Boosting photocatalytic nitrogen reduction reaction by Jahn-Teller effect.

Compared with traditional the Haber-Bosch process, photocatalytic ammonia production has attracted a considerable attention due to its advantages of low energy consumption and sustainability. In this work, we mainly study the photocatalytic nitrogen reduction reaction (NRR) on MoO·0.55HO and α-MoO. Structure analysis shows that compared to α-MoO, the [MoO] octahedrons in MoO·0.55HO obviously distort (Jahn-Teller distortion), leading to the formation of Lewis acid active sites that favors the adsorption and activation of N. X-ray photoelectron spectroscopy (XPS) further confirms the formation of more Mo as Lewis acid active sites in MoO·0.55HO. Transient photocurrent, photoluminescence and electrochemical impedance spectra (EIS) confirmed that MoO·0.55HO has a higher charge separation and transfer efficiency than α-MoO. Density functional theory (DFT) calculation further confirmed that the N adsorption on MoO·0.55HO is more favorable thermodynamically than that on α-MoO. As a result, under visible light irradiation (λ ≥ 400 nm) for 60 min, an ammonia production rate of 88.6 μmol·g was achieved on MoO·0.55HO, which is about 4.6 times higher than that on α-MoO. In comparison to other photocatalysts, MoO·0.55HO exhibits an excellent photocatalytic NRR activity under visible light irradiation without using sacrificial agent. This work offers a new fundamental understanding to photocatalytic NRR from the viewpoint of crystal fine structure, which benefits designing efficient photocatalysts.