Hybrid graphene (Gr)–quantum dot (QD) photodetectors have shown ultrahigh photoresponsivity combining the strong light absorption of QDs with the high mobility of Gr. QDs absorb light and generate photocarriers that are efficiently transported by Gr. Typically, hybrid PbS–QD/graphene photodetectors operate by transferring photogenerated holes from the QDs to Gr while photoelectrons stay in the QDs inducing a photogating mechanism that achieves a responsivity of 6 × 107 A W−1. However, despite such high gain, these systems have poor charge collection with quantum efficiency below 25%. Herein, a ZnO intermediate layer (PbS‐QD/ZnO/Gr) is introduced to improve charge collection by forming an effective p‐n PbS‐ZnO junction driving the electrons to the ZnO layer and then to Gr. This improves the photoresponsivity of the devices by nearly an order of magnitude with respect to devices without ZnO. Charge transfer to Gr is demonstrated by monitoring the change in Fermi level under illumination for conventional PbS‐QD/Gr and for ZnO intermediate PbS‐QD/ZnO/Gr devices. These results improve the capabilities of hybrid QD/Gr configurations for optoelectronic devices.

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High charge collection efficiency in Vis and NIR using intercalated QD/Gr systems.

Binderless carbon-based anode films can enhance the energy density of lithium-ion batteries; however, a major challenge is their long-term electrochemical performance stability. Herein we report ultrathin binderless anodes based on synthesized stacks of reduced multilayer graphene-oxide and silicon nanowires. A key innovation in this work is that instead of using grapheneoxide films based on disordered graphene flakes derived from chemical exfoliation, we produce large and well-ordered sheets of multilayer reduced graphene oxide by chemical vapor deposition, resulting in stronger graphene multilayers with thicknesses of ∼700 nm. The binderless anodes are prepared by building a stack of chemical vapor deposition multilayer graphene oxide with a radiofrequency-sputtered silicon coating followed by thermal annealing for the simultaneous reduction of graphene and silicon nanowire growth. This novel composition results in ∼5 μm ultrathin anodes with a specific capacity of 2247 mAh/g and a capacity retention of 842 mAh/g after 90 cycles.

Herein, we present an electrochemical functionalization strategy for high quality single-layer and multilayer chemical vapor deposited (CVD) graphene directly on a Si/SiO 2 chip facilitating electronic interfacing. This method avoids oxidation and tearing of graphene basal planes. We demonstrate effective functionalization by D-(+)-biotin (Bio), 4-(phenyldiazenyl)-aniline (Dz), and gallic acid (Gall) using cyclic voltammetry. Raman spectroscopy and XPS are used to demonstrate effective functionalization. In order to evaluate the effect of the electrochemical functionalization on graphene properties, DC electrical conductivity, XPS, mobility, and carrier density analysis are presented. We show that this functionalization strategy does not degrade graphene mobility (10 3 cm 2 V −1 s −1 ). After functionalization we observe a rise in Fermi level of ∼0.06 eV. In addition, we prove sensing capabilities with a CVD graphene monolayer on the biotin/avidin system by electrical resistance measurements and electrochemical impedance spectroscopy reaching a detection of 2.5 ng ml −1 . This paper demonstrates an effective strategy to functionalize high quality CVD graphene on a chip compatible with an electronic interface readout.