TiO₂ Photoanodes Sensitized with Bi₂Se₃ Nanoflowers for Visible–Near-Infrared Photoelectrochemical Water Splitting

Abstract

Semiconducting photoelectrodes emerge as an efficient platform for converting light energy into hydrogen by photoelectrochemical (PEC) water splitting. The present study reports the improvement in PEC performance using metal oxide photoelectrodes sensitized with a narrow-band-gap semiconductor Bi 2 Se 3 , which extends the light response beyond the visible region and generates and transports charge carriers. When Bi 2 Se 3 nanoflowers (NFs) were incorporated into the TiO 2 electrode, the extent of hydrogen production was found to be increased by an order of magnitude. The binary electrode TiO 2 /Bi 2 Se 3 nanocomposite exhibited a decent photocurrent density of 1.76 mA cm −2 at 1.23 V, which is three times superior to that of pure Bi 2 Se 3 NFs. Moreover, the binary TiO 2 /Bi 2 Se 3 electrode delivers the highest solar-to-hydrogen conversion efficiency of 1.01% at 0.6 V and incident photon-to-current conversion efficiency of 10.5%. Furthermore, both Bi 2 Se 3 and TiO 2 /Bi 2 Se 3 electrodes show superior photostabilities for over 6 h. The enhanced PEC activity is attributable to the facile transportation of photoelectrons from Bi 2 Se 3 to TiO 2 electrodes, thereby minimizing the charge recombination.

Facile Synthesis and Photoelectrochemical Performance of a Bi2S3@rGO Nanocomposite Photoanode for Efficient Water Splitting

“…Furthermore, the X-ray photoelectron spectroscopy (XPS) analysis was carried out to justify the electronic states and the surface chemical structure of the Bi 2 S 3 @rGO composite (Figure ). The high-resolution deconvoluted XPS spectra of Bi 4f (Figure a) show two peaks at 158.7 and 164.0 eV related to the Bi 4f 5/2 and Bi 4f 7/2 , respectively, which correspond to typical Bi 3+ species in Bi 2 S 3 . − As shown in Figure a, two weak peaks located at 161.1 and 162.3 eV, which appeared between Bi 4f peaks belong to S 2p 3/2 and S 2p 1/2 , respectively, and the prominent peak presented at 225.3 eV was assigned to S 2s (Figure b), which confirms the formation of Bi–S species. − The deconvoluted XPS spectra of C 1s (Figure c) exhibit four peaks, where the peak at 284.8 eV corresponds to the C–C/CC bond of the graphitic carbon in graphene, while other three peaks at 285.7, 286.2, and 288.4 eV are due to the existence of variant functional groups on the rGO sheets, namely, C–OH, C–O, and CO, respectively. − Figure d reveals that the deconvoluted O 1s spectrum show two peaks at 532.3 and 535.6 eV, which correspond to CO and O–H, respectively. − An additional peak was observed at 530.3 eV, which further confirms the Bi–O bond in the Bi 2 S 3 @rGO heterostructure. − Therefore, the appearance of Bi, S, C, and O elements confirms the formation of the Bi 2 S 3 @rGO composite. The XPS spectra of Bi 2 S 3 NRs are shown in Figure S2.…”

Plasmonic Au nanoparticle sandwiched CuBi2O4/Sb2S3photocathode with multi-mediated electron transfer for efficient solar water splitting

“…The charge transfer resistance is proportional to the radius of the semicircle. 57,58 As shown in Fig. 8a In principle, the E  for a p-type semiconductor is considered roughly equivalent to the valence band (VB).…”

“…CuBi 2 O 4 -based photo-absorber cathodes for the HER using solar harvesting have been developed in our group and by others, such as Co-doped CuBi 2 O 4 22 and a TiO 2 /Bi 2 Se 3 photoanode-CuBi 2 O 4 photocathode PEC cell. 23 The reported photocurrent densities of pure CuBi 2 O 4 are low, and heterojunction fabrication is an efficient approach to boost the charge separation and broaden the light absorption range and photocurrent densities resulting in improved PEC performance. Wi et al fabricated a CuBi 2 O 4 /ZnSe/P25 heterojunction, which contributed to a higher PEC performance than the prepared CuBi 2 O 4 photoelectrode.…”

TiO2 Nanotubes Architectures for Solar Energy Conversion

“…In this case, the TiO 2 /Bi 2 Se 3 composite (large band gap/small band gap) leads to a photocurrent that much higher than that of TiO 2 , resulting in a photocurrent of 1.76 mA/cm 2 and a solar to hydrogen of~1%. The authors ascribe this enhancement to improved transport from Bi 2 Se 3 to the TiO 2 electrode, resulting in a minimal charge recombination [101].…”