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Conductive polymer poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) exhibits a tunable conductivity ranging from 0.1 to 4380 S·cm-1 under different doping and/or dedoping strategies. However, the dependence of macroscopic electrical properties on the evolution of the microstructure is not clearly understood. This is the first study that systematically investigated the spatial arrangement of the ordered and disordered phases in PEDOT/PSS nanofilms by bright-field (BF), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) combined with electron energy loss spectroscopy (EELS) and element-thickness mapping. Our observations clarify how amorphous PSS hinders electrical transport at various length scales in the PEDOT/PSS films. Moreover, the mechanism for an enhancement in 3 orders of magnitude in electrical conductivity was proved by TEM investigation, which is mainly due to a more uniform dispersion by dedoping that opens PEDOT nanoparticle clusters in PEDOT/PSS films. Our microstructural and electrical studies show that the change in spatial arrangement and interaction of small PEDOT domains plays a considerable role in the final electron transport. [ABSTRACT FROM AUTHOR]

In this work, a relatively new class of materials, rare earth (RE) based high entropy oxides (HEO) are discussed in terms of the evolution of the oxygen vacant sites (O v ) content in their structure as the composition changes from binary to HEO using both experimental and computational tools; the composition of HEO under focus is the CeLaPrSmGdO due to the importance of ceria-related (fluorite) materials to catalysis. To unveil key features of quinary HEO structure, ceria-based binary CePrO and CeLaO compositions as well as SiO 2 , the latter as representative nonreducible oxide, were used and compared as supports for Ru (6 wt % loading). The role of the O v in the HEO is highlighted for the ammonia production with particular emphasis on the N 2 dissociation step (N 2(ads) → N ads ) over a HEO; the latter step is considered the rate controlling one in the ammonia production. Density functional theory (DFT) calculations and 18 O 2 transient isotopic experiments were used to probe the energy of formation, the population, and the easiness of formation for the O v at 650 and 800 °C, whereas Synchrotron EXAFS, Raman, EPR, and XPS probed the Ce-O chemical environment at different length scales. In particular, it was found that the particular HEO composition eases the O v formation in bulk, in medium (Raman), and in short (localized) order (EPR); more O v population was found on the surface of the HEO compared to the binary reference oxide (CePrO). Additionally, HEO gives rise to smaller and less sharp faceted Ru particles, yet in stronger interaction with the HEO support and abundance of Ru-O-Ce entities (Raman and XPS). Ammonia production reaction at 400 °C and in the 10-50 bar range was performed over Ru/HEO, Ru/CePrO, Ru/CeLaO, and Ru/SiO 2 catalysts; the Ru/HEO had superior performance at 10 bar compared to the rest of catalysts. The best performing Ru/HEO catalyst was activated under different temperatures (650 vs 800 °C) so to adjust the O v population with the lower temperature maintaining better performance for the catalyst. DFT calculations showed that the HEO active site for N adsorption involves the O v site adjacent to the adsorption event.

In line with current research goals involving water splitting for hydrogen production, this work aims to develop a noble-metal-free electrocatalyst for a superior hydrogen evolution reaction (HER). A single-step interfacial activation of Ti 3 C 2 T x MXene layers was employed by uniformly growing embedded WS 2 two-dimensional (2D) nanopetal-like sheets through a facile solvothermal method. We exploited the interactions between WS 2 nanopetals and Ti 3 C 2 T x nanolayers to enhance HER performance. A much safer method was adopted to synthesize the base material, Ti 3 C 2 T x MXene, by etching its MAX phase through mild in situ HF formation. Consequently, WS 2 nanopetals were grown between the MXene layers and on edges in a one-step solvothermal method, resulting in a 2D-2D nanocomposite with enhanced interactions between WS 2 and Ti 3 C 2 T x MXene. The resulting 2D-2D nanocomposite was thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses before being utilized as working electrodes for HER application. Among various loadings of WS 2 into MXene, the 5% WS 2 -Ti 3 C 2 T x MXene sample exhibited the best activity toward HER, with a low overpotential value of 66.0 mV at a current density of -10 mA cm -2 in a 1 M KOH electrolyte and a remarkable Tafel slope of 46.7 mV·dec -1 . The intercalation of 2D WS 2 nanopetals enhances active sites for hydrogen adsorption, promotes charge transfer, and helps attain an electrochemical stability of 50 h, boosting HER reduction potential. Furthermore, theoretical calculations confirmed that 2D-2D interactions between 1T/2H-WS 2 and Ti 3 C 2 T x MXene realign the active centers for HER, thereby reducing the overpotential barrier.

Biowaste utilization as a carbon source and its transformation into porous carbons have been of great interest to promote environmental remediation owing to biowaste's cost-effectiveness and useful physicochemical properties. In this work, crude glycerol (CG) residue from waste cooking oil transesterification was employed to fabricate mesoporous crude glycerol-based porous carbons ( m CGPCs) using mesoporous silica (KIT-6) as a template. The obtained m CGPCs were characterized and compared to commercial activated carbon (AC) and CMK-8, a carbon material prepared using sucrose. The study aimed to evaluate the potential of m CGPC as a CO 2 adsorbent and demonstrated its superior adsorption capacity compared to AC and comparable to CMK-8. The X-ray diffraction (XRD) and Raman results clearly depicted the structure of carbon nature with (002) and (100) planes and defect (D) and graphitic (G) bands, respectively. The specific surface area, pore volume, and pore diameter values confirmed the mesoporosity of m CGPC materials. The transmission electron microscopy (TEM) images also clearly revealed the porous nature with the ordered mesopore structure. The m CGPCs, CMK-8, and AC materials were used as CO 2 adsorbents under optimized conditions. The m CGPC adsorption capacity (1.045 mmol/g) is superior to that of AC (0.689 mmol/g) and still comparable to that of CMK-8 (1.8 mmol/g). The thermodynamic analyses of the adsorption phenomena are also carried out. This work demonstrates the successful synthesis of a mesoporous carbon material using a biowaste (CG) and its application as a CO 2 adsorbent., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The advances in material science along with the development of fabrication techniques have enabled the realization of thin-film-based electronics on active substrates. This has substantially enhanced and supported the deployment of electronic devices in several emerging applications with flexible functionality. In this work, we report a novel fabrication of graphene oxide (GO)-based memristor devices on an active/shrinkable substrate. The standard lithography process is used to fabricate planar Au-rGO-Au devices on a polymer substrate that has the ability to shrink at a certain temperature (i.e., 170 °C). Upon heating, the devices are shrunk to 50% of their original size. A detailed electrical characterization has been carried out to study the switching behavior of the fabricated devices before and after shrinking. The results prove that upon shrinking, the device preserves its switching ability with enhanced electrical parameters (i.e., switching voltage). Also, material characterization performed for the deposited GO on the active substrate shows improved properties of the GO film due to the enhanced arrangement of GO flakes after shrinking. The novel approach proposed in this work provides new insights into and offers the ability to scale thin-film electronics postfabrication and thus overcome some of the device scaling challenges due to manufacturing limitations. It also unfolds a new path for the realization of GO-based electronic devices with improved electrical properties, which is a crucial aspect of the development of highly flexible and lightweight green electronics., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Doped ceria-based metal oxides are widely used as supports and stand-alone catalysts in reactions where CO 2 is involved. Thus, it is important to understand how to tailor their CO 2 adsorption behavior. In this work, steering the CO 2 activation behavior of Ce-La-Cu-O ternary oxide surfaces through the combined effect of chemical and mechanical strain was thoroughly examined using both experimental and ab initio modeling approaches. Doping with aliovalent metal cations (La 3+ or La 3+ /Cu 2+ ) and post-synthetic ball milling were considered as the origin of the chemical and mechanical strain of CeO 2 , respectively. Experimentally, microwave-assisted reflux-prepared Ce-La-Cu-O ternary oxides were imposed into mechanical forces to tune the structure, redox ability, defects, and CO 2 surface adsorption properties; the latter were used as key descriptors. The purpose was to decouple the combined effect of the chemical strain (ε C ) and mechanical strain (ε M ) on the modification of the Ce-La-Cu-O surface reactivity toward CO 2 activation. During the ab initio calculations, the stability (energy of formation, E O v f ) of different configurations of oxygen vacant sites (O v ) was assessed under biaxial tensile strain (ε > 0) and compressive strain (ε < 0), whereas the CO 2 -philicity of the surface was assessed at different levels of the imposed mechanical strain. The E O v f values were found to decrease with increasing tensile strain. The Ce-La-Cu-O(111) surface exhibited the lowest E O v f values for the single subsurface sites, implying that O v may occur spontaneously upon Cu addition. The mobility of the surface and bulk oxygen anions in the lattice contributing to the O v population was measured using 16 O/ 18 O transient isothermal isotopic exchange experiments; the maximum in the dynamic rate of 16 O 18 O formation, R max ( 16 O 18 O), was 13.1 and 8.5 μmol g -1 s -1 for pristine (chemically strained) and dry ball-milled (chemically and mechanically strained) oxides, respectively. The CO 2 activation pathway (redox vs associative) was experimentally probed using in situ diffuse reflectance infrared Fourier transform spectroscopy. It was demonstrated that the mechanical strain increased up to 6 times the CO 2 adsorption sites, though reducing their thermal stability. This result supports the mechanical actuation of the "carbonate"-bound species; the latter was in agreement with the density functional theory (DFT)-calculated C-O bond lengths and O-C-O angles. Ab initio studies shed light on the CO 2 adsorption energy ( E ads ), suggesting a covalent bonding which is enhanced in the presence of doping and under tensile strain. Bader charge analysis probed the adsorbate/surface charge distribution and illustrated that CO 2 interacts with the dual sites (acidic and basic ones) on the surface, leading to the formation of bidentate carbonate species. Density of states (DOS) studies revealed a significant E g drop in the presence of double O v and compressive strain, a finding with design implications in covalent type of interactions. To bridge this study with industrially important catalytic applications, Ni-supported catalysts were prepared using pristine and ball-milled oxides and evaluated for the dry reforming of methane reaction. Ball milling was found to induce modification of the metal-support interface and Ni catalyst reducibility, thus leading to an increase in the CH 4 and CO 2 conversions. This study opens new possibilities to manipulate the CO 2 activation for a portfolio of heterogeneous reactions.

CO elimination through oxidation over highly active and cost-effective catalysts is a way forward for many processes of industrial and environmental importance. In this study, doped CeO 2 with transition metals (TM = Cu, Co, Mn, Fe, Ni, Zr, and Zn) at a level of 20 at. % was tested for CO oxidation. The oxides were prepared using microwave-assisted sol-gel synthesis to improve catalyst's performance for the reaction of interest. The effect of heteroatoms on the physicochemical properties (structure, morphology, porosity, and reducibility) of the binary oxides M-Ce-O was meticulously investigated and correlated to their CO oxidation activity. It was found that the catalytic activity (per gram basis or TOF, s -1 ) follows the order Cu-Ce-O > Ce-Co-O > Ni-Ce-O > Mn-Ce-O > Fe-Ce-O > Ce-Zn-O > CeO 2 . Participation of mobile lattice oxygen species in the CO/O 2 reaction does occur, the extent of which is heteroatom-dependent. For that, state-of-the-art transient isotopic 18 O-labeled experiments involving 16 O/ 18 O exchange followed by step-gas CO/Ar or CO/O 2 /Ar switches were used to quantify the contribution of lattice oxygen to the reaction. SSITKA-DRIFTS studies probed the formation of carbonates while validating the Mars-van Krevelen (MvK) mechanism. Scanning transmission electron microscopy-high-angle annular dark field imaging coupled with energy-dispersive spectroscopy proved that the elemental composition of dopants in the individual nanoparticle of ceria is less than their composition at a larger scale, allowing the assessment of the doping efficacy. Despite the similar structural features of the catalysts, a clear difference in the O lattice mobility was also found as well as its participation (as expressed with the α descriptor) in the reaction, following the order α Cu > α Co > α Mn > α Zn . Kinetic studies showed that it is rather the pre-exponential (entropic) factor and not the lowering of activation energy that justifies the order of activity of the solids. DFT calculations showed that the adsorption of CO on the Cu-doped CeO 2 surface is more favorable (-16.63 eV), followed by Co, Mn, Zn (-14.46, -4.90, and -4.24 eV, respectively), and pure CeO 2 (-0.63 eV). Also, copper compensates almost three times more charge (0.37 e - ) compared to Co and Mn, ca. 0.13 e - and 0.10 e - , respectively, corroborating for its tendency to be reduced. Surface analysis (X-ray photoelectron spectroscopy), apart from the oxidation state of the elements, revealed a heteroatom-ceria surface interaction (O a species) of different extents and of different populations of O a species.

Growing III-nitride nanowires on 2D materials is advantageous, as it effectively decouples the underlying growth substrate from the properties of the nanowires. As a relatively new family of 2D materials, MXenes are promising candidates as III-nitride nanowire nucleation layers capable of providing simultaneous transparency and conductivity. In this work, we demonstrate the direct epitaxial growth of GaN nanowires on Ti 3 C 2 MXene films. The MXene films consist of nanoflakes spray coated onto an amorphous silica substrate. We observed an epitaxial relationship between the GaN nanowires and the MXene nanoflakes due to the compatibility between the triangular lattice of Ti 3 C 2 MXene and the hexagonal structure of wurtzite GaN. The GaN nanowires on MXene show good material quality and partial transparency at visible wavelengths. Nanoscale electrical characterization using conductive atomic force microscopy reveals a Schottky barrier height of ∼330 meV between the GaN nanowire and the Ti 3 C 2 MXene film. Our work highlights the potential of using MXene as a transparent and conductive preorienting nucleation layer for high-quality GaN growth on amorphous substrates.

Aqueous Zn-ion batteries present low-cost, safe, and high-energy battery technology but suffer from the lack of suitable cathode materials because of the sluggish intercalation kinetics associated with the large size of hydrated zinc ions. Herein we report an effective and general strategy to transform inactive intercalation hosts into efficient Zn 2+ storage materials through intercalation energy tuning. Using MoS 2 as a model system, we show both experimentally and theoretically that even hosts with an originally poor Zn 2+ diffusivity can allow fast Zn 2+ diffusion. Through simple interlayer spacing and hydrophilicity engineering that can be experimentally achieved by oxygen incorporation, the Zn 2+ diffusivity is boosted by 3 orders of magnitude, effectively enabling the otherwise barely active MoS 2 to achieve a high capacity of 232 mAh g -1 , which is 10 times that of its pristine form. The strategy developed in our work can be generally applied for enhancing the ion storage capacity of metal chalcogenides and other layered materials, making them promising cathodes for challenging multivalent ion batteries.

Porous materials with molecular-scale ordering have attracted major attention mainly because of the possibility to engineer their pores for selective applications. Periodic mesoporous organosilica is a class of hybrid materials where self-assembly of the organic linkers provides a crystal-like pore wall. However, unlike metal coordination, specific geometries cannot be predicted because of the competitive and dynamic nature of noncovalent interactions. Herein, we study the influence of competing noncovalent interactions in the pore walls on the biodegradation of organosilica frameworks for drug delivery application. These results support the importance of studying self-assembly patterns in hybrid frameworks to better engineer the next generation of dynamic or "soft" porous materials., Competing Interests: The authors declare no competing financial interest.

Ni and NiSn supported on zirconia (ZrO 2 ) and on indium (In)-incorporated zirconia (InZrO 2 ) catalysts were prepared by a wet chemical reduction route and tested for hydrogenation of CO 2 to methanol in a fixed-bed isothermal flow reactor at 250 °C. The mono-metallic Ni (5%Ni/ZrO 2 ) catalysts showed a very high selectivity for methane (99%) during CO 2 hydrogenation. Introduction of Sn to this material with the following formulation 5Ni5Sn/ZrO 2 (5% Ni-5% Sn/ZrO 2 ) showed the rate of methanol formation to be 0.0417 μmol/(g cat ·s) with 54% selectivity. Furthermore, the combination NiSn supported on InZrO 2 (5Ni5Sn/10InZrO 2 ) exhibited a rate of methanol formation 10 times higher than that on 5Ni/ZrO 2 (0.1043 μmol/(g cat ·s)) with 99% selectivity for methanol. All of these catalysts were characterized by X-ray diffraction, high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy, CO 2 -temperature-programmed desorption, and density functional theory (DFT) studies. Addition of Sn to Ni catalysts resulted in the formation of a NiSn alloy. The NiSn alloy particle size was kept in the range of 10-15 nm, which was evidenced by HRTEM study. DFT analysis was carried out to identify the surface composition as well as the structural location of each element on the surface in three compositions investigated, namely, Ni 28 Sn 27 , Ni 18 Sn 37 , and Ni 37 Sn 18 bimetallic nanoclusters, and results were in agreement with the STEM and electron energy-loss spectroscopy results. Also, the introduction of "Sn" and "In" helped improve the reducibility of Ni oxide and the basic strength of catalysts. Considerable details of the catalytic and structural properties of the Ni, NiSn, and NiSnIn catalyst systems were elucidated. These observations were decisive for achieving a highly efficient formation rate of methanol via CO 2 by the H 2 reduction process with high methanol selectivity., Competing Interests: The authors declare no competing financial interest.

The Magnéli phase V 6 O 11 was synthesized in gram amounts from a powder mixture of V 6 O 11 /V 7 O 13 and vanadium metal, using the spark plasma sintering (SPS) technique. Its structure was determined with synchrotron X-ray powder diffraction data from a phase-pure sample synthesized by conventional solid-state synthesis. A special feature of Magnéli-type oxides is a combination of crystallographic shear and intrinsic disorder that leads to relatively low lattice thermal conductivities. SPS prepared V 6 O 11 has a relatively low thermal conductivity of κ = 2.72 ± 0.06 W (m K) -1 while being a n-type conductor with an electrical conductivity of σ = 0.039 ± 0.005 (μΩ m) -1 , a Seebeck coefficient of α = -(35 ± 2) μV K -1 , which leads to a power factor of PF = 4.9 ± 0.8 × 10 -5 W (m K 2 ) -1 at ∼600 K. Advances in the application of Magnéli phases are mostly hindered by synthetic and processing challenges, especially when metastable and nanostructured materials such as V 6 O 11 are involved. This study gives insight into the complications of SPS-assisted synthesis of complex oxide materials, provides new information about the thermal and electrical properties of vanadium oxides at high temperatures, and supports the concept of reducing the thermal conductivity of materials with structural building blocks such as crystallographic shear (CS) planes.

Bimetallic nanoparticles have been the subject of numerous research studies in the nanotechnology field, in particular for catalytic applications. Control of the size, morphology, and composition has become a key challenge due to the relationship between these parameters and the catalytic behavior of the particles in terms of activity, selectivity, and stability. Here, we present a one-pot air synthesis of 2 nm Ni 9 Pt 1 nanoparticles with a narrow size distribution. Control of the size and composition of the alloy particles is achieved at ambient temperature, in the aqueous phase, by the simultaneous reduction of nickel and platinum precursors with hydrazine, using a reverse microemulsion system. After deposition on an alumina support, this Ni-rich nanoalloy exhibits unprecedented stability under the harsh conditions of methane dry reforming.

We study the band discontinuity at the GaN/single-layer (SL) WSe 2 heterointerface. The GaN thin layer is epitaxially grown by molecular beam epitaxy on chemically vapor deposited SL-WSe 2 /c-sapphire. We confirm that the WSe 2 was formed as an SL from structural and optical analyses using atomic force microscopy, scanning transmission electron microscopy, micro-Raman, absorbance, and microphotoluminescence spectra. The determination of band offset parameters at the GaN/SL-WSe 2 heterojunction is obtained by high-resolution X-ray photoelectron spectroscopy, electron affinities, and the electronic bandgap values of SL-WSe 2 and GaN. The valence band and conduction band offset values are determined to be 2.25 ± 0.15 and 0.80 ± 0.15 eV, respectively, with type II band alignment. The band alignment parameters determined here provide a route toward the integration of group III nitride semiconducting materials with transition metal dichalcogenides (TMDs) for designing and modeling of their heterojunction-based electronic and optoelectronic devices.

Engineering and scaling-up new materials for better water desalination are imperative to find alternative fresh water sources to meet future demands. Herein, the fabrication of hydrophobic poly(ether imide) composite nanofiber membranes doped with novel ethylene-pentafluorophenylene-based periodic mesoporous organosilica nanoparticles is reported for enhanced and fouling resistant membrane distillation. Novel organosilica nanoparticles were homogeneously incorporated into electrospun nanofiber membranes depicting a proportional increase of hydrophobicity to the particle contents. Direct contact membrane distillation experiments on the organosilica-doped membrane with only 5% doping showed an increase of flux of 140% compared to commercial membranes. The high porosity of organosilica nanoparticles was further utilized to load the eugenol antimicrobial agent which produced a dramatic enhancement of the antibiofouling properties of the membrane of 70% after 24 h.

Efficient water splitting requires highly active, earth-abundant, and robust catalysts. Monometallic phosphides such as Ni 2 P have been shown to be active toward water splitting. Our theoretical analysis has suggested that their performance can be further enhanced by substitution with extrinsic metals, though very little work has been conducted in this area. Here we present for the first time a novel PH 3 plasma-assisted approach to convert NiCo hydroxides into ternary NiCoP. The obtained NiCoP nanostructure supported on Ni foam shows superior catalytic activity toward the hydrogen evolution reaction (HER) with a low overpotential of 32 mV at -10 mA cm -2 in alkaline media. Moreover, it is also capable of catalyzing the oxygen evolution reaction (OER) with high efficiency though the real active sites are surface oxides in situ formed during the catalysis. Specifically, a current density of 10 mA cm -2 is achieved at overpotential of 280 mV. These overpotentials are among the best reported values for non-noble metal catalysts. Most importantly, when used as both the cathode and anode for overall water splitting, a current density of 10 mA cm -2 is achieved at a cell voltage as low as 1.58 V, making NiCoP among the most efficient earth-abundant catalysts for water splitting. Moreover, our new synthetic approach can serve as a versatile route to synthesize various bimetallic or even more complex phosphides for various applications.

Bridged silsesquioxane nanocomposites with tunable morphologies incorporating o-nitrophenylene-ammonium bridges are described. The systematic screening of the sol-gel parameters allowed the material to reach the nanoscale with controlled dense and hollow structures of 100-200 nm. The hybrid composition of silsesquioxanes with 50% organic content homogeneously distributed in the nanomaterials endowed them with photoresponsive properties. Light irradiation was performed to reverse the surface charge of nanoparticles from +46 to -39 mV via a photoreaction of the organic fragments within the particles, as confirmed by spectroscopic monitorings. Furthermore, such nanoparticles were applied for the first time for the on-demand delivery of plasmid DNA in HeLa cancer cells via light actuation.