Figure 1.
XRD patterns of P25, TNT, TiO2, N-TiO2 and Au/N-TiO2.
Asterisk, rhombus, and open star denote rutile, anatase, and Au, respectively.
Figure 2.
(a) TEM image of as synthesized Au/N-TiO2, inset in the lower right corner is the SAED pattern of anatase TiO2 and (b) HRTEM image and (c) EDX spectrum of Au/N-TiO2.
Figure 3.
XPS spectra of (a) Au/N-TiO2 and core level spectra of (b) O 1s, (c) N 1s, and (d) Au 4f.
Figure 4.
UV–vis diffuse reflectance spectra of TiO2, Au/TiO2, N-TiO2, and Au/N-TiO2.
Figure 5.
PL emission spectra of TiO2, Au/TiO2, N-TiO2, and Au/N-TiO2 under the irradiation of 254 nm. nm.
Figure 6.
Photocatalytic activity for water splitting under the irradiation of (a) UV and (b) UV–vis light.
Figure 7.
The repeated hydrogen evolution tests over Au/N-TiO2 under UV-vis light in (a) pure water and (b) methanol/water solution with purging of Ar in every 8 h. h.
Figure 8.
Photocurrents of TiO2, N-TiO2, Au/TiO2, and Au/N-TiO2 electrodes at zero bias voltage irradiated with (a) UV (λ = 254 nm nm) and (b) visible light (λ>400 nm nm) for 20 s. s.
Figure 9.
EIS Nyquist plots for Au/N-TiO2 in dark and under the irradiation of visible light.
Inset is the suggested equivalent circuit and the fitting results for Au/N-TiO2. Rs and Rct are the electrolyte and electron-transfer resistance, respectively. CPE is the constant phase element, which also represents the double layer capacitance. Ws is the Warburg impedance. Y0 is the value of admittance and expresses a reciprocal relationship to the Warburg coefficient, which is able to predict the Warburg impedance and diffusion coefficient.
Figure 10.
Schematic illustration of Au/N-TiO2 for water splitting under the irradiation of (a) UV and (b) visible light.
Pathway I denotes the generation of charge carriers in TiO2. Pathway II represents the reversible electron transfer between charged diamagnetic Nb− and neutral paramagnetic Nb•, and the excitation of electrons into the conduction band. Pathway III shows the acceleration of photo-induced electrons transfer by Au loading. Pathway IV denotes the SPR effect of loaded Au nanoparticles.