Anionic Ligand Assisted Synthesis of 3-D Hollow TiO₂ Architecture with Enhanced Photoelectrochemical Performance

Abstract

Hollow structured materials have shown great advantages for use in photoelectrochemical devices. However, their poor charge transport limits overall device performance. Here, we report a unique 3-D hollow architecture of TiO2 that greatly improves charge transport properties. We found that citric acid (CA) plays crucial roles in the formation of the 3-D hollow architecture. First, CA controls the hydrolysis rate of Ti ions and facilitates surface hydrolysis on templates during hydrothermal synthesis. Second, CA suppresses the growth of the carbon template at the initial reaction stage, resulting in the formation of comparatively small hollow fibers. More importantly, a prolonged hydrothermal reaction with CA enables a hollow sphere to grow into entangled hollow fibers via biomimetic swallowing growth. To demonstrate advantages of the 3-D hollow architecture for photoelectrochemical devices, we evaluated its photoelectrochemical performance, specifically the electrolyte diffusion and electron dynamics, by employing dye-sensitized solar cells as a model device. A systemic analysis reveals that the 3-D hollow architecture greatly improves both the electrolyte diffusion and electron transport compared to those of the nanoparticle and hollow sphere due to the elongated porous hollow morphology as well as the densely interconnected nanoparticles at the wall layer.

Low temperature synthesis of graphene hybridized surface defective hierarchical core–shell structured ZnO hollow microspheres with long-term stable and enhanced photoelectrochemical activity

“…It is known that photoelectrochemical activity of a material could depend on several factors such as microstructure, crystallinity, surface area, porosity. 5,40 For a photoelectrochemical reaction, the hierarchical porous structure having large surface area and interconnected mesopores with narrow pore size distribution (Fig. 5 and Table 1) could provide large number of active sites for ionic diffusion and mass transportation.…”

“…[1][2][3][4] In this respect, hollow micro/ nanostructures of metal oxide semiconductors are fascinating owing to their high surface-to-volume ratio, surface permeability and light harvesting properties 3,4 that can offer a wide range of applications including photoelectrochemical (PEC) water splitting, photocatalysis etc. [3][4][5][6][7][8] However, the properties especially textural properties (like surface area, pore size, pore volume) as well as light harvesting capabilities can further be improved in core-shell structured hollow microspheres (CSHM) due to the presence of inner solid core structure. 9,10 This property of CSHM can make them advanced photo anode materials for efficient PEC water splitting.…”

Titanium Dioxide Microsphere-Derived Materials for Solar Fuel Hydrogen Generation

“…Over the past several decades, great developments have also been made in the synthesis and application of TiO 2 microsphere-derived nanocomposites using the hard template method. ,− Song et al employed the hard template (polystyrene) method to successfully fabricate well-defined nitrogen doped, hollow SiO 2 /TiO 2 hybrid spheres, where triethylamine was used as the nitrogen source. The synthetic approach is proposed in Figure .…”

Integrated Energy Aerogel of N,S-rGO/WSe2/NiFe-LDH for Both Energy Conversion and Storage

“…Thus, recent years witnessed extensive initiatives dedicated to developing highly efficient, economical, and earth-abundant electocatalysts for HER and OER. Of the catalysts available today, transition-metal dichalcogens (TMDs), such as MoS 2 , MoSe 2 , WS 2 , and WSe 2 , have great electrocatalytic activity for HER in acidic electrolytes, − while transition-metal-layered double hydroxides (LDHs) demonstrate fair activity and stability for OER in basic electrolytes. − Moreover, the act of hybridizing heteroatom-doped graphene with HER or OER catalysts represents a recent school of thought that could further enhance electrocatalytic performance by effectively combining reaction kinetics. , Heteroatom-doped graphene-based nanocomposites have been used for supercapacitor applications as well. , Such graphene-based nanocomposites have the potential to ameliorate energy storage devices by leveraging the ample specific surface area of graphene and Faradaic redox reactions of TMDs or LDHs. − Despite the progress investigating graphene-based nanocomposites as electrocatalysts achieved to date, the overall performance of the composite electrodes needs to be optimized to be comparable to commercially available electrode materials. Furthermore, the electrode materials for HER or OER are disparate, usually only working well under acidic or basic medium.…”