalytic N2 hydrogenation and water oxidation through a doping strategy and provides significant guidance for the rational design of photocatalysts for ammonia synthesis.

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Photocatalytic fixation of nitrogen is a promising method for green conversion of solar light, but has been substantially limited by inefficient activation of the nonpolar N≡N bond and the poor utilization of visible light. In this study, carbon nitride nanosheet composites with abundant nitrogen vacancies and strong plasmonic resonance absorption of visible light have been fabricated through the combination of hydrogen treatment and loading of Au nanoparticles. Ammonia yields of 184 μmol g−1 and 93 μmol g−1 are obtained without any sacrificial agent under full‐light and visible‐light irradiation, respectively. In particular, the visible‐light activity is enhanced tenfold with the help of Au. Combining the experimental results and theoretical calculations, both the hydrogen treatment and Au loading help form nitrogen vacancies on the carbon nitride nanosheets, which promote N2 activation by enhancing the chemisorption. Furthermore, the Au loading further improves the nitrogen reduction efficiency through charging the excited hot electrons formed from the surface plasmonic resonance to the adsorbed N2 molecules.

Incorporation of plasmonic metals into semiconductors are probably the most efficient strategy for improving their photocatalytic hydrogen evolution reaction (HER) activity. This article summarizes recent advances in the development of...