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Spatial separation of dual-cocatalysts on one-dimensional semiconductors for photocatalytic hydrogen production
No full textLight-driven hydrogen production using semiconductor photocatalysts has gained much interest owing to their ability to store sunlight in the form of portable chemical fuel. The spatial separation of dual-cocatalysts onto different surfaces has been considered as a useful strategy for fabricating dynamic particulate photocatalysts to hinder charge recombination and reverse reactions. Herein, using one-dimensional (1D) semiconductors, CdSe nanorods as an example, we experimentally demonstrated that photogenerated electrons and holes can be effectively separated along different directions of a 1D semiconductor. Following this phenomenon, the reduction cocatalyst Pt and oxidation cocatalyst PdS were spatially deposited on different sites via an in situ photodeposition process, which drastically enhanced the photocatalytic activity for hydrogen production to more than 20 times, thus exhibiting an extremely high apparent quantum efficiency (AQE) of similar to 45% at 420 nm. Further studies using photoluminescence spectroscopy indicated that the spatially separated dual-cocatalysts efficiently captured the photogenerated electrons and holes migrating to the surface, which greatly decreased the recombination of charge carriers and consequently led to superior photocatalytic performances. Our work provides an effective strategy for the rational construction of highly efficient photocatalyst systems based on (quasi) 1D semiconductors for artificial solar energy conversion
Surface processes occurring during aqueous phase ethanol reforming on Ru/TiO2 tracked by ATR-IR spectroscopy
No full textSurface processes occurring at the solid-liquid interface of Ru/TiO2 catalysts during aqueous phase reforming of ethanol at reaction conditions (200 degrees C and 20 bar) have been examined using attenuated total reflection infrared spectroscopy (ATR-IR). Depending on the loading and particle size of Ru significant differences in the population dynamics of adsorbed species were observed. On the catalyst with high loading (5 wt%) and large particle size (similar to ca. 4 nm) formation of intermediate acetylide was detected, which is attributed to enhanced C-O bond cleavage promoting methanation and thus leading to lower efficiency of H-2 generation. In contrast, on the catalyst with low loading (0.5 wt%) and smaller particle size (similar to ca. 1 nm) no acetylide was detectable, indicating that C-O bond cleavage was suppressed
One-Step Preparation of Zwitterionic-Rich Hydrophilic Hydrothermal Carbonaceous Materials for Enrichment of N-Glycopeptides
No full textTwo kinds of novel zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) materials decorated with phosphorylcholine or sulfobetaine type zwitterionic groups were facilely synthesized employing hydrothermal carbonization (HTC) reaction, in which sustainable carbohydrate (glucose) could be converted into functionalized carbonaceous materials with strong hydrophilicity using a one-step and environmentally mild process. The properties of obtained materials were characterized by helium ion microscopy (HIM), N-2 adsorption/desorption measurement, static water contact angle measurement, elemental analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and zeta-potential. As a result, 26 N-glycopeptides with S/N above 20 could be detected from 150 fmol IgG digests after hydrophilic interaction chromatography (HILIC) enrichment by using as-synthesized material HTC-Glc-10%MPC. The limit of detection in matrix assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF MS) analysis was as low as 5 fmol and enrichment selectivity reached 100:1. Furthermore, 175 N-glycosylation sites in 285 N-glycopeptides from 92 glycoproteins were identified from 2 mu L of human serum. This work provided a new, simple, and green way to synthesize an N-glycopeptide enrichment material for liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis of glycoproteomes
