Photocatalytic performance for N2 fixation of the as-synthesized W18O49 nanowires under different light irradiation. (a) Solar simulator (AM 1.5G, 100 mW/cm2). (b) 730 nm LED (2.95 mW/cm2). (c) Molar percentage of NH4+ and NO3- under the irradiation of different wavelength light. (d) The CQE of the as-synthesized W18O49 nanowires under monochromatic light irradiation along with the light absorption spectra.