Surface plasmon-enhanced photo-driven CO2 hydrogenation by hydroxy-terminated nickel nitride nanosheets.

The majority of visible light-active plasmonic catalysts are often limited to Au, Ag, Cu, Al, etc., which have considerations in terms of costs, accessibility, and instability. Here, we show hydroxy-terminated nickel nitride (Ni3N) nanosheets as an alternative to these metals. The Ni3N nanosheets catalyze CO2 hydrogenation with a high CO production rate (1212 mmol g-1 h-1) and selectivity (99%) using visible light. Reaction rate shows super-linear power law dependence on the light intensity, while quantum efficiencies increase with an increase in light intensity and reaction temperature. The transient absorption experiments reveal that the hydroxyl groups increase the number of hot electrons available for photocatalysis. The in situ diffuse reflectance infrared Fourier transform spectroscopy shows that the CO2 hydrogenation proceeds via the direct dissociation pathway. The excellent photocatalytic performance of these Ni3N nanosheets (without co-catalysts or sacrificial agents) is suggestive of the use of metal nitrides instead of conventional plasmonic metal nanoparticles.