Wei-Yun Cheng

Cu2O-Decorated Mesoporous TiO2 Beads as a Highly Efficient Photocatalyst for Hydrogen Production

Cu2O‐decorated mesoporous TiO2 beads (MTBs) are developed as a low‐cost, highly efficient photocatalyst for H2 production. MTBs with a high specific surface area of 189 m2 g−1, a large pore volume of 0.43 cm3 g−1 and a suitable pore size of 8.9 nm are decorated with band‐structure‐matched Cu2O nanocrystals through a simple, fast and low‐cost chemical bath deposition process. The Cu2O nanocrystals serve as an electron–hole separation centre to promote H2 evolution. Under optimal operation conditions, an ultra‐high specific H2 evolution rate of 223 mmol h−1 g−1 is achieved. The success is attributed to the structural advantages of the MTBs of high specific surface areas, large pore volumes and suitable pore sizes together with the much improved electron–hole separation and light utilisation of the Cu2O‐decorated MTBs. The H2 evolution rates achieved with the Cu2O‐decorated MTBs are one order of magnitude higher than those achieved by commercial P25 TiO2.

Ultralow overpotentials for oxygen evolution reactions achieved by nickel cobaltite aerogels

An ultralow overpotential of 0.184 V at 100 mA cm−2 for oxygen evolution reactions in an alkaline solution, 1 M KOH at 25 °C, is achieved by nickel cobaltite aerogels. The success is attributed to the structural advantages of the aerogel materials, including high specific surface areas and a well-connected three-dimensional through-pore structure.

Growth of zirconia and yttria-stabilized zirconia nanorod arrays assisted by phase transition

Well-aligned, densely distributed ZrO2 nanorod arrays were fabricated using a non-catalytic, template-free metal–organic chemical vapour deposition process at a reaction temperature of 1000 °C. The reaction temperature was found to play a key role in product morphology, with particle thin films obtained at 550 °C and nanorod arrays produced at 1000 °C. Increasing the reaction temperature led to the emergence of the medium-temperature tetragonal phase from the dominant low-temperature monoclinic phase, which is advantageous for anisotropic growth necessary for the nanorod formation. With the same deposition process, yttria-stabilized zirconia nanorod arrays of polycrystalline cubic phase were fabricated by co-feeding the dopant precursor, YCl3, with the zirconia precursor, Zr(C5H7O2)4. The present work demonstrated the first example of monoclinic to tetragonal phase-transition assisted one-dimensional (1D) growth, and the concept can be extended to the formation of 1D nanostructures of materials possessing the monoclinic-tetragonal polymorphism.

Nanowires improved charge separation and light utilization in metal-oxide solar cells

The power conversion efficiencies of electrodeposited Cu2O/ZnO p-n junction based solar cells are significantly improved by sandwiching a layer of spin-coated CdS nanowires (NWs) in between the electrochemically deposited Cu2O and ZnO layers. With the inclusion of the CdS NWs, there is observed a 5 fold improvement in the conversion efficiency, from 0.12% to 0.6%, as compared with that of the plain Cu2O/ZnO cell. The improvement is attributed to the enlarged p-n interface area and enhanced light harvesting, charge separation, and electron transport made possible by incorporating the single crystalline, relatively low band gap CdS NWs.

Differential Sensing of Serine and Tyrosine with Aligned CdS Nanowire Arrays Based on pH-Dependent Photoluminescence Behavior

The differential sensing of tyrosine and serine is achieved with well-aligned CdS nanowire arrays by exploring the pH-dependent photoluminescence behavior of the nanowire arrays toward exposure to the two amino acid solutions. The contrasting trend in photoluminescence (PL) intensity with respect to variations in analyte concentration observed at pH 11 served as the check point for the present differential sensing. The application format of the nanowire array is better suited for further sensing device assembly than that of nanocrystal suspensions.