Heteroatomic Ni, Sn Clusters-Grafted Anatase TiO₂ Photocatalysts: Structure, Electron Delocalization, and Synergy for Solar Hydrogen Production

Abstract

This work shows the molecular engineering of metal active sites on the surface of anatase nanoparticles, based on the fundamental of metal-to-metal charge transfer (MMCT). A series of Sn, Ni-co-modified TiO 2 photocatalysts were prepared by use of surface organometallic chemistry. Photocatalytic hydrogen production from ethylenediaminetetraacetic acid disodium salt solution as a model reaction was used to evaluate the photocatalytic properties of the materials. The chemical states of the modifiers were characterized by a combination of various spectroscopic techniques. These results clearly reveal the synergy of atomically isolated Ni and Sn centers for solar-tohydrogen conversion. A near 10-fold enhancement of hydrogen production is achieved on Sn, Ni-co-grafted TiO 2 photocatalysts under solar light irradiation. Detailed characterization suggests that the synergy is closely related to the [−O−Ti−O−Sn−O−Ni−O−Ti−] heteroatomic clusters with the eight-member cyclic structure. An electron-delocalization loop is proposed for efficient separation of charges photogenerated in bulk TiO 2 and excitons generated in Ni−O−Ti molecular linkages.

Effect of Nitrogen Doping Level on the Performance of N‐Doped Carbon Quantum Dot/TiO2 Composites for Photocatalytic Hydrogen Evolution

“…Figure shows that under full‐spectrum illumination, the photocurrent for NCDs‐ 3 /P25 during on/off cycles reached 0.89 mA cm −2 , four times higher than that of pristine P25 (0.21 mA cm −2 ) and also better than those of NCDs‐ 1 /P25 and NCDs‐ 2 /P25 (0.58 mA cm −2 and 0.77 mA cm −2 , respectively). The high photocurrents (with good reproducibility) detected for the NCDs/P25 composites can be attributed to enhanced charge separation in photoexcited P25 . Transient photocurrent spectra obtained under visible‐light ( λ >450 nm) excitation showed the same trend seen in the photocatalytic H 2 evolution tests (Figure S4), with no detectable photocurrent observed for pristine P25, whereas the NCDs/P25 composites all displayed a photocurrent that increased in proportion to the N‐doping level in the NCDs (i.e., NCDs‐ 3 /P25 showed the highest photocurrent of approximately 0.37 μA cm −2 ).…”

C(sp3)–H Bond Activation by Perovskite Solar Photocatalyst Cell

“…In the HRTEM image, lattice fringes with 0.4, 0.35, and 0.22 nm spacing, corresponding to (011) of FAPbBr 3 and (101) and (001) facets of TiO 2 , respectively, can be identified. 36,37 The optical absorption spectra of FAPbBr 3 /TiO 2 and NiO x / FAPbBr 3 /TiO 2 in Figure 2A reveal two band edges near 420 and 580 nm, which are assigned to TiO 2 and FAPbBr 3 , respectively. 19 Note that the absorption spectra of NiO x , TiO 2 , and FAPbBr 3 are summarized in Figure S7.…”

Highly-dispersed ultrafine Pt nanoparticles on microemulsion-mediated TiO2 for production of hydrogen and valuable chemicals via oxidative photo-dehydrogenation of glycerol

“…S3 provide information about adsorbed species and the presence of hydroxyl groups. The spectra show numerous bands above 3000 cm -1 corresponding mainly to physisorbed water, chemisorbed water and surface titanols, Ti-OH [66][67][68][69]. While the distinct assignment of each band is beyond the scope of this work, it can be seen that: (i) physisorbed water, characterized by very broad bands below 3300 cm -1 can be substantially reduced through thermal pre-treatment, as observed starting at 200 • C; at the same time (ii) most of the strongly chemisorbed water, as testified inter alia, by the broad band around 3400 cm -1 requires thermal treatment beyond 500 • C to be substantially removed from the surface.…”