Electrospun Hierarchical TiO₂ Nanorods with High Porosity for Efficient Dye-Sensitized Solar Cells

Ultraporous anatase TiO₂ nanorods with a composite structure of mesopores and macropores fabricated via a simple microemulsion electrospinning approach were first used as photoanode materials for high-efficiency dye-sensitized solar cells (DSSCs). The special multiscale porous structure was formed by using low-cost paraffin oil microemulsion droplets as the soft template, which can not only provide enhanced adsorption sites for dye molecules but also facilitate the electrolyte diffusion. The morphology, porosity, and photovoltaic and electron dynamic characteristics of the porous TiO₂ nanorod based DSSCs were investigated in detail by scanning electron microscopy (SEM), N₂ sorption measurements, current density–voltage (<i>J</i>–<i>V</i>) curves, UV–vis diffuse reflectance spectra, electrochemical impedance spectroscopy (EIS), intensity modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS), and open-circuit voltage decay (OCVD) measurements. The results revealed that, although fewer amounts of dyes were anchored on the porous TiO₂ nanorod films, they exhibited stronger light scattering ability, fast electrolyte diffusion, and extended electron lifetime compared to the commercial P25 nanoparticles. A power conversion efficiency of 6.07% was obtained for the porous TiO₂ nanorod based DSSCs. Moreover, this value can be further improved to 8.53% when bilayer structured photoanode with porous TiO₂ nanorods acting as the light scattering layer was constructed. This study demonstrated that the porous TiO₂ nanorods can work as promising photoanode materials for DSSCs

Rational Surface Engineering of Anatase Titania Core–Shell Nanowire Arrays: Full-Solution Processed Synthesis and Remarkable Photovoltaic Performance

The high-performance of a well-aligned 1D nanostructured electrode relies largely on a smart and rational modification with other active nanomaterials. Herein, we present a facile solution-based route to fabricate a well-aligned metal oxide-based core–shell hybrid arrays on TCO substrate. Demonstrated samples included nanowire@nanoparticle (TNW@NP) or nanowire@nanosheet (TNW@NS) with a unique porous core/shell nanowire arrays architecture in the absence or presence of DETA during the solvothermal treatment process. The “alcoholysis” and “ripening” growth mechanism is proposed to explain the formation of honeycomb-like nanosheets shell on nanowires core. Based on careful control of experimental condition, a novel double layered TiO₂ photoanode (DL-TNW@NS-YSHTSs) consisting of 16 μm thick TNW@NS under layer and 6 μm thick yolk–shell hierarchical TiO₂ microspheres (YSHTSs) top layer can be obtained, exhibiting an impressive PCE over 10% at 100 mW cm^–2, which can be attributed to the well-organized photoanode composed of hierarchical core–shell arrays architecture and yolk–shell hollow spheres architecture with synergistic effects of high dye loading and superior light scattering for prominent light harvesting efficiency

Trilayered Photoanode of TiO₂ Nanoparticles on a 1D–3D Nanostructured TiO₂‑Grown Flexible Ti Substrate for High-Efficiency (9.1%) Dye-Sensitized Solar Cells with Unprecedentedly High Photocurrent Density

An engineered and optimized trilayered TiO₂ photoelectrode on Ti metal substrates with synergistic effects for dye-sensitized solar cells has been developed through the combination of one-dimensional (1D) TiO₂ nanotubes, three-dimensional (3D) TiO₂ hierarchical microsized spheres, as well as zero-dimensional (0D) nanoparticles with a large surface area. The advantages of efficient charge-collection, light-harvesting, as well as high dye-loading capability make it possible to achieve unprecedentedly high short-circuit photocurrent density (17.90 mA cm^–2) under back-side illumination and thus allow us to obtain a power conversion efficiency as high as 9.10%

Multistack Integration of Three-Dimensional Hyperbranched Anatase Titania Architectures for High-Efficiency Dye-Sensitized Solar Cells

An unprecedented attempt was conducted on suitably functionalized integration of three-dimensional hyperbranched titania architectures for efficient multistack photoanode, constructed via layer-by-layer assembly of hyperbranched hierarchical tree-like titania nanowires (underlayer), branched hierarchical rambutan-like titania hollow submicrometer-sized spheres (intermediate layer), and hyperbranched hierarchical urchin-like titania micrometer-sized spheres (top layer). Owing to favorable charge-collection, superior light harvesting efficiency and extended electron lifetime, the multilayered TiO₂-based devices showed greater <i>J</i>_sc and <i>V</i>_oc than those of a conventional TiO₂ nanoparticle (TNP), and an overall power conversion efficiency of 11.01% (<i>J</i>_sc = 18.53 mA cm^–2; <i>V</i>_oc = 827 mV and FF = 0.72) was attained, which remarkably outperformed that of a TNP-based reference cell (η = 7.62%) with a similar film thickness. Meanwhile, the facile and operable film-fabricating technique (hydrothermal and drop-casting) provides a promising scheme and great simplicity for high performance/cost ratio photovoltaic device processability in a sustainable way

Large-Area Synthesis of a Ni₂P Honeycomb Electrode for Highly Efficient Water Splitting

Transition metal phosphides have recently been regarded as robust, inexpensive electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Thus far, tremendous scientific efforts have been applied to improve the catalytic activity of the catalyst, whereas the scale-up fabrication of morphology-controlled catalysts while maintaining their desired performance remains a great challenge. Herein, we present a facile and scalable approach to fabricate the macroporous Ni₂P/nickel foam electrode. The obtained electrocatalyst exhibits superior bifunctional catalytic activity and durability, as evidenced by a low overpotential of 205 and 300 mV required to achieve a high current density of 100 mA cm^–2 for HER and OER, respectively. Such a spray-based strategy is believed to widely adapt for the preparation of electrodes with uniform macroporous structures over a large area (e.g., 100 cm²), which provides a universal strategy for the mass fabrication of high performance water-splitting electrodes

A CsPbBr₃ Perovskite Quantum Dot/Graphene Oxide Composite for Photocatalytic CO₂ Reduction

Halide perovskite quantum dots (QDs), primarily regarded as optoelectronic materials for LED and photovoltaic devices, have not been applied for photochemical conversion (e.g., water splitting or CO₂ reduction) applications because of their insufficient stability in the presence of moisture or polar solvents. Herein, we report the use of CsPbBr₃ QDs as novel photocatalysts to convert CO₂ into solar fuels in nonaqueous media. Under AM 1.5G simulated illumination, the CsPbBr₃ QDs steadily generated and injected electrons into CO₂, catalyzing CO₂ reduction at a rate of 23.7 μmol/g h with a selectivity over 99.3%. Additionally, through the construction of a CsPbBr₃ QD/graphene oxide (CsPbBr₃ QD/GO) composite, the rate of electron consumption increased 25.5% because of improved electron extraction and transport. This study is anticipated to provide new opportunities to utilize halide perovskite QD materials in photocatalytic applications