Semiconductor Nanomaterials in Photocatalytic Bipyridine Reduction and H 2 Generation

Semiconductor Nanomaterials in Photocatalytic Bipyridine Reduction and H2 Generation By Li Yu Semiconductor nanoparticles have been used in the study of proton coupled electron transfer from CdS quantum dots (QDs) to N-heptyl-4,4’-bipyridinium (bPYD) and photocatalytic H2 generation with Pt tipped CdS nanorods (NRs) under alkaline solutions. For the QDs/bPYD system, transient absorption (TA) spectroscopy was carried out to examine the pH dependence and bPYD concentration dependence of the interfacial electron and proton transfer. pH dependence experiments revealed that electron transfer happened prior to proton transfer, with the apparent electron transfer rates stayed unchanged at various pH ranging from 4 to 8. Global fitting of the concentration dependence data showed an intrinsic ET/PT rate of 7.51 ± 0.15 × 10 s at pH 8 and 4.39 ± 0.07 × 10 s at pH 5, confirming the pH independent electron transfer process. For the Pt tipped CdS NRs in photocatalytic H2 generation, hydroxyl anions were utilized as an electron donor for fast and efficient hole removal. An external quantum efficiency of 29.3% and H2 generation rate of 34.9 umol/h was achieved under LED light of 455 nm. Semiconductor Nanomaterials in Photocatalytic Bipyridine Reduction and H2 Generation