Opening up a band gap and finding a suitable substrate material are two big challenges for building graphene-based nanodevices. Using state-of-the-art hybrid density functional theory incorporating long-range dispersion corrections, we investigate the interface between optically active graphitic carbon nitride (g-C(3)N(4)) and electronically active graphene. We find an inhomogeneous planar substrate (g-C(3)N(4)) promotes electron-rich and hole-rich regions, i.e., forming a well-defined electron-hole puddle, on the supported graphene layer. The composite displays significant charge transfer from graphene to the g-C(3)N(4) substrate, which alters the electronic properties of both components. In particular, the strong electronic coupling at the graphene/g-C(3)N(4) interface opens a 70 meV gap in g-C(3)N(4)-supported graphene, a feature that can potentially allow overcoming the graphene's band gap hurdle in constructing field effect transistors. Additionally, the 2-D planar structure of g-C(3)N(4) is free of dangling bonds, providing an ideal substrate for graphene to sit on. Furthermore, when compared to a pure g-C(3)N(4) monolayer, the hybrid graphene/g-C(3)N(4) complex displays an enhanced optical absorption in the visible region, a promising feature for novel photovoltaic and photocatalytic applications.

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Increasing concerns about the atmospheric CO2 concentration and its impact on the environment are motivating researchers to discover new materials and technologies for efficient CO2 capture and conversion. Here, we report a study of the adsorption of CO2, CH4, and H2 on boron nitride (BN) nanosheets and nanotubes (NTs) with different charge states. The results show that the process of CO2 capture/release can be simply controlled by switching on/off the charges carried by BN nanomaterials. CO2 molecules form weak interactions with uncharged BN nanomaterials and are weakly adsorbed. When extra electrons are introduced to these nanomaterials (i.e., when they are negatively charged), CO2 molecules become tightly bound and strongly adsorbed. Once the electrons are removed, CO2 molecules spontaneously desorb from BN absorbents. In addition, these negatively charged BN nanosorbents show high selectivity for separating CO2 from its mixtures with CH4 and/or H2. Our study demonstrates that BN nanomaterials are excellent absorbents for controllable, highly selective, and reversible capture and release of CO2. In addition, the charge density applied in this study is of the order of 1013 cm-2 of BN nanomaterials and can be easily realized experimentally. 2013 American Chemical Society. ABSTRACT:Increasing concerns about the atmospheric CO 2 concentration and its impact on the environment are motivating researchers to discover new materials and technologies for efficient CO 2 capture and conversion. Here, we report a study of the adsorption of CO 2 , CH 4 and H 2 on boron nitride (BN) nanosheets and nanotubes (NTs) with different charge states. The results show that the process of CO 2 capture/release can be simply controlled by switching on/off the charges carried by BN nanomaterials. CO 2 molecules form weak interactions with uncharged BN nanomaterials and are weakly adsorbed. When extra electrons are introduced to these nanomaterials (i.e. when they are negatively charged), CO 2 molecules become tightly bound and strongly adsorbed. Once the electrons are removed, CO 2 molecules spontaneously desorb from BN absorbents. In addition, these negatively charged BN nano-sorbents show high selectivity for separating CO 2 from its mixtures with CH 4 and/or H 2 . Our study demonstrates that BN nanomaterials are excellent absorbents for controllable, highly selective, and reversible capture and release of CO 2. In addition, the charge density applied in this study is of the order of 10 13 cm -2 of BN nanomaterials, and can be easily realized experimentally.

Ultrasmall PEGylated Cu Se nanoparticles with strong near-infrared absorption have been prepared by an ambient aqueous method. The resultant water-soluble and biocompatible nanoparticles are demonstrated to be a novel nanotheranostic agent for effective deep-tissue photoacoustic imaging, computed tomography imaging, single-photon emission computed tomography imaging, and photothermal therapy of cancer.

Single‐atom catalysts have demonstrated their superiority over other types of catalysts for various reactions. However, the reported nitrogen reduction reaction single‐atom electrocatalysts for the nitrogen reduction reaction exclusively utilize metal–nitrogen or metal–carbon coordination configurations as catalytic active sites. Here, we report a Fe single‐atom electrocatalyst supported on low‐cost, nitrogen‐free lignocellulose‐derived carbon. The extended X‐ray absorption fine structure spectra confirm that Fe atoms are anchored to the support via the Fe‐(O‐C2)4 coordination configuration. Density functional theory calculations identify Fe‐(O‐C2)4 as the active site for the nitrogen reduction reaction. An electrode consisting of the electrocatalyst loaded on carbon cloth can afford a NH3 yield rate and faradaic efficiency of 32.1 μg h−1 mgcat.−1 (5350 μg h−1 mgFe−1) and 29.3 %, respectively. An exceptional NH3 yield rate of 307.7 μg h−1 mgcat.−1 (51 283 μg h−1 mgFe−1) with a near record faradaic efficiency of 51.0 % can be achieved with the electrocatalyst immobilized on a glassy carbon electrode.