Different types of newly synthetized eco-friendly, low-cost carbon quantum dots (CDs) are evaluated to achieve carbon-based laser devices utilizing planar micro-cavities. The results constitute a step forward towards developing alternative eco-friendly carbon-based light-emitting devices aimed to replace current ones based on costly rare-earth and toxic metal elements.

Wavelength-selective light absorbers, emitters, or spectroscopic energy transducers for light, are widely utilized in our society by providing wide variety of applications in lighting, solar energy harvesting, remote sensing, and label free bio-sensing. With the combination of novel and efficient phosphor materials and simple micro- and nano-architectures, such as Fabri-Perot resonator1,2 and whispering gallery resonatores3, and polaritonic grating absorbers4, one can engineer spectroscopic feature in wavelength conversion and light amplification which will be useful for lighting application and photonic encryption. Fluorescent carbon dots/carbonized polymer dots (CDs/ CPDs) are promising materials that exhibit unique luminescence in the visible-to near-infrared wavelength region. These metal-free novel phosphor materials have gained significant interest because of their unique optical properties, photo stability, low cost, and low toxicity, thus being utilized in widespread applications in various fields, including optoelectronic devices. Owing to the limitations of rare-earth elements and heavy toxic effects of chalcogenides and perovskite quantum dots on the environment and biological systems, researchers have started focusing on CDs/CPDs to overcome the drawbacks of conventional phosphor materials. In this talk, we introduce some of our recently developed light-emitting devices combining metal-free carbogenic phosphors and DBR based microcavity as well as microbeads for controlling the sharp resonant emission and chromaticity via wavelength-selective photoluminescence as well as lasing and infrared emission. By adopting Fabri-Perot structure with two dielectric multilayer-photonic mirrors, we could realize light amplification in the blue wavelength region. We could also observe whispering gallery mode from the CPDs in the visible to the red and finally in the near infrared region. These proposed devices in this study will open a new avenue for potential applications in chromaticitytunable white light emitters, lasers5, spectroscopic authentication, and single-microparticle-based chemical/bio sensing.

Carbonized polymer dots (CPDs) are versatile nanomaterials with remarkable optical properties that enable their use in a wide range of photonics applications. CPDs exhibit excitation-wavelength-dependent tunable emissions that span the visible to near-infrared (NIR) spectrum. In this study, whispering-gallery-mode (WGM) emission achieved using CPDs-coated monodisperse polystyrene (PS) microbeads (CPDs@PS) are used to develop wavelength-adaptable photonic barcodes by leveraging the excitation-dependent photoluminescence of CPDs. Each resonant emission peak acts as a unique fingerprint of photonics barcodes related to the corresponding microresonator caused by WGM emission. These photonic barcodes can be easily disguised and then authenticated by varying the excitation wavelength. WGM-based barcodes can exhibit a large number of encoding capacities by adjusting the resonator diameter. Monodisperse CPDs@PS microbeads (3, 4.5, and 6 µm) are used to demonstrate adaptable photonic barcodes, which can improve the readability and reproducibility of spectral patterns for the reliable tagging and identification of commodities. Unlike traditional semiconductor quantum dots or dye-doped microresonators, this adaptive resonant emission does not require structural or chemical modifications, making it an ideal candidate for multiplexed assays, cell tagging and tracking, anti-counterfeiting, and for ensuring the integrity and authenticity of products in various high-value sectors.

Metal-free, luminescent, carbogenic nanomaterials (LCNMs) constitute a novel class of optical materials with low environmental impact. LCNMs, e.g., carbon dots (CDs), graphitic carbon nitride (g-C3N4), and carbonized polymer microspheres (CPM) show strong blue/cyan emissions, but rather weak yellow/red emission. This has been a serious drawback in applying them to light-emitting and bio-imaging applications. Here, by integrating single-component LCNMs in photonic microcavities, the study spectroscopically engineers the coupling between photonic modes in these microcavities and optical transitions to “reconfigure” the emission spectra of these luminescent materials. Resonant photons are confined in the microcavity, which allows selective re-excitation of phosphors to effectively emit down-converted photons. The down-converted photons re-excite the phosphors and are multiply recycled, leading to enhanced yellow/red emissions and resulting in white-light emission (WLE). Furthermore, by adjusting photonic stop bands of microcavity components, color adaptable (cool, pure, and warm) WLE is flexibly generated, which precisely follows the black-body Planckian locus in the chromaticity diagram. The proposed approach offers practical low-cost chromaticity-adjustable WLE from single-component, luminescent materials without any chemical or surface modification, or elaborate machinery and processing, paving the way for practical WLE devices.

Colloidal carbon dots (CDs) have garnered much attention as metal-free photoluminescent nanomaterials, yet creation of solid-state fluorescent (SSF) materials emitting in the deep red (DR) to near-infrared (NIR) range poses a significant challenge with practical implications. To address this challenge and to engineer photonic functionalities, a micro-resonator architecture is developed using carbonized polymer microspheres (CPMs), evolved from conventional colloidal nanodots. Gram-scale production of CPMs utilizes controlled microscopic phase separation facilitated by natural peptide cross-linking during hydrothermal processing. The resulting microstructure effectively suppresses aggregation-induced quenching (AIQ), enabling strong solid-state light emission. Both experimental and theoretical analysis support a role for extended π-conjugated polycyclic aromatic hydrocarbons (PAHs) trapped within these microstructures, which exhibit a progressive red shift in light absorption/emission toward the NIR range. Moreover, the highly spherical shape of CPMs endows them with innate photonic functionalities in combination with their intrinsic CD-based attributes. Harnessing their excitation wavelength-dependent photoluminescent (PL) property, a single CPM exhibits whispering-gallery modes (WGMs) that are emission-tunable from the DR to the NIR. This type of newly developed microresonator can serve as, for example, unclonable anti-counterfeiting labels. This innovative cross-cutting approach, combining photonics and chemistry, offers robust, bottom-up, built-in photonic functionality with diverse NIR applications.

Light-element-based fluorescent materials, colloidal graphene quantum dots, and carbon dots (CDs) have sparked an immense amount of scientific interest in the past decade. However, a significant challenge in practical applications has emerged concerning the development of solid-state fluorescence (SSF) materials. This study addresses this knowledge gap by exploring the unexplored photonic facets of C-based solid-state microphotonic emitters. The proposed synthesis approach focuses on carbonized polymer microspheres (CPMs) instead of conventional nanodots. These microspheres exhibit remarkable SSF spanning the entire visible spectrum from blue to red. The highly spherical shape of CPMs imparts built-in photonic properties in addition to its intrinsic CD-based attributes. Leveraging their excitation-dependent photoluminescence property, these microspheres exhibit amplified spontaneous emission, assisted by the whispering gallery mode resonance across the visible spectral region. Remarkably, unlike conventional semiconductor quantum dots or dye-doped microresonators, this single microstructure showcases adaptable resonant emission without structural/chemical modifications. This distinctive attribute enables a plethora of applications, including microcavity-assisted energy transfer for white light emission, highly sensitive chemical sensing, and secure encrypted anticounterfeiting measures. This interdisciplinary approach, integrating photonics and chemistry, provides a robust solution for light-element-based SSF with inherent photonic functionality and wide-ranging applications.

The proliferation of green technologies to combat the energy crisis has fostered the demand for efficient electrocatalysts towards the hydrogen evolution reaction (HER). It is a challenge to realize electrocatalysts with high activity and stability. Herein, we report a combinatorial design strategy by coupling Ru and CrN to boost the HER performance and durability, surpassing pristine Ru/NC, CrN/NC, and even commercial Pt/C. An in situ Ru-CrN decoration over N-doped carbon (Ru-CrN/NC) is achieved via one-step pyrolysis. CrN induces an electronic modulation in the hybrid that allows facile electron transfer to improve the HER activity. A drastic drop in the η10 for Ru-CrN/NC to 7 and 2 times relative to CrN/NC and Ru/NC, respectively, is observed in alkaline media. Similar observations have been made in acidic media as well. Ru-CrN/NC shows high durability in both the reaction media after 24 h of operation, outperforming commercial Pt/C along with superior mass activity. The activity is mainly controlled by Ru and enhanced further due to the coupling with CrN, and the stability is due to the presence of CrN that inhibits the agglomeration of Ru. Density functional theory (DFT) calculations are done to explore the role of Ru and CrN components in the heterostructure, active sites for intermediate adsorption, revealing that the electronic modulation in the Ru-CrN system enhances the HER compared to Ru/NC.

Polymeric carbon dots (PCDs) are an astonishing class of fluorescent materials with distinctive structures, properties, and applications. However, the internal structures of PCDs are still unclear and are the subject of considerable debate due to their complexity. Herein, a new type of pure blue light-emitting PCDs was synthesized hydrothermally from ϵ-poly-l-lysine and citric acid. PCDs were observed by using scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS) on an atomically thin graphene surface to determine the internal structure and compositional gradients combined with other spectroscopic analyses. These methods revealed that PCDs have a spongy, porous structure with uniform element distribution, reflecting organic polymeric frameworks that embrace fluorescent aromatic moieties devoid of graphitic, inorganic carbon. The polymeric framework acts as a transparent matrix and effectively resists self-quenching of photoluminescence (PL) in the solid state. Exploiting their excellent fluorescence properties, PCDs were embedded in a planar microcavity composed of two distributed Bragg reflectors (DBR), which was demonstrated as a single longitudinal solid-state blue laser. The results will facilitate a detailed understanding of internal structures of PCDs and their efficient, solid-state emission toward the development of rare-earth-free lighting devices.

Multicolor emissions from carbon dots (CDs) are vital for light-emitting diodes (LEDs), particularly for direct, white-light emission (WLE), which enables a replacement of rare earth (RE)-doped phosphors. However, the difficulty of synthesizing single-component WLE CDs with full-spectrum emission severely hinders further investigation of their emission mechanisms and practical applications. Here, we demonstrate rational design and synthesis of chromatically tunable CDs with cyan-, orange-, and white-light emission, precisely tunable along the blackbody Planckian locus by controlling the ratio of different nitrogen dopant sites. We adopted 15N solid-state nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) to identify and quantify N-dopants in different sites and environments, and we explain their influence on emission properties of these CDs. This study provides guiding principles to achieve spectrally tuned emissions, enabling us to design WLE from CDs. This study also clarifies which chemical reagents and their proportions should be used for solvothermal synthesis to realize well-defined WLE from single-component CDs and adjustable, correlated color temperature (CCT) from 6500 to 3500 K. We also demonstrate a soft lighting device by adopting an optical haze film composed of cellulose fibers with excellent light-tailoring characteristics. The proposed methodology for synthesizing WLE CDs by engineering the N-doping sites will boost the development of lighting devices with readily available materials toward realization of low-cost, environmentally friendly WLEDs, solar cells, UV-blockers, counterfeit inks, and display applications.

The solid-state hard encapsulation of carbon dots (CDs) can introduce an additional dimension for the tuning of their optical properties and effective promotion of multifunctional applications as well. In this study, simple hydrothermal and soft-sintering processes have been demonstrated to obtain silicon oxynitride-encapsulated N-doped carbon dots (SiON@NCDs) as well as organosilane-functionalized NCDs (OSi-NCDs). The surface-decorating long alkyl chains on NCDs help to prevent luminescence quenching in solid state and emit blue to orange color while forming a smooth film coating on the substrate. Interestingly, these OSi-NCDs can be readily converted into SiON-encapsulated NCDs (SiON@NCDs) and form a smooth, hard, and visible light transparent coating on a glass surface after soft sintering. This hard coating has the ability to emit white light and 100% block all types of toxic UV light (UV-A, B, and C). The process reported here provides a unique strategy to modulate the NCD luminance properties from blue to white light emission (WLE) by transforming the organosilane matrix together with the NCDs themselves, possibly modified at their surface defects or functional groups. The transformation process involves the conversion of organosilane into a SiON hard-coat matrix via the reaction with the amine surface groups on NCDs. Subsequently, the hard-coat-embedded NCD films emit WLE under UV excitation with good color stability and adjustable correlated color temperature (CCT) from warm white to cool white (3900-7300 K) depending upon their thicknesses. The process proposed here can be adopted for glass hard coating for white light emission (WLE) and UV-light blocking applications. Also, with our proposed hard encapsulation scheme, NCDs are endowed with long-term stability in harsh environmental conditions, which enables these materials for practical applications in many fields, including automotive, illumination industrial sectors, and luminescent solar cells (solar cell windows).

Our eyes and skin are routinely exposed to hazardous ultraviolet light (UV) from sunlight as well as to high-energy blue light (HEBL) from modern IT devices. Therefore, it is essential to protect our health by blocking this harmful high-energy radiation. In this study, we demonstrated a biodegradable, transparent, flexible film that blocks this dangerous radiation using cellulose-encapsulated, nitrogen-doped, carbon dots (NCDs). The interaction between cellulose and NCDs by H-bonding enables effective incorporation of NCDs into the cellulose matrix (NCDs@cel). This film blocks UV-A and UV-B as well as HEBL. Absorbed UV and HEBL are converted into lower-energy (longer-wavelength) light in the blue to green region, reflecting its excitation-dependent emission properties. Hence, the film protects us from exposure to harmful photoradiation. The film’s excellent visible transparency at 540 nm, strong UV blocking, and downconverted emission wavelengths can readily be tuned by simply adjusting the concentration of NCDs in the cellulose film. This hybrid film offers promising solutions to efficiently block UV and HEBL light simultaneously, potentially enabling practical applications such as window coatings against sunlight or for display screens.

With synergy of structural stability and availability of plenty of active sites with open structure for better reactant/product accessibility, dendritic nanostructures stand alone. However, the complexities/difficulties in their design have largely hindered their wide-scale adoption in catalysis. Herein, with this work we report a green and new protocol for the synthesis of unsupported as well as reduced graphene oxide (rGO)-reinforced dendritic Ru nanostructures (Ru@rGO) via controlled galvanic replacement reaction with Mg as the sacrificial metal. Interestingly, experimental findings elucidate Ru@rGO as a promising electrocatalyst for hydrogen evolution reaction (HER) in a wide range of pH with nearly zero onset potential and superior current density as compared with the state-of-art Pt/C catalyst in alkaline as well as acidic media. It requires only 32 and 68 mV overpotential (η) to achieve a current density of 10 mA cm-2 in 1 M KOH and 1 M H2SO4 solution, respectively. Poisoning test conducted in the presence of thiocyanate (SCN-) elucidates the direct involvement of Ru nanostructures. Overall, the unique morphology and the interaction between Ru dendrites with rGO lead to the high HER activity. In addition to electrocatalytic superiority, Ru@rGO is found to be an effective catalyst for the reduction of 4-nitrophenol (an industrial waste) to 4-aminophenol (a value-added product) indicating its bi-functionality as well as adaptive nature for different catalytic environments. This green synthesis protocol driven by the respective redox energy level positioning of Mg, rGO and Ru, as revealed by ultraviolet photoelectron spectroscopic studies, opens up the potential to develop various mono-/bi-metallic nanodendrites for renewable energy harvesting and neutralizing the toxic chemicals in wastewater for environmental remediation.

We report the synthesis of a transparent plastic material with very high performance ultraviolet (UV)-blocking and blue-light (440 nm) emission. Polyvinyl alcohol (PVA) was employed as a transparent plastic matrix that disperses N-doped carbon dots (N-CDs) prepared via hydrothermal treatment of citric acid, ethylene diamine, and HCl solution. Luminescence of these N-CDs is excitation-independent and the quantum yield (QY) is maximal at an excitation wavelength range of 350–370 nm, in the UV-A radiation segment of the solar spectrum. By encapsulating N-CDs in a polyvinyl alcohol (PVA) matrix, the absolute QY achieves 91%, which is higher than in aqueous solution. As the particle concentration increases in PVA matrix or in solution, UV absorbance increases and QY decreases. On the other hand, UV absorbance of the film is proportional to thickness with no appreciable deterioration in QY, a quality that is beneficial for UV light absorption as well as conversion into blue light. We propose that this N-CD/PVA composite is an ideal transparent plastic for UV-ray shielding, as well as being useful for blue light emission, composed only of eco-friendly nontoxic elements. The high UV absorption and strong luminescence of N-CDs are beneficial also for other applications that include anti-counterfeiting (secret inks) and greenhouse sheathing that simultaneously blocks UV-rays while generating blue light to promote plant growth.

Development of significantly active and stable bifunctional catalysts toward hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) remains a challenge. It is also challenging to find a suitable support for the catalysts. Though the N-doped graphene tube (NGT) has many advantages over others due to its excellent electrical conductivity, high surface area, easy synthesis, and low cost, it shows very poor HER and ORR activity. Here, we report the in situ decoration of Ru nanocrystals (Ru NCs) on NGT (Ru@NGT) and their applications as efficient bifunctional electrocatalyst toward ORR and HER. The coordinated Ru complex (ruthenium acetylacetonate) is a unique precursor which directly converted to ultrafine (∼2 nm) and highly dispersed Ru NCs on NGT surface at low temperature without any treatment of the NGT surface. Because of strong coupling with the Ru on NGT, the hydrogen evolution activity drastically enhances. It shows zero onset potential and better current density as compared to 20% Pt/C catalyst in alkaline medium with long-term stability. The overpotential required to achieve a current density of 10 mA/cm2 is 75 mV for Pt/C, whereas it requires only 45 mV for the three-dimensional electrode of Ru@NGT/Ni foam. Similarly, the Ru@NGT also shows excellent ORR performance with a limiting current density of 5.0 mA/cm2 with long-term stability and alcohol tolerance activity. This high activity and better performance is due to the electron transfer from Ru NCs to NGT and better electron transfer within the NGT.

The synthesis is described of a pH-universal hydrogen evolution electrocatalyst based on N and P co-doped graphitic carbon encapsulated OsP2 (OsP2@NPC) nanoparticles of 1.8 nm size for the electrocatalytic hydrogen evolution reaction (HER). Our OsP2-based catalyst is catalytically active at all pH values and delivers the benchmark current density of 10 mA cm-2 at an overpotential of 46, 90 and 144 mV in acidic, alkaline and neutral pH, respectively.

Here, Pd-coated Ru nanocrystals supported on N-doped graphene (Pd-Ru@NG) are obtained via electroless deposition of Pd on Ru nanocrystals. We have demonstrated that Pd boosts the electrocatalytic performance of Pd-Ru@NG towards the hydrogen evolution reaction (HER) and alcohol tolerant oxygen reduction reaction (ORR) as compared to Pt/C.

Pt is known to be a state-of-the-art catalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), while it can also be used for the hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The quest is ongoing to find a suitable catalyst to circumvent the problems associated with the precious metal Pt. Here, we report a facile and green strategy to fabricate CoFe nanoalloys encapsulated in N-doped graphene layers (CoxFe1-x@N-G) by pyrolysis and their catalytic activity toward ORR, HER, and hydrogenation of 4-NP. Intensive studies have been carried out to elucidate the roles of alloying and N-doping. The catalytic activity is found to improve with increasing amounts of Co in the CoFe core and N-doping in the graphene layers. A similar onset potential with better current density as compared to the state-of-the-art Pt/C catalyst in alkaline medium has been achieved for CoxFe1-x@N-G toward ORR activity. These catalysts also show efficient and highly stable HER activity and are very efficient and magnetically separable in the hydrogenation of 4-NP to 4-AP. Overall, the non-precious-metal alloy nanostructures can be exploited as multifunctional catalysts in fuel cells, hydrogen storage systems, and wastewater treatment.

Developing an efficient and cost-effective electrocatalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is of paramount importance for designing metal-air batteries and water electrolyzers. Herein, we present an economical approach for the synthesis of a bifunctional electrocatalyst consisting of cobalt-chromium nanostructures entrapped in a graphene tube doped with nitrogen (CoCr@NGT). The graphene tube is of a large size (cross-sectional diameter ∼ 100 nm) with a wall thickness of more than 10 graphene layers. The Cr alloying with the entrapped Co in the NGT drastically enhanced both the HER and OER performance with a low overpotential (η) and better current density along with long-term durability. Hence, CoCr@NGT can be used as a total alkaline water electrolyzer as both an anode and cathode catalyst delivering a current density of 10 mA/cm2 at around 1.58 V for a long period of time competing with the state-of-the-art combination of Pt-C and RuO2. The electrochemical performance strongly depends on the Cr due to its corrosion resistance capability and improved catalytic sites, which leads to long-term stability and very high activity, respectively.

When solid graphene oxide (GO) is treated with microwave, it generates a huge amount of heat followed by reduction and exfoliation. This can be used as a high temperature reactor for ultrafast and in situ synthesis of reduced graphene oxide (rGO) based hybrids within 60 s in an open atmosphere. rGO based hybrids such as Fe3C-G@rGO, Co-Fe3C-G@rGO, Fe-Fe3C-NG@rGO, CoO@rGO, and Pt@rGO (G represents graphene, and NG represents N-doped graphene) have been synthesized by simply mixing appropriate precursors with GO and treating with microwave. The experiments require neither any external high temperature reactors/furnaces nor any chemical reagents or solvents. Then, rGO based hybrids have been exploited for oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and methanol oxidation activity. CoO@rGO and Co-Fe3C-G@rGO show outstanding OER performances with very low overpotential (η) and a current density of 10 mA/cm2 at 1.52 and 1.56 V with long-term stability. Fe-Fe3C-NG@rGO hybrid shows better oxygen reduction performances, and the onset potential is comparable with precious Pt/C catalyst. The Pt@rGO is highly stable toward methanol oxidation as compared to the Pt/C catalyst. The high catalytic activity and stability are believed to be due to the better adherence of different inorganic nanostructures onto rGO. We strongly believe that this methodology would pave the way for a new era of synthesis of rGO based various hybrids for various applications.

Since hydrogen is a clean and renewable energy source, the design of efficient and new catalysts for hydrogen evolution reaction (HER) has attracted significant attention. Ultrafine (∼2 nm) monodispersed Ru nanocrystals on N-doped graphene (Ru@NG) show Pt-like catalytic activity towards HER in both alkaline and acidic media with zero onset potential and better current density as compared to Pt/C. The HER performance strongly depends on the nanosize effect of Ru nanocrystals and their dispersion on NG. Transfer of electrons from Ru to carbon results in an electron-deficient metal centre and greatly enhances the HER activity. This new 4-d transition metal electrocatalyst has the potential to serve as an alternative to the Pt benchmark catalyst, which is more costly than Ru.

Here, we demonstrate a green and environment-friendly pyrolysis route for the synthesis of metal-rich sulphide embedded in an N-doped carbon (NC) framework in the absence of sulphide ions (S2-). The metal-chelate complex (tris(ethylenediamine) metal(ii) sulfate) serves as a new and single source precursor for the synthesis of earth abundant and non-precious hybrid structures such as metal-rich sulphides Co9S8@NC and Ni3S2@NC when MII = Co2+ and Ni2+ and counter sulphate (SO42-) ions are the source of S. Both the hybrids show superior OER activity as compared to commercial RuO2.

We report a unique, single source precursor Prussian blue (iron(iii) ferrocyanide (FeIII4[FeII(CN)6]3)) for the synthesis of Fe/Fe3C nanoparticle encapsulated N-doped graphitic layers and bamboo-like graphitic nanotubes. Hollow N-doped graphite (N-HG) nanostructures are obtained when the encapsulated nanostructures are treated with an acid. Both the encapsulated nanostructures and N-HG are shown to be applicable as bi-functional electrocatalysts for oxygen reduction (ORR) and oxygen evolution reactions (OER). The ORR activity is shown to be improved for N-HG and is comparable to commercial Pt/C. On the other hand, encapsulated nanostructures exhibit OER activity with long-term stability comparable to commercial RuO2.

Here, we demonstrate a Si-mediated environmentally friendly reduction of graphene oxide (GO) and the fabrication of its hybrids with multiwall carbon nanotubes and nanofibers. The reduction of GO is facilitated by nascent hydrogen generated by the reaction between Si and KOH at ∼60°C. The overall process takes 5 to 7 minutes and 10 to 15 μm of Si is consumed each time. We show that Si can be used multiple times and the rGO based hybrids can be used for electrode materials.

We report a one-pot hydrothermal synthesis of nitrogen doped reduced graphene oxide (N-rGO) and Ag nanoparticle decorated N-rGO hybrid nanostructures from graphene oxide (GO), metal ions and hexamethylenetetramine (HMT). HMT not only reduces GO and metal ions simultaneously but also acts as the source for the nitrogen (N) dopant. We show that the N-rGO can be used as a metal-free surface enhanced Raman spectroscopy (SERS) substrate, while the Ag nanoparticles decorated N-rGO can be used as an effective SERS substrate as well as a template for decorating various other nanostructures on N-rGO. This journal is

We report a new protocol for the synthesis of M@rGO (M = Au, Pt, Pd, Ag and rGO = reduced graphene oxide) hybrid nanostructures at room temperature in Zn-acid medium. The roles of Zn-acid are to reduce the GO by generated hydrogen and the deposition of metal nanoparticles on rGO by galvanic replacement reaction between Zn and Mn+. © 2013 The Royal Society of Chemistry.

We report an environment friendly and green approach to obtain few-layer graphene by the almost instantaneous reduction of graphene oxide using Mg ribbons in acidic solution with a hydrogen spillover mechanism. The typical time is 1-5 min, which is much faster than the reduction by other metal catalysts. © The Royal Society of Chemistry 2013.

We report the room temperature cell performance of alkaline direct methanol fuel cells (ADMFCs) with nitrogen-doped carbon nanotubes (NCNTs) as cathode materials. NCNTs show excellent oxygen reduction reaction activity and methanol tolerance in alkaline medium. The open-circuit-voltage (OCV) as well as the power density of ADMFCs first increases and then saturates with NCNT loading. Similarly, the OCV initially increases and reaches saturation with the increase in the concentration of methanol feed stock. Overall, NCNTs exhibit excellent catalytic activity and stability with respect to Pt based cathodes. © 2013 The Royal Society of Chemistry.