Graphene exfoliation in organic solvents and switching solubility in aqueous media with the aid of amphiphilic block copolymers.

The successful exfoliation of graphite to graphene sheets in liquid phase via tip sonication was achieved. A number of solvents were examined for several time periods and it was found that o-dichlorobenzene (o-DCB) and N-methyl-1,2-pyrolidone (NMP) are ideal solvents to exfoliate graphite and produce stable 10 dispersions of graphene. The exfoliated graphene dispersions were characterized by complementary techniques including AFM, DLS, TGA and Raman. Furthermore, treatment of stable dispersions of exfoliated graphene sheets in NMP with poly[styrene-b-(2-vinylpyridine)] block copolymer, under acidic conditions, resulted on aqueous solubilization of graphene. Similar results were obtained, i.e. transfer of graphene from the organic to the aqueous phase, when poly(isoprene-b-acrylic acid) block copolymer was 15 added on exfoliated graphene in NMP

Self-assembled core-shell CdTe/Poly(3-hexylthiophene) nanoensembles as novel donor−acceptor light-harvesting systems

The self-assembly of novel core-shell nanoensembles consisting of regioregular poly(3-hexylthiophene) nanoparticles (P3HTNPs) of 100 nm as core and semiconducting CdTe quantum dots (CdTeQDs) as shell with a thickness of a few tens of nanometres was accomplished by employing a re-precipitation approach. The structure, morphology and composition of CdTeQDs/P3HTNPs nanoensembles were confirmed by high-resolution scanning transmission microscopy and dynamic light scattering studies. Intimate interface contact between the CdTeQDs shell and the P3HTNPs core leads to the stabilization of the CdTeQDs/P3HTNPs nanoensemble as probed by steady-state absorption spectroscopy. Effective quenching of the characteristic photoluminescence of CdTeQDs at 555 nm, accompanied by simultaneous increase of emission of P3HTNPs at 660 and 720 nm, reveals photoinduced charge-transfer processes. Probing the redox properties of films of CdTeQDs/P3HTNPs further proves the formation of a stabilized core-shell system in the solid-state. Photoelectrochemical assays on CdTeQDs/P3HTNPs films show a reversible on-off photoresponse at a bias voltage of +0.8 V with a three times increased photocurrent compared to CdTeQDs. The improved charge separation is directly related to the unique core-shell configuration, in which the outer CdTeQDs shell forces the P3HTNPs core to effectively act as electron acceptor. The creation of novel donor-acceptor core-shell hybrid materials via self-assembly is transferable to other types of conjugated polymers and semiconducting nanoparticles. This work, therefore, opens new pathways for the design of improved optoelectronic devices.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642742. AMB and WKM gratefully acknowledge financial support from Spanish MINECO under project ENE206-79282-C5-1-R and its associated European Regional Development Fund, as well as the Government of Aragon under project DGA-T66 and associated European Social Fund. RA gratefully acknowledges financial support from Spanish MINECO under project MAT2016 79776-P and its associated European Regional Development Fund, as well as the Government of Aragon under project DGA-E26 and associated European Social Fund. The STEM studies were conducted at the Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon Universidad de Zaragoza, Spain. The authors would like to thank Esteban Urriolabeitía for carrying out the NMR studies.Peer reviewe

All-Carbon Nanosized Hybrid Materials: Fluorescent Carbon Dots Conjugated to Multiwalled Carbon Nanotubes

Fluorescent carbon dots (CDs) were synthesized by following a hydrothermal route in which butane-1,4-diamine and maleic acid were employed in a Teflon autoclave reactor. The structure and morphology of the so-formed spherically shaped CDs were confirmed by a combination of spectroscopic and imaging techniques, such as NMR, ATR-IR, DLS, XRD, and HR-TEM. Additionally, it was found that raw CDs possess numerous −NH₂ functionalities located in their external periphery, responsible for their enhanced aqueous solubility as well as the excellent dissolution CDs showed in polar protic solvents. Moreover, these −NH₂ units were utilized for covalently associating CDs with oxidized multiwalled carbon nanotubes (MWCNTs) yielding robust CDs–MWCNTs hybrids. Based on photoluminescence spectroscopy, electronic communications between the individual components of CDs–MWCNTs were evidenced by the quantitative quenching of the emission of CDs in the presence of MWCNTs as well as the shortening of the photoluminescence lifetime of CDs from 7.3 ns for raw CDs to 300 ps for CDs–MWCNTs. Finally, the redox properties of CDs–MWCNTs were evaluated by electrochemistry measurements, allowing to determine the electrochemical band gap of the hybrid material to be 1.2 eV

Correction to “Combining Dithienosilole-Based Organic Dyes with a Brookite/Platinum Photocatalyst toward Enhanced Visible-Light-Driven Hydrogen Production”

Correction to “Combining Dithienosilole-Based Organic Dyes with a Brookite/Platinum Photocatalyst toward Enhanced Visible-Light-Driven Hydrogen Production