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2 Esquemas.- 5 Figuras ; A facile strategy for the controllable growth of CdS nanoparticles at the periphery of MoS 2 en route the preparation of electron donor‐acceptor nanoensembles is developed. Precisely, the carboxylic group of α‐lipoic acid, as addend of the modified MoS 2 obtained upon 1,2‐dithiolane functionalization, was employed as anchor site for the in‐situ preparation and immobilization of the CdS nanoparticles in an one‐pot two‐step process. The newly prepared MoS 2 /CdS hybrid material was characterized by complementary spectroscopic, thermal and microscopy imaging means. Absorption spectroscopy was employed to register the formation of MoS 2 /CdS, by observing a broad shoulder centered at 420 nm due to CdS nanoparticles, while the excitonic bands of MoS 2 were also evident. Moreover, based on the efficient quenching of the characteristic fluorescence emission of CdS at 725 nm by the presence of MoS 2 , strong electronic interactions at the excited state between the two species within the ensemble were identified. Photoelectrochemical assays of MoS 2 /CdS thin‐film electrodes revealed a prompt, steady and reproducible anodic photoresponse during repeated on‐off cycles of illumination. A significant zero‐current photopotential of ‐540 mV and an anodic photocurrent of 1 μA were observed, underlining improved charge‐separation and electron transport from CdS to MoS 2 . The superior performance of the charge‐transfer processes in MoS 2 /CdS is of direct interest for the fabrication of photoelectrochemical and optoelectronic devices. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642742. Support of this work by the project "Advanced Materials and Devices" (MIS 5002409) which is implemented under the "Action for the Strategic Development on the Research and Technological Sector", which Submitted_Manuscript is implemented under the "Reinforcement of the Research and Innovation Infrastructures", funded by the Operational Program "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund) is also acknowledged. A.M.B. and W.K.M. acknowledge Spanish MINEICO (project grant ENE2016-79282-C5-1-R, AEI/FEDER, UE) and the Gobierno de Aragón (Grupo Reconocido DGA T03_17R, FEDER, UE). ; Peer reviewed

5 Figuras, 1 Esquema, 1 Tabla .-- Información suplementaria disponible en la página web del editor. ; The preparation of MoS 2 ‐polymer carbon nanodot (MoS 2 ‐PCND) hybrid material was accomplished by employing an easy and fast bottom‐up synthetic approach. Specifically, MoS 2 ‐PCND was realized by the thermal decomposition of ammonium tetrathiomolybdate and the in‐situ complexation of Mo with carboxylic acid units present in the surface of PCNDs. The newly prepared hybrid material was comprehensively characterized by spectroscopic, thermal and electron microscopy imaging means. The electrocatalytic activity of MoS 2 ‐PCND was examined against the hydrogen evolution reaction (HER) and compared with that attributed to the hybrid material prepared by a top‐down approach, namely with MoS 2 ‐PCND(exf‐fun), in which MoS 2 was firstly exfoliated and then covalently functionalized with PCNDs. The MoS 2 ‐PCND hybrid material showed superior electrocatalytic activity against HER with low Tafel slope value and excellent electrocatalytic stability, with an onset potential at ‐0.16 V vs RHE. The superior catalytic performance of MoS 2 ‐PCND was rationalized by considering the catalytic active sites of MoS 2 , the effective charge/energy‐transfer phenomena from PCNDs to MoS 2 and the synergetic effect between MoS 2 and PCNDs within the hybrid material. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 642742. Support of this work by the project "Advanced Materials and Devices" (MIS 5002409) which is implemented under the "Action for the Strategic Development on the Research and Technological Sector", which is implemented under the "Reinforcement of the Research and Innovation Infrastructures", funded by the Operational Program "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Ministry of Development and Investments, Greece, and the European Union (European Regional Development Fund) is also acknowledged. A.M.B. and W.K.M. acknowledge Spanish MINEICO (project grant ENE2016-79282-C5-1-R, AEI/FEDER, UE) and the Gobierno de Aragón (Grupo Reconocido DGA T03_17R, FEDER, UE). The SR-EELS studies were conducted at the Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Spain. The SR-EELS studies were conducted at the Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Spain. R.A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project grant MAT2016-79776-P (AEI/FEDER, UE) from the Government of Aragon and the European Social Fund under the project "Construyendo Europa desde Aragon" 2014-2020 (grant number E13_17R) and from the European Union H2020 programs "ESTEEM3" (823717) and under the "Graphene Flagship" CORE2 project grant agreement No 785219. ; Peer reviewed

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 reviewed