The TEM image (b) shows that the entire NR is coated with QDs from the bottom to the top. Most of the QDs that covered the surface of NR disperse well with an average diameter of 10 nm. A closer observation of the Ag2S QDs attached with TiO2 NR can be obtained by the high resolution transmission electron microscope (HRTEM) https://www.selleckchem.com/products/jq-ez-05-jqez5.html images (Figure 5c,d). The NR grows

along the [001] direction, and lattice fringes with interplanar spacing d 110 = 0.321 nm are clearly imaged. The Ag2S QDs anchoring on the side surface of TiO2 NR are composed of small crystallites as observed by the fringes which correspond to the (121) planes of Ag2S. Figure 5 SEM, TEM, and HRTEM images. SEM image of FTO/TiO2/Ag2S (top view) (a), TEM image of a single TiO2 NR covered with

Ag2S QDs (b), and HRTEM images of TiO2/Ag2S (c,d). Optical and photoelectrochemical properties of see more Ag2S QDs-sensitized TiO2 NRA Figure 6 shows the absorption selleck products spectra of FTO/TiO2 electrode and FTO/TiO2/Ag2S electrodes with different photoreduction times (t p). The absorption edge around 400 nm is consistent with bandgap of rutile TiO2 (3.0 eV). While Ag2S QDs are deposited on TiO2 NRs, absorption spectra are successfully extended to visible wavelength. With t p increasing from 3 to 15 min, the absorption range changes from 400 to 520 nm until covering the entire visible spectrum; moreover, the absorbance obviously increases. The bandgap of bulk Ag2S is 1.0 eV. The redshift of absorption edge for FTO/TiO2/Ag2S electrodes with prolonged t p indicates the fact that the size of Ag2S QDs gradually increases, and the quantization effect of ultrasmall QDs gradually vanishes. The enhanced absorbance is due to the increased amount of deposited Ag2S QDs. Figure 6 UV–vis absorption spectra of FTO/TiO 2 electrode (a) and FTO/TiO 2 /Ag 2 S electrodes with different photoreduction times (b, c, d, e). Figure 7 shows J-V characteristics of solar cells fabricated with different photoanodes under AM 1.5 illumination at 100 mW/cm2. The photovoltaic properties of these cells are listed in Table 1. TiO2/Ag2S click here cell with

t p = 3 min possesses a much higher J sc and a decreased V oc compared with bare TiO2 solar cell. The increased J sc value is attributed to the sensitization of TiO2 by Ag2S QDs, while the slightly decreased V oc value is mainly due to the band bending between Ag2S QDs and TiO2. With t p increasing from 3 to 10 min, the J sc is promoted from 4.15 to 10.25 mA/cm2. The improved J sc value is caused by an increasing loading amount of Ag2S QDs and a broaden absorption spectrum (as shown in Figure 6). Meanwhile, the V oc values are slightly improved, which is probably due to electron accumulation within TiO2 shifting the Fermi level to more negative potentials. The optimal solar cell performance is obtained with a η of 0.98% and a superior J sc of 10.25 mA/cm2 when t p = 10 min.