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In this study, we report the synthesis of copper ion containing polyisocyanurate-urea xerogels (Cu-PIU) by reaction of organic monomers containing isocyanate functional groups catalyzed by copper chloride. Wet gels were dried under ambient temperature and pressure conditions to yield Cu-PIU xerogels which is a simple and economic process. The obtained xerogels were found to have bulk and skeletal densities of 1.2 and 1.4 g/cc respectively. The metal ions were found to catalyze the reaction of polyisocyanurate-urea by initiating the trimerization of isocyanate to isocyanurate; additionally, the water present in the hydrated metal salts was found to form urea linkages by reacting with the isocyanate functional groups. The copper containing polyisocyanurate-urea xerogels and coatings were found to exert excellent antibacterial properties on both 'Staphylococcus Aureus' (Gram positive) and 'Escherichia Coli' (Gram negative) bacteria through the zone of inhibition method. Moreover, the prepared polymer composites and metal-ion doped polymeric xerogels exhibited good bioadhesion and bio-compatibility towards MG63 cells which indicates the non-toxic nature of the materials and hence they can be used in the biomedical field. [ABSTRACT FROM AUTHOR]

Boron-doped graphene quantum dots (B-GQDs) have been synthesized via a microwave reactor assisted process from bulk boron carbide (B4C) crystals and they are shown to exhibit enhanced photoactivity. The B-GQDs are found to have an average lateral width of ∼6 ± 2 nm, and thickness of ∼0.2–0.3 nm. Nano ZnO is incorporated into these B-GQDs to prepare a B-GQDs-ZnO composite based high-performance photo-anode for Dye-Sensitized Solar Cells (DSSCs). The results showed the highest power conversion efficiency of ∼3.7% with these new composite based DSSCs, showing the potential of this composite in real cell applications. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we report, a hybrid of mixed valent cobalt ludwigite (Co3BO5) and reduced‐multiwalled carbon nanotubes (R‐MWCNTs) as an outstanding oxygen evolution reaction (OER) electrocatalyst. Interestingly, the composite acts as a potential OER electrocatalyst, displaying a low overpotential of 270 mV @10 mA cm−2, which is lower than that for the state‐of‐the‐art RuO2 catalyst. The remarkable OER performance of the cobalt‐ludwigite is attributed to its basic distorted open crystal structure, which has a relatively high crystal volume, owing to a domain network consisting of edge‐sharing octahedra. Moreover, X‐ray photoelectron spectroscopy clarifies the hybrid of cobalt‐ludwigite and R‐MWCNTs, exhibiting a stable π‐cation‐like interaction between the Co3+ of Co3BO5 rather than Co2+ and neutral π‐ cloud of R‐MWCNTs, which helps in enhancing the conductivity of the system. Thus, the overall performance of the composite stems from the basic crystal structure of the Co3BO5 and the existence of synergistic effects between the R‐MWCNTs on Co3BO5 through π‐cation‐like interaction. Hence, the results of this study might be useful in developing more efficient other ludwigite–carbon OER electrocatalysts as affordable alternatives. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical water oxidation is a dynamic and basal approach for several energy conversion technologies such as solar fuels and metal–air batteries. Herein, we report a novel ‘nitrogen’ (N) enriched interconnected graphene quantum dots (C‐GQDs) as efficient oxygen evolution electrocatalyst, a potential candidate to replace the noble metal OER electrocatalysts. Interestingly, C‐GQDs deliver a current density of 10 mAcm‐2 at 350 mV, a small Tafel slope of 55 mV/dec and outstanding durability which is much superior to the state‐of‐the‐art precious RuO2. More precisely, the unexpected behaviour of graphene quantum dots towards oxygen evolution reaction (OER) is attributed to the interconnection through N‐rich framework (25 %) among the discrete particles. Predominantly, in the pyridine N‐oxide, N acts as nucleophilic site and pyridinic N develops p‐ type doping, responsible for enhanced the OER electrocatalytic activity. The co‐existence of both pyridinic N and pyridine N‐oxide N induces charge redistribution through π‐π delocalization to reduce the *OOH thermodynamic energy barrier. We hope that our study will encourage to develop more efficient electrocatalysts with more effective doping or surface functionalized structure by understanding the dopant nature. [ABSTRACT FROM AUTHOR]

Herein, we report a single step, anionic surfactant-assisted, low temperature-hydrothermal synthetic strategy of CoO nanoparticles anchored on β-Co(OH)2 nanosheets which show a low overpotential (295 mV @ 10 mA cm−2) for the oxygen evolution reaction (OER). They also demonstrate much better kinetic parameters compared to the state-of-the-art RuO2. Interestingly, under the OER operational conditions (in alkaline medium), the topotactic transformation of α-Co(OH)2 to a stable Brucite-like β-Co(OH)2 phase leads to a synergistic interaction between the β-Co(OH)2 sheets on the CoO nanoparticles for enhancing the OER electrocatalytic activity. [ABSTRACT FROM AUTHOR]

High cost of benchmarked platinum-based electro-catalyst restricts their extensive usage in various energy technologies such as fuel cell. To overcome this, we report a simple, economical and facile synthesis route for a series of edge-defective nitrogen doped graphene (NG) from graphene oxide in the presence of melamine as a nitrogen precursor. The oxygen reduction reaction activity of NG in alkaline medium is studied with varying GO to melamine ratio to optimize the N-content in the graphene sheet. Cyclic voltammograms and linear sweep voltammograms have been recorded in N2/O2 saturated 0.1 M aqueous KOH electrolyte. It is observed that N-doped graphene exhibits a favorable formation of hydroxide ions through a four electron transfer process as confirmed from both rotating disk and rotating ring-disk electrode measurements. The stability of the optimized NG catalyst is ascertained by cycling the potential between -0.8 and 0.2 V vs. Ag/AgCl upto10,000 potential cycles and found to have better durability in comparison to the commercial Pt/C catalyst. The resultant N-doped graphene is used as cathode catalyst for fabricating membrane electrode assembly (MEA) and the performance is evaluated in an anion exchange membrane fuel cells (AEMFCs) at 60°C under ambient pressure. [ABSTRACT FROM AUTHOR]

Hydroxyapatite [HAP] and tricalcium phosphate [ß-TCP] are a class of calcium phosphate related ceramic materials that are widely used in tissue regeneration and biomedical applications owing to their excellent bioactivity and biocompatibility. In this investigation, nanocrystalline pure HAP was prepared via sol–gel method by incorporating snail shell as calcium precursor with different phosphorus sources such as triethyl phosphate/phosphite (without using any additives like pH maintaining solutions or gelling agents). Nanocrystalline HAP and biphasic calcium phosphate (HAP + ß TCP) were prepared from triethyl phosphate and triethyl phosphite precursors, respectively. The prepared material was further characterized by powder XRD, IR, Raman spectroscopy, and thermo-gravimetrical analysis to confirm the phase purity, functional groups, and thermal stability. SEM coupled with EDAX was also used to examine the size, shape of particles, and elemental composition of Ca to P ratio in the material. Different phosphorus based HAP has shown rod and spherical shaped surface morphology which was further confirmed by TEM analysis. MTT assay was performed using NIH-3T3 fibroblast cell lines which indicated that the viability was not affected in various concentrations of pure nanocrystalline HAP (12.5–100 µg/ml). This study confirms the improved biocompatibility of biowaste converted HAP which would have implications in biomedical applications. [ABSTRACT FROM PUBLISHER]

A single material that can perform water oxidation and oxygen reduction reactions (ORR), also called bifunctional catalyst, represents a novel concept that emerged from recent materials research and that has led to applications in new-generation energy-storage systems, such as regenerative fuel cells. Here, metal/metal-oxide free, doped graphene derived from rhombohedral boron carbide (B4C) is demonstrated to be an effective bifunctional catalyst for the first time. B4C, one of the hardest materials in nature next to diamond and cubic boron nitride, is converted and separated in bulk to form heteroatom (boron, B) doped graphene (BG, yield ≈7% by weight, after the first cycle). This structural conversion of B4C to graphene is accompanied by in situ boron doping and results in the formation of an electrochemically active material from a non-electrochemically active material, broadening its potential for application in various energy-related technologies. The electrocatalytic efficacy of BG is studied using various voltammetric techniques. The results show a four-electron transfer mechanism as well as a high methanol tolerance and stability towards ORR. The results are comparable to those from commercial 20 wt% Pt/C in terms of performance. Furthermore, the bifunctionality of the BG is also demonstrated by its performance in water oxidation. [ABSTRACT FROM AUTHOR]