RESUMO
Herein, we successfully fabricated an Al-doped α-Ga2O3 nanorod array on FTO using the hydrothermal and post-annealing processes. To the best of our knowledge, it is the first time that an Al-doped α-Ga2O3 nanorod array on FTO has been realized via a much simpler and cheaper way than that based on metal-organic chemical vapor deposition, magnetron sputtering, molecular beam epitaxy, and pulsed laser deposition. And, a self-powered Al-doped α-Ga2O3 nanorod array/FTO photodetector was also realized as a photoanode at 0 V (vs. Ag/AgCl) in a photoelectrochemical (PEC) cell, showing a peak responsivity of 1.46 mA/W at 260 nm. The response speed of the Al-doped device was 0.421 s for rise time, and 0.139 s for decay time under solar-blind UV (260 nm) illumination. Compared with the undoped device, the responsivity of the Al-doped device was ~5.84 times larger, and the response speed was relatively faster. When increasing the biases from 0 V to 1 V, the responsivity, quantum efficiency, and detectivity of the Al-doped device were enhanced from 1.46 mA/W to 2.02 mA/W, from ~0.7% to ~0.96%, and from ~6 × 109 Jones to ~1 × 1010 Jones, respectively, due to the enlarged depletion region. Therefore, Al doping may provide a route to enhance the self-powered photodetection performance of α-Ga2O3 nanorod arrays.
RESUMO
A novel palladium N-heterocyclic bis-carbene dicarboxylate ligand (Pd-NHDC-H2L) was successfully synthesized. In addition, an Pd-NHDC-containing UiO-67 type MOF (UiO-67-Pd-NHDC) was prepared on the basis of a size-matched ligand mixture of biphenyl-4,4'-dicarboxylic acid/Pd-NHDC-H2L (9/1) and ZrCl4 under solvothermal conditions. The obtained UiO-67-Pd-NHC MOF can be a highly heterogeneous catalyst to promote Heck cross-coupling and intermolecular benzyne-benzyne-alkene insertion reactions.
RESUMO
The adsorption of a typical biogenic toxin aflatoxin B1 on montmorillonite modified by low-molecular-weight humic acids (M(r) < 3 500) was investigated. The montmorillonite rapidly adsorbed the aflatoxin B1 until amounting to the maximal capacity, and then the adsorbed aflatoxin B1 slowly released into solution and reached the sorption equilibrium state after 12 h. The sorption isotherm of aflatoxin B1 by montmorillonite could be well described by Langmiur model, while the sorption isotherm by humic acid-modified montmorillonite was well fitted by using the Freundlich model. The modification of the montmorillonite with humic acids obviously enhanced its adsorption capacity for aflatoxin B1, and the amounts of aflatoxin adsorbed by modified montmorillonite were obviously higher than those by montmorillonite. The sorption enhancement by humic acid modification was attributed to (1) the enlarged adsorption sites which owed to the surface collapse of crystal layers induced by organic acids, and (2) the binding of aflatoxin with the humic acid sorbed on mineral surface. In addition, the adsorption amounts of aflatoxin by montmorillonite and modified montmorillonite increased with the increase of pH values in solution, and more significant enhancement was observed for the latter than the former, which attributed to the release of humic acids from the modified montmorillonite with the high pH values in solution. This indicates that increasing the pH values resulted in the enhanced hydrophilic property and the release of the organic acids presented in modified montmorillonite, and more sorption sites were available for aflatoxin on the modified montmorillonite. Results of this work would strengthen our understanding of the behavior and fate of biological contaminants in the environment.
