Xin-Zheng Yue,Chuan-Qi Li,Zhong-Yi Liu,Sha-Sha Yi,De-Liang Chen,Feng Wang,Shuai-Hui Li
The constructing of functional materials with well-defined nanostructure , showing efficient charge separation and transportation properties, has been intensively and in depth investigated to fabricate catalysts for H 2 generation from solar-driven water reduction. Here we demonstrate that loading W 2 C@C structure in which each W 2 C nanoparticle (NP) is wrapped by carbon shell on surface of hollow TiO 2 microspheres (HTMs) can enhance the separation of photogenerated electron-hole pairs by building an internal electric field in W 2 C@C/HTMs composite structure and act as the reaction active sites for water reduction. As expected, the optimized W 2 C@C/HTMs construction exhibits the highest photocatalytic H 2 generation rate of 6.91 mmol h −1 g −1 under simulated solar light illumination, over 20 times larger than that of bare HTMs. The underlying mechanism has been investigated from the perspective of photochemistry and photophysics based on a series of characterization techniques, which suggests that W 2 C@C can effectively steer the charge kinetics, maximizing the charge carriers’ separation.
Recently, organo-metal halide perovskite (e.g., CH 3 NH 3 PbI 3 ) solar cells have shown a significant surge in progress and efficiency. The photovoltaic performance of perovskite solar cells (PSC) extensively depends on the morphology of the materials at nano-level, because the intrinsic electrical, optical and electrochemical properties also change with a change in morphology. Different TiO 2 nanostructures with diverse dimensionalities, 0D hollow TiO 2 nanoparticles (HTNPs), 3D hollow TiO 2 mesospheres (HTMSs) and 3D hierarchical TiO 2 spheres (HTSs) were synthesized hydrothermally. The PSCs based on 3D HTSs or 3D HTMSs as electron transport layers (ETLs) shows better performance than the PSCs fabricated with 0D HTNPs as ETL. The enhanced results can be attributed to the better penetration of the perovskite materials in the porous network of the HTSs or HTMSs and decreased interfacial recombination due to superior charge extraction and electron transport at the HTSs/CH 3 NH 3 PbI or HTMSs/CH 3 NH 3 Pb interfaces. By using a self-assembled TiO 2 compact layer (c-TiO 2 ), followed by a mesoporous layer of HTSs, produces PSCs with an excellent efficiency of 15.08%. Such c-TiO 2 -ETL films may improve PSCs performance by enhancing electron extraction and block the photogenerated holes.
We report a novel nanocomposite of hollow TiO2 microspheres and plasma polyacrylic acid (TiO2@PPAA) modified with rhodamine B (TiO2@PPAA-RhB). This nanocomposite was further used as an electrochemical sensor for the ultra-sensitive and selective detection of Cu2+ in water. A gold electrode was modified with hollow TiO2 nanospheres, followed by the closely bonded layer of PPAA via plasma polymerization. Subsequently, the carboxyl groups of TiO2@PPAA nanocomposites were activated to ester groups by N-hydroxysuccinimide/1-ethyl-3-(3-dimethylaminoprolyl) carbodiimide hydrochloride. The resultant activated ester groups reacted with the amino groups on rhodamine to form the amide groups, leading to the modification of TiO2@PPAA nanocomposites with rhodamine. Considering the synergistic effect of strong electrostatic interaction between the carboxyl groups of PPAA and Cu2+, the direct adsorption of Cu2+ on the TiO2 surface, and the coordination chemistry formed between Cu2+ and rhodamine, the developed electrochemical biosensor exhibited high sensitivity of Cu2+ detection, with a detection limit of 0.404 pM within the range of 0.001–10 nM of Cu2+. Therefore, the fabricated electrochemical sensor based on TiO2@PPAA-RhB can be obtained via plasma polymerization and represents a highly promising tool for use in environmental monitoring.
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