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A sensing materiel based on calix[4]arene molecules is electrochemically deposited on ITO electrode coated. A brown film was electrodeposited at a potential Eimp = -1.00 V versus SCE in acetonitrile solvent, however in dichloromethane solvent, a bluish film auto-assembled on the ITO electrode coated at a potential Eimp = -0.65 V versus SCE. Both films are subsequently analyzed by cyclic voltammetry and UV-Vis spectroscopy. This investigation shows that in acetonitrile solvent, the charge-transfer complex, calix[4]arenequinhydrone was formed in electrolytic solution and it was not self-assembled on the ITO electrode. The related UV-Vis spectrum shows a single absorption band towards a wavelength about 350 nm. The optical behaviour of the blue film shows two absorption bands: the first one appears on the first absorption band of the acceptor at 305 nm and the second one in the visible range at 502 nm. The band situated in the visible range correspond to a well-defined charge-transfer band indicating the presence of the charge-transfer complex, the calix[4]arenequinhydrone.

We have prepared different hybrid polymer-phthalocyanine materials by solution processing, starting from two sulfonated phthalocyanines, s-CoPc and CuTsPc, and polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), poly(acrylic acid-co-acrylamide) (PAA-AM), poly(diallyldimethylammonium chloride) (PDDA) and polyaniline (PANI) as polymers. We also studied the response to ammonia (NH3) of resistors prepared from these sensing materials. The solvent casted films, prepared from s-CoPc and PVP, PEG and PAA-AM, were highly insulating and very sensitive to the relative humidity (RH) variation. The incorporation of s-CoPc in PDDA by means of layer-by-layer (LBL) technique allowed to stabilize the film, but was too insulating to be interesting. We also prepared PANI-CuTsPc hybrid films by LBL technique. It allowed a regular deposition as evidenced by the linear increase of the absorbance at 688 nm as a function of the number of bilayers. The sensitivity to ammonia (NH3) of PANi-CuTsPc resistors was very high compared to that of individual materials, giving up to 80% of current decrease when exposed to 30 ppm NH3. Contrarily to what happens with neutral polymers, in PANI, CuTsPc was stabilized by strong electrostatic interactions, leading to a stable response to NH3, whatever the relative humidity in the range 10%-70%. Thus, the synergy of PANI with ionic macrocycles used as counteranions combined with their simple aqueous solution processing opens the way to the development of new gas sensors capable of operating in real world conditions.

The adoption of green hydrogen economy is an indispensable necessity in the current global scenario of environment and energy security. In this endeavor, ammonia is poised to play a key vector of hydrogen to mitigate the challenges arising from transportation, storage and safety. Besides containing a high volumetric and gravimetric hydrogen density, NH3 decomposition into H2 for onsite utilization as a distributed energy source is devoid of greenhouse gases production. In this endeavor, significant technological advancements have been made for in situ production of H2 from NH3 decomposition and the use of NH3 in fuel cell devices to produce electricity. The ammonia decomposition methods to produce H2 mainly involve thermocatalytic, oxidative, electrocatalytic and photocatalytic, among which the catalyst assisted thermal cracking of NH3 has been widely investigated. The research progress in electrolysis of NH3 has been notable in the last couple of years and provides a low‐cost alternative to produce H2 at room temperature. In the area of device development, solid oxide fuel cells (SOFC) have witnessed rapid development in the performances and stability, as ammonia is completely decomposed into H2 and N2 at high operating temperature above ~700 °C. [ABSTRACT FROM AUTHOR]

Understanding the structure and origin of catalytic sites at the nanometer/subnanometer scale in porous nanomaterials is essential for an efficient and durable catalyst design. Herein, chemically pure nanoporous gold (NPG) having a hierarchically porous network is electrochemically synthesized, and its microstructure is investigated by electron microscopies, electrochemical methods, and ab initio simulations to unravel the identification of catalytic sites for ascorbic acid (AA) electrochemical oxidation. Experimental characterizations reveal a highly porous NPG film containing polycrystalline and interconnected dendrite fractals. The film growth follows a unique pattern such that at the beginning of the film growth, Au grains are smaller, which at the later growth stage become larger and expose low-index facets and structural defects such as dislocation of Au atoms, atomic steps, and kinks. Such structural defects and facet evolutions in the NPG film cause a remarkable electrocatalytic effect toward the electrochemical oxidation of AA, which is interpreted based on density function theory (DFT) simulation. The simulation predicts stronger binding of AA on the low-indexed Au facets and grain boundaries, leading to a larger electronic charge transfer from AA to the Au atoms. In particular, grain boundary regions provide vacancy-like sites, in which part of AA locks itself, forming a stronger bond with a Au atom of partial covalent character. The low catalytic activity of the thermodynamically stable (111) facet is assigned to its flat topography, over which AA interacts through mainly van der Waals forces, causing weaker binding. [ABSTRACT FROM AUTHOR]

The assembly of hybrid materials combining a pure sp3‐C platform from nano‐and microcrystals of molecularly‐defined nanometer‐sized functionalized diamondoids (nanodiamonds) coated with a gold transition metal nanolayer is conducted from the gas phase, following a two‐steps vapor phase dry construction process. By using first the controlled vapor phase self‐assembly of primary phosphine diamantane derivatives, followed by a chemical vapor decomposition of a suited gold organometallic complex the synthesis of the nanocomposite Au@H2P–DiamOH 2 is achieved. The gold deposit surface analysis reveals the formation of a Au–P covalent bonding, which excludes the formation of phosphine oxide, as confirmed at higher depth into the nanocomposite by Hard X‐ray Photoelectron Spectroscopy analysis (HaXPES). The thickness d of the gold layers deposited onto the surface of diamondoids is estimated to be around d = 0.8 ± 10% nm from XPS data, which allows combining the composite Au@H2P–DiamOH 2 with ITO interdigitated electrodes, to produce a long‐life, highly stable and reproducible, n‐type behavior sensor for ammonia detection. A relative response (RR) of 150% at 30 ppm and a limit of detection of 6 ppm are measured at room temperature (20 to 25 °C) and at 45% of relative humidity. [ABSTRACT FROM AUTHOR]

This study focuses on the determination of a protocol for the production of a hybrid material composed of a polymer and a macrocyclic complex, namely polystyrene and a tetra-tert-butyl-copper phthalocyanine (Cu[[(tBu).sub.4]Pc]), in order to obtain a layer thickness of about 100 nm and a controlled porosity in a highly reproducible way. Several methods were implemented and their reproducibility was evaluated through elements of characterization such as optical microscopy, atomic force microscopy and scanning electron microscopy. POLYM. ENG. SCI., 53:524-530, 2013. (D 2012 Society of Plastics Engineers, INTRODUCTION The functioning of gas sensors is based on the properties of the interactions between gases and surface materials (1). These interactions are classified into two categories according to the [...]