CdS Rod Based Photocatalyst Towards Overall Water Splitting

Combustion of coal and petroleum emits carbon dioxide and results in seriously environmental problems. Hydrogen energy is cleaner and more powerful than fossil fuel. Pt tipped CdSe@CdS dot-in rod nanostructure could split water into hydrogen under sunlight. The cheap metal nickel, which replaces expensive metal platinum could achieve comparable quantum efficiency of hydrogen generation. Previous study revealed that nickel particle size affected the quantum efficiency due to the different electron transfer time from CdS rod to nickel tip, determined by transient absorbance spectra. The medium size (5 nm) was the best choice in the range of 2~13 nm.

In this project, effect of rod length for nickel tipped CdS rod is planned to be investigated. Rods with different length (20-60 nm) were deposited by nickel particle with similar size (5 nm). Synthesis protocol for depositing nickel are developed. UV-vis absorbance and photoluminescence spectra were performed to characterize light absorbance properties and charge recombination efficiency of series nanostructure. Quantum efficiency of hydrogen generation will be evaluated and charge migration and transfer dynamics will be studies via transient absorbance spectra.

In addition, towards overall water splitting, except for hydrogen generation on platinum tip, metal oxide Co₃O₄ is adopted to connect with dot-in-rod CdSe@CdS nanostructure to generate oxygen. Modular protocol was employed to synthesize the four components catalyst. Different morphology was obtained via control of Co₃O₄-CdSe amount.

In this project, synthesis protocol of rod, metal deposition and metal oxide connection will be developed, charge dynamics will be studied. Both of them are beneficial for nano material synthesis and excellent catalysts.