title: Photocatalytic water reduction using a polymer coated carbon quantum dot sensitizer and a nickel nanoparticle catalyst.
abstract: Hydrogen gas is produced photocatalytically using 470 nm light, PVP-coated carbon quantum dots (CQDs) as the photosensitizer, and nickel nanoparticles (NiNPs) as the catalyst. The effect of the amount of polyvinylpyrrolidone (PVP) on the ability of the CQD/NiNP composites to catalyze proton reduction was studied. A maximum of 330 mmols H2/g CQD is produced using 68 μg ml-1of CQDs and 6 μg ml-1of NiNPs, with activity persisting for 4 h when 20 wt%-PVP-coated CQDs were used. The H2production quantum yield under these conditions is 6%. It was found that composites having higher weight percent PVP had decreased rates of H2production, but increased duration. Increasing the weight percent of PVP coating also increases the fluorescence quantum yield of CQDs. Fluorescence quenching titrations reveal that H2production could occur by either a reductive or oxidative quenching mechanism. The nanomaterials, prepared using simple methods, are used as the photosensitizer and catalyst in the proton reduction system that operates using visible light.
authors.affiliation: Department of Chemistry, Portland State University, Portland, OR 97201, United States of America.
authors.forename: C N
authors.initials: CN
authors.lastname: Virca
authors.forename: H M
authors.initials: HM
authors.lastname: Winter
authors.forename: A M
authors.initials: AM
authors.lastname: Goforth
authors.forename: M R
authors.initials: MR
authors.lastname: Mackiewicz
authors.forename: T M
authors.initials: TM
authors.lastname: McCormick