Abdulrahman O. Al-Youbi

Hydrothermal Treatment of Grass: A Low‐Cost, Green Route to Nitrogen‐Doped, Carbon‐Rich, Photoluminescent Polymer Nanodots as an Effective Fluorescent Sensing Platform for Label‐Free Detection of Cu(II) Ions

Increasing reaction temperature produces photoluminescent polymer nanodots (PPNDs) with decreased particle size and increased quantum yield. Such PPNDs are used as an effective fluorescent sensing platform for label-free sensitive and selective detection of Cu(II) ions with a detection limit as low as 1 nM. This method is successfully applied to determine Cu(2+) in real water samples.

Economical, Green Synthesis of Fluorescent Carbon Nanoparticles and Their Use as Probes for Sensitive and Selective Detection of Mercury(II) Ions

The present article reports on a simple, economical, and green preparative strategy toward water-soluble, fluorescent carbon nanoparticles (CPs) with a quantum yield of approximately 6.9% by hydrothermal process using low cost wastes of pomelo peel as a carbon source for the first time. We further explore the use of such CPs as probes for a fluorescent Hg(2+) detection application, which is based on Hg(2+)-induced fluorescence quenching of CPs. This sensing system exhibits excellent sensitivity and selectivity toward Hg(2+), and a detection limit as low as 0.23 nM is achieved. The practical use of this system for Hg(2+) determination in lake water samples is also demonstrated successfully.

Ultrathin Graphitic Carbon Nitride Nanosheet: A Highly Efficient Fluorosensor for Rapid, Ultrasensitive Detection of Cu2+

A highly efficient fluorosensor based on ultrathin graphitic carbon nitride (g-C₃N₄) nanosheets for Cu(2+) was developed. In the absence of metal ions, the nanosheets exhibit high fluorescence; the strong coordination of the Lewis basic sites on them to metal ions, however, causes fluorescence quenching via photoinduced electron transfer leading to the qualitative and semiquantitative detection of metal ions. This fluorosensor exhibits high selectivity toward Cu(2+). The whole detection process can be completed within 10 min with a detection limit as low as 0.5 nM. The use of test paper enables the naked-eye detection of Cu(2+) with a detection limit of 0.1 nmol. The practical use of this sensor for Cu(2+) determination in real water samples was also demonstrated.

Au-Nanoparticle-Loaded Graphitic Carbon Nitride Nanosheets: Green Photocatalytic Synthesis and Application toward the Degradation of Organic Pollutants

Au nanoparticles (AuNPs) were loaded on graphitic carbon nitride (g-C3N4) nanosheets prepared by ultrasonication-assisted liquid exfoliation of bulk g-C3N4 via green photoreduction of Au(III) under visible light irradiation using g-C3N4 as an effective photocatalyst. The nanohybrids show superior photocatalytic activities for the decomposition of methyl orange under visible-light irradiation to bulk g-C3N4, g-C3N4 nanosheets, and AuNP/bulk g-C3N4 hybrids.

Biomolecule-Assisted, Environmentally Friendly, One-Pot Synthesis of CuS/Reduced Graphene Oxide Nanocomposites with Enhanced Photocatalytic Performance

In this work, we develop a novel environmentally friendly strategy toward one-pot synthesis of CuS nanoparticle-decorated reduced graphene oxide (CuS/rGO) nanocomposites with the use of L-cysteine, an amino acid, as a reducing agent, sulfur donor, and linker to anchor CuS nanoparticles onto the surface of rGO sheets. Upon visible light illumination (λ > 400 nm), the CuS/rGO nanocomposites show pronounced enhanced photocurrent response and improved photocatalytic activity in the degradation of methylene blue (MB) compared to pure CuS. This could be attributed to the efficient charge transport of rGO sheets and hence reduced recombination rate of excited carriers.

Ultrathin graphitic carbon nitride nanosheets: a novel peroxidase mimetic, Fe doping-mediated catalytic performance enhancement and application to rapid, highly sensitive optical detection of glucose.

In this article, we demonstrate for the first time that ultrathin graphitic carbon nitride nanosheets (g-C3N4) possess peroxidase activity. Fe doping of the nanosheets leads to peroxidase mimetics with greatly enhanced catalytic performance and the mechanism involved is proposed. We further demonstrate the novel use of such Fe-g-C3N4 as a cheap nanosensor for simple, rapid, highly selective and sensitive optical detection of glucose with a pretty low detection limit of 0.5 μM.

Three-Dimensional Porous Supramolecular Architecture from Ultrathin g-C3N4 Nanosheets and Reduced Graphene Oxide: Solution Self-Assembly Construction and Application as a Highly Efficient Metal-Free Electrocatalyst for Oxygen Reduction Reaction

Direct mixing of aqueous dispersions of ultrathin g-C3N4 nanosheets and graphene oxide (GO) under ultrasonication leads to three-dimensional (3D) porous supramolecular architecture. Photoreduction of GO yields conductive porous g-C3N4/rGO hybrid. The resulting 3D architecture possesses high surface area, multilevel porous structure, good electrical conductivity, efficient electron transport network, and fast charge transfer kinetics at g-C3N4/rGO interfaces, which facilitate the diffusion of O2, electrolyte, and electrons in the porous frameworks during oxygen reduction reaction (ORR). Ultrathin g-C3N4 nanosheet also causes effective electron tunneling through g-C3N4 barrier, leading to rich electrode-electrolyte-gas three-phase boundaries, and shortens the electron diffusion distance from rGO to O2. As a novel ORR catalyst, such 3D hybrid exhibits remarkable catalytic performance, outperformed other g-C3N4/rGO composites, and exhibits excellent durability.

Environmentally Friendly, One-Pot Synthesis of Ag Nanoparticle-Decorated Reduced Graphene Oxide Composites and Their Application to Photocurrent Generation

In this paper, we develop an environmentally friendly, one-pot strategy toward rapid preparation of Ag nanoparticle-decorated reducd graphene oxide (AgNPs/rGO) composites by heating the mixture of GO and AgNO(3) aqueous solution in the presence of sodium hydroxide at 80 °C under stirring. The reaction was accomplished within a short period of 10 min without extra reducing agent. As-synthesized AgNPs/rGO composites have been successfully applied in photocurrent generation in the visible spectral region.

Spinel CuCo2O4 Nanoparticles Supported on N-Doped Reduced Graphene Oxide: A Highly Active and Stable Hybrid Electrocatalyst for the Oxygen Reduction Reaction

In this Letter, for the first time, we demonstrated the preparation of a highly efficient electrocatalyst, spinel CuCo2O4 nanoparticles supported on N-doped reduced graphene oxide (CuCo2O4/N-rGO), for an oxygen reduction reaction (ORR) under alkaline media. The hybrid exhibits higher ORR catalytic activity than CuCo2O4 or N-rGO alone, the physical mixture of CuCo2O4 nanoparticles and N-rGO, and Co3O4/N-rGO. Moreover, such a hybrid affords superior durability to the commercial Pt/C catalyst.

Ag nanoparticles decorated polyaniline nanofibers: synthesis, characterization, and applications toward catalytic reduction of 4-nitrophenol and electrochemical detection of H2O2 and glucose

Polyaniline nanofibers (PANINFs) have been facilely prepared by electrochemical polymerization of aniline monomers in acidic aqueous media without using any templates and surfactants. The subsequent treatment of such nanofibers with a AgNO3 aqueous solution leads to in situ chemical reduction of Ag+ on them to form Ag nanoparticles decorated PANINFs (AgNPs/PANINFs) nanocomposites. We investigated the catalytic activity and electrochemical properties of these nanocomposites. It is found that such nanocomposites exhibit excellent catalytic activity toward reduction of 4-nitrophenol to 4-aminophenol by NaBH4 and exhibit remarkable catalytic performance for H2O2 reduction. The enzymeless H2O2 sensor constructed using the nanocomposites shows a fast amperometric response time of less than 3 s. The linear range and detection limit are estimated to be from 0.1 mM to 60 mM (r = 0.998) and 1.7 μΜ at a signal-to-noise ratio of 3, respectively. We have fabricated a glucose biosensor by immobilizing glucose oxidase into the AgNPs/PANINFs-modified glassy carbon electrode for glucose detection. This sensor exhibits good response to glucose. The linear response range is estimated to be from 1 mM to 12 mM (r = 0.997) at −0.58 V. The detection limit is estimated to be 0.25 mM at a signal-to-noise ratio of 3.