Metal nitride/graphene nanohybrids: general synthesis and multifunctional titanium nitride/graphene electrocatalyst

Facile access to high-efficiency degradation of tetracycline hydrochloride with structural optimization of TiN

As a broad-spectrum antibiotic, tetracycline has become a potential ecological hazard. Herein, titanium nitride (TiN), with an advantageous structure, was synthesized by simple heating rate regulation and constructed for tetracycline hydrochloride (TC-HCl) degradation under light irradiation. All the samples were characterized by X-ray diffraction (XRD), N2-adsorption/desorption isotherm, ultraviolet-visible diffuse reflectometry (DRS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The results showed that the as-prepared TiN-x catalysts exhibited obviously enhanced photocatalytic property toward TC-HCl degradation compared with the commercial pure phase TiN (p-TiN). According to the results of photocatalytic degradation, TiN synthesized at 6 °C/min heating rate had the best removal rate of TC-HCl (90%) after dark reaction for 10 min and photo-degradation for 90 min. In addition, the trapping experiments have demonstrated that the photogenerated holes (h+) and superoxide radical ([Formula: see text]) are the main oxidation products of the present system. Strikingly, the reuse experiments showed high stability of TiN.

A novel visible light active rare earth doped CdS nanoparticles decorated reduced graphene oxide sheets for the degradation of cationic dye from wastewater

A variety of rare earth metals (La, Sm, Nd, Ce, Gd) doped cadmium sulfide (RE-CdS) grafted reduced graphene oxide (G) sheet nanocomposites estimated imperative attention due to their visible light-driven, tunable band gap and high surface to volume ratio were investigated for the photocatalytic degradation of cationic dye from aqueous solution. The formation of wurtzite (hexagonal) crystal structures of cadmium sulfide nanoparticles (NPs) was confirmed by Powder X-ray diffraction spectra and the average crystallite size was determined to be 10 ± 2 nm. HRTEM analysis confirmed the homogeneous distribution of RE-CdS NPs over the G sheets. The photocatalytic behaviour of the RE-CdS decorated G sheets was studied using a textile dye methylene blue (MB) under sunlight. The result indicates that among the various RE-CdS nanocomposites studied, Cerium-cadmium sulfide-reduced graphene oxide (Ce-CdS-G) shows highest MB degradation of 99.0 ± 0.4% within 90 min under sunlight. The result confirms that RE-CdS-G nanocatalyst efficiently accelerates the separation and slows down the recombination rate in photo excited charge carriers. The catalytic activity was retained over 80% of its original value even after four successive runs and the present method can be employed for the large-scale synthesis of RE-CdS-G nanocatalyst.

Formation of Super-Assembled TiOx /Zn/N-Doped Carbon Inverse Opal Towards Dendrite-Free Zn Anodes

Uncontrolled growth of Zn dendrites and side reactions are the major restrictions for the commercialization of Zn metal anodes. Herein, we develop a TiO_x /Zn/N-doped carbon inverse opal (denoted as TZNC IO) host to regulate the Zn deposition. Amorphous TiO_x and Zn/N-doped carbon can serve as the zincophilic nucleation sites to prevent the parasitic reactions. More importantly, the highly ordered IO host homogenizes the local current density and electric field to stabilize Zn deposition. Furthermore, the three-dimensional open networks could regulate Zn ion flux to enable stable cycling performance at large current densities. Owing to the abundant zincophilic sites and the open structure, granular Zn deposits could be realized. As expected, the TZNC IO host guarantees the steady Zn plating/stripping with a long-term stability over 450 h at the current density of 1 mA cm^-2 . As a proof-of-concept demonstration, a TZNC@Zn||V₂ O₅ full cell shows long lifespan over 2000 cycles at 5.0 A g^-1 .

Solution-processed two-dimensional materials for next-generation photovoltaics

In the ever-increasing energy demand scenario, the development of novel photovoltaic (PV) technologies is considered to be one of the key solutions to fulfil the energy request. In this context, graphene and related two-dimensional (2D) materials (GRMs), including nonlayered 2D materials and 2D perovskites, as well as their hybrid systems, are emerging as promising candidates to drive innovation in PV technologies. The mechanical, thermal, and optoelectronic properties of GRMs can be exploited in different active components of solar cells to design next-generation devices. These components include front (transparent) and back conductive electrodes, charge transporting layers, and interconnecting/recombination layers, as well as photoactive layers. The production and processing of GRMs in the liquid phase, coupled with the ability to "on-demand" tune their optoelectronic properties exploiting wet-chemical functionalization, enable their effective integration in advanced PV devices through scalable, reliable, and inexpensive printing/coating processes. Herein, we review the progresses in the use of solution-processed 2D materials in organic solar cells, dye-sensitized solar cells, perovskite solar cells, quantum dot solar cells, and organic-inorganic hybrid solar cells, as well as in tandem systems. We first provide a brief introduction on the properties of 2D materials and their production methods by solution-processing routes. Then, we discuss the functionality of 2D materials for electrodes, photoactive layer components/additives, charge transporting layers, and interconnecting layers through figures of merit, which allow the performance of solar cells to be determined and compared with the state-of-the-art values. We finally outline the roadmap for the further exploitation of solution-processed 2D materials to boost the performance of PV devices.

Enzyme-Loaded Nanoreactors Enable the Continuous Regeneration of Nicotinamide Adenine Dinucleotide in Artificial Metabolisms

Nicotinamide adenine dinucleotide (NAD) is an essential coenzyme for numerous biocatalytic pathways. While in nature, NAD+ is continuously regenerated from NADH by enzymes, all synthetic NAD+ regeneration strategies require a continuous supply of expensive reagents and generate byproducts, making these strategies unattractive. In contrast, we present an artificial enzyme combination that produces NAD+ from oxygen and water continuously; no additional organic substrates are required once a minimal amount pyruvate is supplied. Three enzymes, i.e., LDH, LOX, and CAT, are covalently encapsulated into a substrate-permeable silica nanoreactor by a mild fluoride-catalyzed sol-gel process. The enzymes retain their activity inside of the nanoreactors and are protected against proteolysis and heat. We successfully used NAD+ from the nanoreactors for the continuous production of NAD+ i) to sense glucose in artificial glucose metabolism, and ii) to reduce the non-oxygen binding methemoglobin to oxygen-binding hemoglobin. This latter conversion might be used for the treatment of Methemoglobinemia. We believe that this versatile tool will allow the design of artificial NAD+ -dependent metabolisms or NAD+ -mediated redox-reactions.

Recent progress of graphene based nanomaterials in bioelectrochemical systems

The application of graphene (Gr) to microbial fuel cells (MFCs) and microbial electrolysis cell (MECs) is considered a very promising approach in terms of enhancing their performance. The superior Gr properties of high electrical and thermal conductivities, along with: superior specific surface area, high electron mobility, and mechanical strength, are the key features that endorse this. Factors impeding the advancement of a microbial fuel cell into commercialization involve primarily the cost of their components, and their production on a small scale. Gr with such outstanding characteristics can help mitigate these challenges, when used as electrode material. The application of Gr as an anode material improves the efficiency of electron transfer and bacterial attachment. When used as a cathode material, it supports the oxygen reduction reaction. This investigation, presents a thorough analysis of the feasibility of Gr as an electrode material in both MFC and MEC applications - based on experimental results from the investigation. Current technological advancements in the implementation of Gr in MFC and MEC are also highlighted in this review. To summarise, the investigation exposes critical issues impeding the advancement of microbial fuel cells, and proposes possible solutions to mitigate these challenges.

Electrodeposited Co-Substituted LaFeO3 for Enhancing the Photoelectrochemical Activity of BiVO4

Co-substituted LaFeO₃ was electrodeposited on the surface of BiVO₄ as a co-catalyst to enhance the water splitting performance. Compared to bare BiVO₄, the BiVO₄/Co-LaFeO₃ composite photoanode shows a water oxidation photocurrent of 3.4 mA/cm² at 1.23 V versus reverse hydrogen electrode, accompanied by a notable cathodic shift in the onset potential for 300 mV. Combined optical and electrochemical characterizations show that the solid/electrolyte charge transfer efficiency of BiVO₄ are dramatically improved by the incorporation of Co-substituted LaFeO₃. From the surface kinetic study of charge carriers by intensity-modulated photocurrent spectroscopy, a suppressed surface recombination rate constant is observed and the enhanced photoelectrochemical water splitting performance observed in the BiVO₄/Co-LaFeO₃ photoanode is attributed to the surface passivation effect of Co-substituted LaFeO₃.

Tunable 3D nanofibrous and bio-functionalised PEDOT network explored as a conducting polymer-based biosensor

Conducting polymers that possess good electrochemical properties, nanostructured morphology and functionality for bioconjugation are essential to realise the concept of all-polymer-based biosensors that do not depend on traditional nanocatalysts such as carbon materials, metal, metal oxides or dyes. In this research, we demonstrated a facile approach for the simultaneous preparation of a bi-functional PEDOT interface with a tunable 3D nanofibrous network and carboxylic acid groups (i.e. Nano-PEDOT-COOH) via controlled co-polymerisation of EDOT and EDOT-COOH monomers, using tetrabutylammonium perchlorate as a soft-template. By tuning the ratio between EDOT and EDOT-COOH monomer, the nanofibrous structure and carboxylic acid functionalisation of Nano-PEDOT-COOH were varied over a fibre diameter range of 15.6 ± 3.7 to 70.0 ± 9.5 nm and a carboxylic acid group density from 0.03 to 0.18 μmol cm^-2. The nanofibres assembled into a three-dimensional network with a high specific surface area, which contributed to low charge transfer resistance and high transduction activity towards the co-enzyme NADH, delivering a wide linear range of 20-960 μM and a high sensitivity of 0.224 μA μM^-1 cm^-2 at the Nano-PEDOT-COOH50% interface. Furthermore, the carboxylic acid groups provide an anchoring site for the stable immobilisation of an NADH-dependent dehydrogenase (i.e. lactate dehydrogenase), via EDC/S-NHS chemistry, for the fabrication of a Bio-Nano-PEDOT-based biosensor for lactate detection which had a response time of less than 10 s over the range of 0.05-1.8 mM. Our developed bio-Nano-PEDOT interface shows future potential for coupling with multi-biorecognition molecules via carboxylic acid groups for the development of a range of advanced all-polymer biosensors.

Reducing the shuttle effect with the interactions of polar TiN and non-polar graphene for lithium–sulfur batteries

Chemical anchoring and facilitated transformation of polysulfides by polar titanium nitride nanoparticles and uniform distribution of sulfur by non-polar graphene showed efficient cooperative interactions for lithium–sulfur batteries.

TiN nanotube supported Ni catalyst Ni@TiN-NTs: experimental evidence of structure–activity relations in catalytically hydrolyzing ammonia borane for hydrogen evolution

With commercial TiO₂ as the precursor, titanium nitride nanotubes (TiN-NTs) were fabricated through a hydrothermal – ammonia nitriding route, and next non-noble metal nanosized Ni particles were evenly and firmly anchored on the surface of the TiN-NTs via a PVP-mediated non-aqueous phase reduction–deposition strategy, to obtain the supported catalyst Ni@TiN-NTs. The X-ray powder diffraction (PXRD), field emission scanning and transmission electron microscopy (FE-SEM/TEM) and specific surface area measurements were used to characterize and analyze the phase composition, surface microstructure and morphological features of the product. The catalytic activity of the Ni@TiN-NTs for hydrolyzing ammonia borane to generate hydrogen (H₂) under different conditions was evaluated systematically. The results reveal that the as-fabricated TiN-NTs are composed of TiN and a small amount of TiN_xO_y with the approximate molar atomic ratio of Ti to N at 1 : 1, existing as hollow microtubules with mean tube diameter of 130 nm and length of about 1 μm. Via in situ reduction and deposition, Ni nanoparticles can be uniformly anchored on the surface of TiN-NTs. The catalytic activities of Ni(x)@TiN-NTs with different Ni loading amounts are all higher than that of single metal Ni nanoparticles. The temperature has a positive effect on the catalytic activity of Ni(20)@TiN-NTs, and its total turnover frequency for hydrolyzing ammonia borane is 11.73 mol(H₂) (mol Ni)⁻¹ min⁻¹, with an apparent activation energy of 52.05 kJ mol⁻¹ at 303 K. After 5 cycles, the Ni(20)@TiN-NTs catalyst still maintains 87% of the initial catalytic activity. It could be suggested that these tactics can also be extended to the fabrication of other metal or alloy catalysts supported by TiN-NTs, with great application potential and development prospects.

Titanium nitride nanotubes (TiN-NTs) were fabricated using a hydrothermal – ammonia nitriding route, and non-noble metal nanosized Ni particles were anchored on the surface via a non-aqueous phase reduction–deposition strategy, to obtain the supported catalyst Ni@TiN-NTs.

Synthesis of Bi4Ti3O12 decussated nanoplates with enhanced piezocatalytic activity

A variety of nanostructured Bi₄Ti₃O₁₂ materials with diverse morphologies were synthesized by a novel hydrothermal method using layered titanate Na₂Ti₃O₇ as a synthetic precursor. Among these materials, decussated nanoplates exhibit superior piezocatalytic activity compared with other piezocatalysts of the perovskite family. The enhanced piezocatalytic activity is attributed to the large piezoelectric potential difference and the short distance between polar surfaces, which may help enhance the driving force of charge transport. The finite element method (FEM) simulation of piezoelectric response in different Bi₄Ti₃O₁₂ nanostructures was performed to illustrate the influence of morphological features on the piezocatalytic performance. The catalytic mechanism of Bi₄Ti₃O₁₂ was investigated by the detection and characterization of free radicals and intermediate products with electron spin resonance (ESR) spin-trapping technique and liquid chromatography-mass spectrometry (LC-MS). This work may push forward the development of piezocatalytic materials, and provide insights into piezocatalysis for environmental applications.

Size, Composition, and Support-Doping Effects on Oxygen Reduction Activity of Platinum-Alloy and on Non-platinum Metal-Decorated-Graphene Nanocatalysts

Recent investigations reported in the open literature concerning the functionalization of graphene as a support material for transition metal nanoparticle catalysts have examined isolated systems for their potential Oxygen Reduction Reaction (ORR) activity. In this work we present results which characterize the ability to use functionalized graphene (via dopants B, N) to upshift and downshift the adsorption energy of mono-atomic oxygen, O* (the ORR activity descriptor on ORR Volcano Plots), for various compositions of 4-atom, 7-atom, and 19-atom sub-nanometer binary alloy/intermetallic transition metal nanoparticle catalysts on graphene (TMNP-MDG). Our results show several important and interesting features: (1) that the combination of geometric and electronic effects makes development of simple linear mixing rules for size/composition difficult; (2) that the transition from 4- to 7- to 19-atom TMNP on MDG has pronounced effects on ORR activity for all compositions; (3) that the use of B and N as dopants to modulate the graphene-TMNP electronic structure interaction can cause shifts in the oxygen adsorption energy of 0.5 eV or more; (4) that it might be possible to make specific doped-graphene-Ni_xCu_y TMNP systems which fall close to the Volcano Peak for ORR. Our results point to systems which should be investigated experimentally and may improve the viability of future fuel cell or other ORR applications, and provide new paths for future investigations of more detail for TMNP-MDG screening.

Surface-Supported Metal-Organic Framework Thin-Film-Derived Transparent CoS1.097@N-Doped Carbon Film as an Efficient Counter Electrode for Bifacial Dye-Sensitized Solar Cells

An effective design for counter electrode (CE) catalytic materials with superior catalytic activity, excellent stability, low cost, and a facile fabrication process is urgently needed for industrialization of dye-sensitized solar cells (DSSCs). Herein, we report a facile in situ method to fabricate transparent CoS_1.097 anchored on an N-doped carbon film electrode through sulfurization of a cobalt-metalloporphyrin metal-organic framework thin film on fluorine-doped tin oxide glass. The transparent film as counter electrode in bifacial DSSCs exhibited higher power conversion efficiency (9.11% and 6.64%), respectively, from front and rear irradiation than that of Pt (8.04% and 5.87%). The uniformly dispersed CoS_1.097 nanoparticles on an N-doped carbon film provide a large catalytic active area and facilitate the electron transfer, which leads to the excellent catalytic ability of the CoS_1.097@N-doped carbon film. In addition, the in situ preparation of the uniform film with a nanosheet structure offers high electrical conductivity and unobstructed access for the diffusion of triiodide to available electroactive sites, resulting in excellent device performance with superior long-term stability over 1000 h under natural conditions.

Recent Progress in the Design and Synthesis of Nitrides for Mesoscopic and Perovskite Solar Cells

With growing concerns about global warming and the energy crisis, a variety of photovoltaic devices have attracted worldwide attention as alternative energy sources. Among them, organic-inorganic hybrid photovoltaics, typically mesoscopic and perovskite solar cells, are promising, owing to their potential for low-cost energy production, which mainly comes from unlimited combinations of materials optimized for each step of solar energy conversion. However, the commercialization of organic-inorganic hybrid solar cells is hampered by costly electrocatalysts or hole-transport materials. Currently, state-of-the-art dye- or quantum-dot-sensitized solar cells and perovskite solar cells necessitate noble metals and high-price polymeric materials. In an attempt to resolve this issue, various kinds of metal compounds have been investigated, and nitrides have been actively reported to possess a number of favorable properties for the aforementioned purpose, such as excellent electrical conductivity and superb electrocatalytic performance. Herein, the use of nitrides as cost-effective electrocatalysts or hole-transport materials in organic-inorganic hybrid solar cells is reviewed. Nitrides with a variety of morphologies and scales are discussed, together with the synergistic effect in the case of diverse composites. In addition, prospects and challenges for applying nitride materials are briefly suggested.

Graphdiyne: Recent Achievements in Photo- and Electrochemical Conversion

As a rising star of carbon allotropes, graphynes (GYs) merely consist of sp- and sp2-hybridized carbon atoms, which endow them a large conjugated network and expanded 2D porous structure. With unique topological structure, GYs display unusual semiconducting properties, especially in the aspects of charge mobility and electron transport. Among the members of the GY family, only graphdiyne (GD) can be successfully synthesized in large quantities. The advanced properties of GD make it promising in various applications. Here, the recent progress in the synthesis of GD and GD-based composites is reviewed as well as their applications in photorelated and electrocatalytic applications. It is hoped that this Review will promote the development and applications of carbon chemistry.

Fe2TiO5 as an Efficient Co-catalyst To Improve the Photoelectrochemical Water Splitting Performance of BiVO4

Fe₂TiO₅ was synthesized via the solvothermal method and adopted as co-catalyst to improve the photoelectrochemical (PEC) water splitting performance of BiVO₄ photoanode. After surface modification by Fe₂TiO₅, the BiVO₄/Fe₂TiO₅ photoanode shows a 300 mV cathodic shift in onset potential and 3 times enhancement in photocurrent, which delivers a photocurrent density of 3.2 mA/cm² at 1.23 V vs reverse hydrogen electrode. Systematic optical, electrochemical, and intensity-modulated photocurrent spectroscopy characterizations were performed to explore the role of Fe₂TiO₅ and reveal that the enhanced PEC performance is mainly caused by the surface passivation effect of Fe₂TiO₅.

Enhanced Pyroelectric Catalysis of BaTiO3 Nanowires for Utilizing Waste Heat in Pollution Treatment

A novel catalytic effect of pyroelectric materials induced by a change in temperature, namely pyroelectric catalysis, was found to be attractive due to its ability to utilize waste heat in pollution treatment. In this work, the pyroelectric catalytic properties of BaTiO₃ (BTO) nanowires synthesized by a template hydrothermal method have been thoroughly investigated. The nanowires with an elongated polar axis show a superior pyroelectric catalytic performance in comparison with the equiaxial nanoparticles. Our numerical simulation results with a finite element method indicate that the enhanced catalytic efficiency of BTO nanowires can be attributed to the higher pyroelectric potential. On the basis of the pyroelectric effect and our experimental results, a pyroelectric catalytic degradation mechanism has been proposed by taking into account the migration of charge carriers and the formation of reaction radicals. This study for enhancing the pyroelectric catalytic activity by using BTO nanowires may provide a facile, promising, and new reusable strategy for the catalytic degradation of organic dye pollutant by means of temperature variation. It is hoped that the present work gives a clear understanding of the mechanism of pyroelectric catalysis.

Mechanochemical-Assisted Synthesis of High-Entropy Metal Nitride via a Soft Urea Strategy

Crystalline high-entropy ceramics (CHC), a new class of solids that contain five or more elemental species, have attracted increasing interest because of their unique structure and potential applications. Up to now, only a couple of CHCs (e.g., high-entropy metal oxides and diborides) have been successfully synthesized. Here, a new strategy for preparing high-entropy metal nitride (HEMN-1) is proposed via a soft urea method assisted by mechanochemical synthesis. The as-prepared HEMN-1 possesses five highly dispersed metal components, including V, Cr, Nb, Mo, Zr, and simultaneously exhibits an interesting cubic crystal structure of metal nitrides. By taking advantage of these unique features, HEMN-1 can function as a promising candidate for supercapacitor applications. A specific capacitance of 78 F g^-1 is achieved at a scan rate of 100 mV s^-1 in 1 m KOH. In addition, such a facile synthetic strategy can be further extended to the fabrication of other types of HEMNs, paving the way for the synthesis of HEMNs with attractive properties for task-specific applications.

Raman spectroscopy of graphene-based materials and its applications in related devices

Graphene-based materials exhibit remarkable electronic, optical, and mechanical properties, which has resulted in both high scientific interest and huge potential for a variety of applications. Furthermore, the family of graphene-based materials is growing because of developments in preparation methods. Raman spectroscopy is a versatile tool to identify and characterize the chemical and physical properties of these materials, both at the laboratory and mass-production scale. This technique is so important that most of the papers published concerning these materials contain at least one Raman spectrum. Thus, here, we systematically review the developments in Raman spectroscopy of graphene-based materials from both fundamental research and practical (i.e., device applications) perspectives. We describe the essential Raman scattering processes of the entire first- and second-order modes in intrinsic graphene. Furthermore, the shear, layer-breathing, G and 2D modes of multilayer graphene with different stacking orders are discussed. Techniques to determine the number of graphene layers, to probe resonance Raman spectra of monolayer and multilayer graphenes and to obtain Raman images of graphene-based materials are also presented. The extensive capabilities of Raman spectroscopy for the investigation of the fundamental properties of graphene under external perturbations are described, which have also been extended to other graphene-based materials, such as graphene quantum dots, carbon dots, graphene oxide, nanoribbons, chemical vapor deposition-grown and SiC epitaxially grown graphene flakes, composites, and graphene-based van der Waals heterostructures. These fundamental properties have been used to probe the states, effects, and mechanisms of graphene materials present in the related heterostructures and devices. We hope that this review will be beneficial in all the aspects of graphene investigations, from basic research to material synthesis and device applications.

Enhanced cyclability of Li-O2 batteries with cathodes of Ir and MnO2 supported on well-defined TiN arrays

The cycling stability of Li-O₂ batteries has been impeded by the lack of high-efficiency, and durable oxygen cathodes for the oxygen-reduction reaction (ORR) and the oxygen-evolution reaction (OER). Herein we report a novel TiN nanorod array-based cathode, which was firstly prepared by growing a TiN nanorod array on carbon paper (CP), and then followed by depositing MnO₂ ultrathin sheets or Ir nanoparticles on the TiN nanorods to form well-ordered, three-dimensional (3D), and free-standing structured cathodes: TiN@MnO₂/CP and TiN@Ir/CP. Both cathodes exhibited good specific capacity and excellent cycling stability. Their specific discharge capacities were up to 2637 and 2530 mA h g^-1, respectively. After 200 cycles for 2000 h at a current density of 100 mA g^-1, no obvious decays were observed for TiN@MnO₂/CP and TiN@Ir/CP cathodes, while significant decreases were observed after the 80^th and 30^th cycles for the Pt/C and TiN/CP cathodes, respectively. Such high performance can be ascribed to the 3D array structure with enough microspace and high surface area, which facilitated the high dispersion of active components and prevented the formation of large/irreversible Li₂O₂.

TiO2/TiN core/shell nanobelts for efficient solar hydrogen generation

TiO₂/TiN core/shell NBs are successfully synthesized, and used as highly efficient photocatalytic H₂ evolution catalysts (120 μmol h⁻¹ g⁻¹) from methanol solution.

Impacts of dissolved organic matter on aqueous behavior of nano/micron-titanium nitride and their induced enzymatic/non-enzymatic antioxidant activities in Scenedesmus obliquus

Freshwater dispersion stability and ecotoxicological effects of titanium nitride (TiN) with particle size of 20 nm, 50 nm, and 2-10 μm in the presence of dissolved organic matter (DOM) at various concentrations were studied. The TiN particles that had a more negative zeta potential and smaller hydrodynamic size showed more stable dispersion in an aqueous medium when DOM was present than when DOM was absent. Biochemical assays indicated that relative to the control, the TiN particles in the presence of DOM alleviated to some extent the antioxidative stress enzyme activity in Scenedesmus obliquus. In addition, it was found that the TiN with a primary size of 50 nm at a high concentration presented a significant impact on non-enzymatic antioxidant defense in algal cells.

Substrate-mediated growth of vanadium carbide with controllable structure as high performance electrocatalysts for dye-sensitized solar cells

VC nanoparticles, from cuboctahedron to cubic, have been synthesized using graphene oxide as the nucleation and growth substrate. The energy conversion efficiency of the DSSCs with the VC-ch counter electrode reached 7.92%, comparable to Pt based CE.

Counter electrodes in dye-sensitized solar cells

This article panoramically reviews the counter electrodes in dye-sensitized solar cells, which is of great significance for the development of photovoltaic and photoelectric devices.

A General Method for Constructing Two-Dimensional Layered Mesoporous Mono- and Binary-Transition-Metal Nitride/Graphene as an Ultra-Efficient Support to Enhance Its Catalytic Activity and Durability for Electrocatalytic Application

We constructed a series of two-dimensional (2D) layered mesoporous mono- and binary-transition-metal nitride/graphene nanocomposites (TMN/G, TM = Ti, Cr, W, Mo, TiCr, TiW, and TiMo) via an efficient and versatile nanocasting strategy for the first time. The 2D layered mesoporous TMN/G is constituted of small TMN nanoparticles composited with graphene nanosheets and has a large surface area with high porosity. Through decoration with well-dispersed Pt nanoparticles, 2D layered mesoporous Pt/TMN/G catalysts can be obtained that display excellent catalytic activity and stability for methanol electro-oxidation reactions (MOR) and oxygen reduction reactions (ORR) in both acidic and alkaline media. The 2D layered mesoporous binary-Pt/TMN/G catalysts possess catalytic activity superior to that of mono-Pt/TMN/G, graphene free Pt/TMN, Pt/G, and Pt/C catalysts. Encouragingly, the 2D layered mesoporous Pt/Ti0.5Cr0.5N/G catalyst exhibits the best electrocatalytic performance for both MOR and ORR. The outstanding electrocatalytic performance of the Pt/Ti0.5Cr0.5N/G catalyst is rooted in its large surface area, high porosity, strong interaction among Pt, Ti0.5Cr0.5N, and graphene, an excellent electron transfer property facilitated by N-doped graphene, and the small size of Pt and Ti0.5Cr0.5N nanocrystals. The outstanding catalytic performance provides the 2D layered mesoporous Pt/Ti0.5Cr0.5N/G catalyst with a wide range of application prospects in direct methanol fuel cells in both acidic and alkaline media. The synthetic method may be available for constructing other 2D layered mesoporous metal nitrides, carbides, and phosphides.

Facile fabrication of FeN nanoparticles/nitrogen-doped graphene core-shell hybrid and its use as a platform for NADH detection in human blood serum

Herein, we present a novel strategy for the synthesis of an iron nitride nanoparticles-encapsulated nitrogen-doped graphene (FeN NPs/NG) core-shell hierarchical nanostructure to boost the electrochemical performance in a highly sensitive, selective, reproducible, and stable sensing platform for nicotinamide adenine dinucleotide (NADH). This core-shell hierarchical nanostructure provides an excellent conductive network for effective charge transfer and avoids the agglomeration and restacking of NG sheets, which provides better access to the electrode material for NADH oxidation. The FeN NPs/NG core-shell hierarchical nanostructure demonstrates direct and mediatorless responses to NADH oxidation at a low potential. This material displays a high sensitivity of 0.028μA/μMcm(2), a wide linear range from 0.4 to 718μM, and a detection limit of 25nM with a fast response time of less than 3s. The interferences from common interferents, such as glucose, uric acid, dopamine, and ascorbic acid, are negligible. The fabricated sensor was further tested for the determination of NADH in human blood serum. The resulting high sensitivity, excellent selectivity, outstanding stability, and good reproducibility make the proposed FeN NPs/NG core-shell hierarchical nanostructure as a promising candidate for biomedical applications.

An integrated nanoplatform for theranostics via multifunctional core-shell ferrite nanocubes

Magnetic core-shell ferrite nanocubes (MNCs) were prepared by a two-step pyrolysis. The MNCs not only exhibit an excellent magnetothermal effect, but also can be used as T₂ magnetic resonance (MR) imaging agents. To obtain their good biocompatibility and targeting ability, MNCs were modified with poly(ethylene glycol) (PEG) and hyaluronic acid (HA). To further construct an integrated nanoplatform for theranostics, doxorubicin (DOX) was loaded onto the surface of MNCs by pH and heat sensitive chemical bonding. Notably, the MNCs showed a great stability and magnetothermal effect. Moreover, they showed negligible toxicity and synergistic therapy in vitro. Meanwhile, their MR imaging in vivo was further verified. A novel integrated nanoplatform facilitates excellent targeted MR imaging guided synergism of magnetothermal and chemotherapy. The multifunctional nanocubes will be capable of playing a vital role in future cancer therapy.

Self-Powered Broadband Photodetector using Plasmonic Titanium Nitride

We report the demonstration of plasmonic titanium nitride (TiN) for fabrication of an efficient hybrid photodetector. A novel synthesis method based on plasma nanotechnology is utilized for producing air stable plasma polymerized aniline-TiN (PPA-TiN) nanocomposite and its integration in photodetector geometry. The device performs as a self-powered detector that responds to ultraviolet and visible light at zero bias. The photodetector has the advantage of broadband absorption and outcomes an enhanced photoresponse including high responsivity and detectivity under low light conditions. This work opens up a new direction for plasmonic TiN-based hybrid nanocomposite and its exploitation in optoelectronic applications including imaging, light-wave communication and wire-free route for artificial vision.

Graphene-supported Pd catalyst for highly selective hydrogenation of resorcinol to 1, 3-cyclohexanedione through giant π-conjugate interactions

The selective hydrogenation of resorcinol (RES) to 1, 3-cyclohexanedione (1,3-CHD) without the addition of alkali is a big challenge. In this article, a novel reduced graphene oxide (rGO) supported Pd catalyst was prepared through co-reduction method, over which we obtained 99.9% of resorcinol conversion and 94.2% of the ever-reported highest 1,3-cyclohexanedione selectivity at 25 °C in only CH₂Cl₂ solvent. The excellent selectivity was contributed to the strong π-π and p-π interactions between the graphene nanosheet and the benzene ring as well as hydroxyl in RES molecule. The followed adsorption experiment and Raman analysis also showed the existence of aromatic graphite structures in rGO, which exhibited stronger adsorption towards RES than towards 1,3-CHD.