The engineering of acetylenic carbon-rich nanostructures has great potential in many applications, such as nanoelectronics, chemical sensors, energy storage, and conversion, etc. Here we show the synthesis of acetylenic carbon-rich nanofibers via copper-surface-mediated Glaser polycondensation of 1,3,5-triethynylbenzene on a variety of conducting (e.g., copper, graphite, fluorine-doped tin oxide, and titanium) and non-conducting (e.g., Kapton, glass, and silicon dioxide) substrates. The obtained nanofibers (with optical bandgap of 2.51 eV) exhibit photocatalytic activity in photoelectrochemical cells, yielding saturated cathodic photocurrent of ca. 10 µA cm−2 (0.3–0 V vs. reversible hydrogen electrode). By incorporating thieno[3,2-b]thiophene units into the nanofibers, a redshift (ca. 100 nm) of light absorption edge and twofold of the photocurrent are achieved, rivalling those of state-of-the-art metal-free photocathodes (e.g., graphitic carbon nitride of 0.1–1 µA cm−2). This work highlights the promise of utilizing acetylenic carbon-rich materials as efficient and sustainable photocathodes for water reduction
21 January 2018 in The Journal of Physical Chemistry C
The cation disorder in Cu2ZnSnS4 thin films grown by flash evaporation of ZnS, CuS and SnS binary compounds has been studied by Raman spectroscopy. Process parameters such as the substrate temperature during the evaporation and the Ar pressure in the post-thermal treatment determined the samples' composition and Raman spectra. As a measure of cation disorder, the half-width and relative intensity of the Raman band peaking at 331-332 cm-1 is analysed. Comparison of the spectra for different samples of known composition showed that the relative intensity of the 331 cm-1 defect peak correlates with the previously reported theoretical prediction about enhancement of antisite defect formation in Cu2ZnSnS4 under "Cu-poor, Zn-rich" conditions. For "Cu-rich, Zn-poor" films, further experimental confirmation was obtained of the previously detected effect of the enhancement of cation disorder under intense optical excitationThis research is supported by the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Program FP7/2007-2013/ under REA grant greement 269167 (PVICOKEST), the Spanish MINECO project (KEST- PV, ENE2010-21541-C03) and the OPTEC grant. RC acknowledges financial support from Spanish MINECO within the program Ramon y Cajal (RYC-2011-08521
The results of a resonant Raman scattering (RRS) study of polymer-stabilized colloidal CdSe nanoparticles (NPs) are reported. The size-selective nature of the RRS is demonstrated by analysing the NP ensembles with different average size [Formula: see text] and size distribution Δd using a set of excitation wavelengths. The effect of size selection on the estimation of [Formula: see text] and Δd values from the RRS spectra is discussed, as well as some peculiarities of RRS on surface optical phonons. From the experimentally observed small variation of the I(2LO)/I(LO) ratio for 2-5 nm NPs a minor effect of [Formula: see text] on the electron-phonon coupling strength in this [Formula: see text] range is supposed.