Suchergebnisse

We have deposited 4-aminophenol on Pt(111) surfaces in ultra-high vacuum and studied the strength of its adsorption through a combination of STM, LEED, XPS and ab initio calculations. Although an ordered (2√3 × 2√3)R30° phase appears, we have observed that molecule–substrate interaction dominates the adsorption geometry and properties of the system. At RT the high catalytic activity of Pt induces aminophenol to lose the H atom from the hydroxyl group, and a proportion of the molecules lose the complete hydroxyl group. After annealing above 420 K, all deposited aminophenol molecules have lost the OH moiety and some hydrogen atoms from the amino groups. At this temperature, short single-molecule oligomer chains can be observed. These chains are the product of a new reaction that proceeds via the coupling of radical species that is favored by surface diffusion. ; We acknowledge funding from the Spanish MINECO (Grants MAT2014-54231-C4-1-P, MAT2014-54231-C4-4-P and MAT2013-47898-C2-2-R), the EU via the ERC-Synergy Program (Grant ERC-2013-SYG-610256 NANOCOSMOS), and computing resources from CTI-CSIC. MKS and GOI acknowledge financial support from FCT (Grant No. PTDC/CTM-NAN/121108/2010 and SFRH/BPD/90562/2012), Ministry of Science and Technology, Portugal. HJS would like to acknowledge the MICINN for a "Ramón y Cajal" Senior Research Fellowship, Spain. JIM acknowledges funding from both the CSIC-JAE-Doc Fellowship Program (co-funded by the European Social Fund). The research leading to these results has received funding from the European Union Seventh Framework Programme under Grant agreement No. 604391 Graphene Flagship. ; Peer reviewed

Graphene functionalization with organics is expected to be an important step for the development of graphene-based materials with tailored electronic properties. However, its high chemical inertness makes difficult a controlled and selective covalent functionalization, and most of the works performed up to the date report electrostatic molecular adsorption or unruly functionalization. We show hereafter a mechanism for promoting highly specific covalent bonding of any amino-terminated molecule and a description of the operating processes. We show, by different experimental techniques and theoretical methods, that the excess of charge at carbon dangling-bonds formed on single-atomic vacancies at the graphene surface induces enhanced reactivity towards a selective oxidation of the amino group and subsequent integration of the nitrogen within the graphene network. Remarkably, functionalized surfaces retain the electronic properties of pristine graphene. This study opens the door for development of graphene-based interfaces, as nano-bio-hybrid composites, fabrication of dielectrics, plasmonics or spintronics. ; The research leading to these results has received funding from the Spanish MINECO (through Grants No. MAT2014-54231-C4-1-P, MAT2016-80394-R, RYC-2014-16626 and RYC-2015-17730), from the EU via the ERC-Synergy Program (Grant No. ERC-2013-SYG-610256 Nanocosmos) and the European Union Seventh Framework Program (Grant No. 604391 Graphene Flagship), and from the Comunidad Autónoma de Madrid (CAM) via the MAD2D-CM Program (Grant No. S2013/MIT-3007). We also thank the computing resources from CTI-CSIC. R.L. acknowledges financial support from Spanish MINECO under Grant agreement No. CONSOLIDER INGENIO CSD2009-00013. ; Peer reviewed

Technologically useful and robust graphene-based interfaces for devices require the introduction of highly selective, stable, and covalently bonded functionalities on the graphene surface, whilst essentially retaining the electronic properties of the pristine layer. This work demonstrates that highly controlled, ultrahigh vacuum covalent chemical functionalization of graphene sheets with a thiol-terminated molecule provides a robust and tunable platform for the development of hybrid nanostructures in different environments. We employ this facile strategy to covalently couple two representative systems of broad interest: metal nanoparticles, via S–metal bonds, and thiol-modified DNA aptamers, via disulfide bridges. Both systems, which have been characterized by a multitechnique approach, remain firmly anchored to the graphene surface even after several washing cycles. Atomic force microscopy images demonstrate that the conjugated aptamer retains the functionality required to recognize a target protein. This methodology opens a new route to the integration of high-quality graphene layers into diverse technological platforms, including plasmonics, optoelectronics, or biosensing. With respect to the latter, the viability of a thiol-functionalized chemical vapor deposition graphene-based solution-gated field-effect transistor array was assessed. ; This work was supported by the European Union's Horizon 2020 research and innovation programme under grant agreement No 696656 (Graphene Flagship-core 1) and no 785219 (Graphene Flagship −core 2); UE FP7 ideas: ERC (grant ERC-2013-SYG-610256 Nanocosmos) and Spanish MINECO grants MAT2014-54231-C4-1-P, MAT2014-54231-C4-4-P, MAT2017-85089-C2-1-R, MAT2014-59772-C2-2-P, and BIO2016-79618-R (funded by EU under the FEDER programme), as well as the Nanoavansens program from the Community of Madrid (S2013/MIT-3029). This work has made use of the Spanish ICTS Network MICRONANOFABS partially supported by MINECO and also the ICTS NANBIOSIS, more specifically the Micro-Nano Technology Unit of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the IMB-CNM. We are grateful to Matthias Muntwiler for his assistance with experiments in the PEARL beamline in the SLS facility. Finally, we acknowledge the TEM and ICP services at the CNB and ICMM institutes, respectively. CSS acknowledges the MINECO for a Juan de la Cierva Incorporación grant (IJCI-2014-19291). M. Marciello is grateful to the Comunidad de Madrid (CM) and European Social Fund (ESF) for supporting her research work through the I+D Collaborative Programme in Biomedicine NIETO-CM (B2017-BMD3731). ; Peer reviewed