Tandem Structure of QD Cosensitized TiO₂ Nanorod Arrays for Solar Light Driven Hydrogen Generation

One-dimensional (1D) TiO₂ nanorod arrays as photoelectrode have great potential for solar photoelectrochemical (PEC) hydrogen generation. However, the large band gap and Ti-growth unit preference of rutile TiO₂ limit its solar light utilizing and multijunction nanostructure photoelectrode design. This paper presents a double-sided tandem structure for quantum dot cosensitized photoelectrodes with excellent solar PEC hydrogen generation. TiO₂ nanorod arrays were grown directly on transparent and conductive glass substrates by hydrothermal method and then coated with CdS or CdSe as photosensitizer to extend successfully their photoresponse to visible light. Given the transparent substrate, TiO₂ nanorod arrays could be grown on both sides, allowing the formation of the tandem structure of cosensitized CdS and CdSe with high reactivity under visible light. The double-sided CdS and CdSe cosensitized 1D TiO₂ photoelectrode exhibited the highest solar-to-hydrogen conversion efficiency of 2.78% and pronounced enhancement of simulated photoconversion efficiency. This success in fabricating a double-sided tandem structure 1D TiO₂ photoelectrode provides the opportunity for composite material design based on different band gaps, and this photoelectrode could be applied to other PEC applications

X-ray Absorption Spectroscopic Study on Interfacial Electronic Properties of FeOOH/Reduced Graphene Oxide for Asymmetric Supercapacitors

[[abstract]]The effects of growth time and interface between the iron oxyhydroxide (FeOOH) and carbon materials (carbon nanotubes (CNT) and reduced graphene oxide (RGO)) to form an asymmetric supercapacitor was studied by X-ray absorption spectroscopy (XAS) and electrochemical measurements. FeOOH/CNT (FCNT) and FeOOH/RGO (FRGO) were successfully synthesized by a simple spontaneous redox reaction with FeCl3. The RGO functions as an ideal substrate, providing rich growth sites for FeOOH, and it is believed to facilitate the transport of electrons/ions across the electrode/electrolyte interface. FRGO has been identified as a supercapacitor and found to exhibit significantly greater capacitance than FCNT. To gain further insight into the effects of growth times and the interface of FeOOH for FCNT and FRGO, the electronic structures of FCNT and FRGO with various FeOOH growth times were elucidated by XAS. The difference between the surface electronic structures of CNT and RGO yields different nucleation and growth rates of FeOOH of FeOOH. RGO with excellent interface properties arises from a high degree of covalent functionalization, and/or defects make it favorable for FeOOH growth. FRGO is therefore a promising electrode material for use in the fabrication of asymmetric supercapacitors. In this work, coupled XAS and electrochemical measurements reveal the electronic structure of the interface between FeOOH and the carbon materials and the capacitance performance of asymmetric supercapacitors, which are very useful in the fields of nanomaterials and nanotechnology, especially for their applications in storing energy[[notice]]補正完