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We present a simple in situ self-assembly approach for crafting a heteroatom doped graphene supported metal–organic framework (MOF) nanocomposite, which is a highly conductive redox active 2D platform with excellent potential for selective and sensitive electrochemical sensing of biologically important molecules. The hybrid nanocomposite comprises of 1,4-benzene dicarboxylic acid organic linker based Cu-MOF self-assembled over sulfur doped graphene nanosheets (S-Gr). Our detailed structural characterization and electrochemical investigations carried over the so-crafted Cu-MOF@S-Gr composite suggest that S-Gr sheets, besides inducing a directional growth of MOF crystals, endow this nanohybrid with numerous electroactive sites. The synergism between the Cu-MOF and S-Gr components and the presence of too many electroactive sites facilitate faster heterogeneous electron transfer and mass transfer, thereby imparting Cu-MOF@S-Gr with excellent conductivity, electrocatalytic activity and electroanalytical utility. The excellent electroanalytical utility of the Cu-MOF@S-Gr hybrid nanocomposite was explored toward selective and sensitive sensing of acetaminophen (AC), dopamine (DA) and H2O2. We demonstrate that using the Cu-MOF@S-Gr hybrid nanocomposite, AC and DA can be electrochemically sensed with a resolution of 2.22 and a sensitivity of 0.85 μA μM−1 cm−2 and 0.58 μA μM−1 cm−2 in the concentration ranges of 2 μM to 98 μM and 10 μM to 80 μM with detection limits as low as 12.00 ± 0.05 nM and 37.00 ± 0.06 nM, respectively. We also demonstrate that with the Cu-MOF@S-Gr hybrid, H2O2 can be electrochemically sensed in the concentration range as low as 0.1–3.0 μM with an extremely low detection limit of 11.3 ± 0.04 nM and a very high sensitivity of 63.82 μA μM−1 cm−2. We opine that the present study will stimulate an intense research activity toward the design of highly sensitive, selective and stable MOF based electroanalytical devices. [ABSTRACT FROM AUTHOR]

We report the synthesis of a nano-spinel cobalt decorated sulphur doped reduced graphene oxide (Co@S–rGO) composite exhibiting excellent electrocatalytic performance and electrochemical stability toward oxygen evolution reaction (OER) in an alkaline medium. Moreover, the so crafted noble metal free Co@S–rGO electrocatalyst, well characterized by UV-Vis spectroscopy, FTIR, XRD, SEM, and energy dispersive X-ray spectroscopy, exhibits promising activity toward electrochemical sensing of H2O2. For OER in an alkaline medium, the Co@S–rGO composite exhibits a Tafel slope of ca. 49 mV dec−1, with an overpotential requirement of just 389 mV for a specific current density of 10 mA cm−2. In the OER electrochemical stability tests, the Co@S–rGO electrocatalyst could maintain its peak OER performance for a time span of about 50 000 seconds during chronoamperometric measurements, while in the linear sweep voltammetry records almost negligible difference was observed between the final and the initial scan in a total of 1000 scans recorded over 25 hours for OER over Co@S–rGO. These chronoamperometric and voltammetric observations establish the excellent activity and long-term electrochemical stability of Co@S–rGO for OER in alkaline media. These current/potential and stability parameters observed for the OER performance of the Co@S–rGO composite are far better than that reported for various non-noble metal based state-of-the-art materials specifically crafted for OER. For the electrochemical sensing of H2O2, the Co@S–rGO composite exhibits a limit of detection as low as 23 nM with a sensitivity of 22743.85 μA M−1 cm−2. The excellent OER performance and H2O2 sensing activity of the Co@S–rGO composite can be attributed to the special synergism between the Co and S–rGO components and the extended electrochemically active surface area of Co nanodeposits in this noble metal free electrocatalyst. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate that the catalytic performance of imidazolium-based surface-active ionic liquid (SAIL) micelles can be significantly enhanced through the addition of an appropriate type and amount of intelligently conceived amphiphile to form mixed micelles. Specifically, we show that the catalytic performance of 1-dodecyl-3-methyl imidazolium chloride (DDMIMCl) micelles toward the reductive degradation of rhodamine B (RhB), a carcinogenic dye extensively used in multiple industrial applications, can be appreciably boosted through addition of Brij56, a nonionic surfactant. Detailed kinetic investigations on the catalytic performance of pre- and post-micellar concentrations of DDMIMCl and its mixed micelles with Brij56 over various mole fractions, toward the reductive degradation of RhB, are presented. The data analyzed in light of Berezin's kinetic model suggest that the addition of Brij56 to DDMIMCl micelles significantly enhances their catalytic performance. The catalytic activity exhibited by the DDMIMCl–Brij56 (XBrij56 = 0.2) mixed micellar system is better than that reported for many state-of-the-art nanoparticle/homogenous catalysts. The results explained in light of Berezin's kinetic model are well supported by physico-chemical studies like conductometry, fluorimetry and dynamic light scattering. The presented results anticipate stimulation of extensive research activity for exploiting the mixed micellization approach as a novel avenue for modulating the catalytic performance of SAILs. [ABSTRACT FROM AUTHOR]

A simple strategy for the synthesis of self-assembled gold nanoparticles (AuNPs) on sulphur-doped graphene (S-Gr) to form AuNPs-S-Gr nanohybrids is presented. Structural, chemical and morphological characterization of AuNPs-S-Gr nanohybrids through UV-Vis spectroscopy, the X-ray diffraction technique (XRD), Raman spectroscopy, force field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM) and electrochemical techniques establishes the AuNPs-S-Gr nanohybrid as a monolayer of AuNPs assembled on S-Gr. The lead underpotential deposition experiments ascertain that nano Au in AuNPs-S-Gr nanohybrids is better exposed for faradic processes than in citrate-stabilized AuNPs, with the faradic response in the former being dominated by the Au-(111) planes. The AuNPs-S-Gr nanohybrids are demonstrated to be electrochemically stable, reusable and with an excellent prospect for the sensitive and selective electrochemical detection of two biologically and environmentally important oxides of nitrogen viz. nitrite (NO2−) and nitric oxide (NO). The electrocatalytic electron transfer rate constants (kcat) of the AuNPs-S-Gr nanohybrid towards electro-oxidation of NO2− and NO were observed to be 0.98 (±0.03) × 105 M−1 s−1/2 and 0.51 (±0.02) × 104 M−1 s−1/2, respectively. The AuNPs-S-Gr nanohybrid was demonstrated to ensure selective and sensitive electrochemical quantification of NO2− and NO with a very high sensitivity (20766.17 and 21046.72 μA M−1 cm−2), a wide linear range (12.5–680.92 and 24.9–680.93 μM) and very low detection limits (0.003 and 0.009 μM), respectively. Importantly, the AuNPs-S-Gr nanohybrid exhibited appreciable selectivity towards the detection of NO2− and NO even in the presence of a very high concentration of common interfering ions. The stability and reproducibility of faradic signals for NO2− and NO detection at the AuNPs-S-Gr nanohybrid were found to be excellent for standard laboratory and real samples. The electrocatalytic activity and sensing results of the AuNPs-S-Gr nanohybrid for NO2− and NO are much better than those recently reported over surfaces purposefully designed for electrocatalytic oxidation and electrosensing of these analytes. [ABSTRACT FROM AUTHOR]

We present a simple in situ self-assembly approach for crafting a heteroatom doped graphene supported metal–organic framework (MOF) nanocomposite, which is a highly conductive redox active 2D platform with excellent potential for selective and sensitive electrochemical sensing of biologically important molecules. The hybrid nanocomposite comprises of 1,4-benzene dicarboxylic acid organic linker based Cu-MOF self-assembled over sulfur doped graphene nanosheets (S-Gr). Our detailed structural characterization and electrochemical investigations carried over the so-crafted Cu-MOF@S-Gr composite suggest that S-Gr sheets, besides inducing a directional growth of MOF crystals, endow this nanohybrid with numerous electroactive sites. The synergism between the Cu-MOF and S-Gr components and the presence of too many electroactive sites facilitate faster heterogeneous electron transfer and mass transfer, thereby imparting Cu-MOF@S-Gr with excellent conductivity, electrocatalytic activity and electroanalytical utility. The excellent electroanalytical utility of the Cu-MOF@S-Gr hybrid nanocomposite was explored toward selective and sensitive sensing of acetaminophen (AC), dopamine (DA) and H2O2. We demonstrate that using the Cu-MOF@S-Gr hybrid nanocomposite, AC and DA can be electrochemically sensed with a resolution of 2.22 and a sensitivity of 0.85 μA μM−1 cm−2 and 0.58 μA μM−1 cm−2 in the concentration ranges of 2 μM to 98 μM and 10 μM to 80 μM with detection limits as low as 12.00 ± 0.05 nM and 37.00 ± 0.06 nM, respectively. We also demonstrate that with the Cu-MOF@S-Gr hybrid, H2O2 can be electrochemically sensed in the concentration range as low as 0.1–3.0 μM with an extremely low detection limit of 11.3 ± 0.04 nM and a very high sensitivity of 63.82 μA μM−1 cm−2. We opine that the present study will stimulate an intense research activity toward the design of highly sensitive, selective and stable MOF based electroanalytical devices. [ABSTRACT FROM AUTHOR]

We report the synthesis of a nano-spinel cobalt decorated sulphur doped reduced graphene oxide (Co@S–rGO) composite exhibiting excellent electrocatalytic performance and electrochemical stability toward oxygen evolution reaction (OER) in an alkaline medium. Moreover, the so crafted noble metal free Co@S–rGO electrocatalyst, well characterized by UV-Vis spectroscopy, FTIR, XRD, SEM, and energy dispersive X-ray spectroscopy, exhibits promising activity toward electrochemical sensing of H2O2. For OER in an alkaline medium, the Co@S–rGO composite exhibits a Tafel slope of ca. 49 mV dec−1, with an overpotential requirement of just 389 mV for a specific current density of 10 mA cm−2. In the OER electrochemical stability tests, the Co@S–rGO electrocatalyst could maintain its peak OER performance for a time span of about 50 000 seconds during chronoamperometric measurements, while in the linear sweep voltammetry records almost negligible difference was observed between the final and the initial scan in a total of 1000 scans recorded over 25 hours for OER over Co@S–rGO. These chronoamperometric and voltammetric observations establish the excellent activity and long-term electrochemical stability of Co@S–rGO for OER in alkaline media. These current/potential and stability parameters observed for the OER performance of the Co@S–rGO composite are far better than that reported for various non-noble metal based state-of-the-art materials specifically crafted for OER. For the electrochemical sensing of H2O2, the Co@S–rGO composite exhibits a limit of detection as low as 23 nM with a sensitivity of 22743.85 μA M−1 cm−2. The excellent OER performance and H2O2 sensing activity of the Co@S–rGO composite can be attributed to the special synergism between the Co and S–rGO components and the extended electrochemically active surface area of Co nanodeposits in this noble metal free electrocatalyst. [ABSTRACT FROM AUTHOR]

Here, we present fabrication of Graphene oxide (GO) supported Cu/Cu x O nano-electrodeposits which can efficiently and selectively electroreduce CO 2 into ethylene with a faradaic efficiency (F.E) of 34% and a conversion rate of 194 mmol g -1 h -1 at -0.985 V vs. RHE. The effect of catalyst morphology, working electrode fabricational techniques, the extent of metal-GO interaction and the oxide content in Cu/Cu x O, was studied in detail so as to develop a protocol for the fabrication of an active, stable and selective catalyst for efficient electro-production of ethylene from CO 2 . Moreover, a detailed comparative study about the effect of the GO support, and the nature of the cathodic collection substrate used for the electro-deposition is presented., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)