Superior Electron Transport Properties Research Articles

Tellurium doped sulfurized polyacrylonitrile nanoflower for high-energy-density, long-lifespan sodium-sulfur batteries

Sodium-sulfur (Na−S) batteries are promising energy storage devices for large-scale applications due to their high-energy-density and abundant material reserve. However, the practical implementation of room temperature (RT) Na−S batteries faces challenges, including low-energy-density and limited lifespan, particularly attributed to the properties of sulfurized polyacrylonitrile (SPAN). In this study, we address these challenges by introducing tellurium doping into SPAN nanoflowers, enhancing their performance for Na−S batteries. The resulting material exhibits high sulfur loading as well as superior electron and ion transport properties, leading to enhanced redox kinetics and improved battery performance. The tellurium-doped SPAN nanoflower electrode delivers an exceptional composite capacity of 700 mAh g−1 at 0.1 C and demonstrates stable cycling over 2400 cycles with minimal capacity fade (0.01 % average fading rate). Even under challenging conditions (24.0 mg cm−2, E/S=5 mg μLS−1, N/P=2.1), the Na−S battery achieves a high areal capacity of 16.1 mAh cm−2, resulting in an impressive energy density of 340.9 Wh kg–1 based on cathode and anode. This work presents a promising approach to designing high-energy-density, long-lifespan RT Na−S batteries, with potential applications for other metal-sulfur battery systems.

CuInS2/Red Phosphorus Nanosheet Interleaved Heterostructures with Improved Interfacial Charge Transfer for Photoelectrochemical Aptasensing.

Accelerating the migration of interfacial carriers in heterojunctions is crucial for achieving highly sensitive photoelectrochemical (PEC) sensing. In this study, we developed three-dimensional (3D)/two-dimensional (2D) CuInS2/red phosphorus nanosheet (CuInS2/RP NS) n-n heterojunction functional materials with enhanced interfacial charge transfer capabilities for PEC sensing. The 3D CuInS2 serves as a conductive layer, providing excellent electronic conductivity and superior electron absorption and transport properties. In contrast, the ultrathin RP NS acts as a transport layer that enhances carrier mobility. The 3D/2D heterojunction ensures a large interface contact surface, shortening the carrier transport distance. A well-aligned band position generates a substantial built-in electric field, providing a significant driving force for efficient carrier separation and migration, thereby improving response sensitivity. A PEC aptamer sensor was constructed based on the synthesized heterostructure for ciprofloxacin detection. The detection limit of the CuInS2/RP NS aptamer sensor for ciprofloxacin is 2.03 × 10-15 mg·mL-1, with a linear range from 1.0 × 10-14 to 1.0 × 10-5 mg·mL-1. This work presents a strategy for enhancing the photoelectric response by modulating the interface structure of heterojunctions, thereby opening new prospects for the application of highly sensitive PEC sensors in antibiotic detection.

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS2/MoS2 Heterojunctions.

Two-dimensional transition metal dichalcogenides (2D TMDCs) are considered promising alternatives to Si as channel materials because of the possibility of retaining their superior electronic transport properties even at atomic body thicknesses. However, the realization of high-performance 2D TMDC field-effect transistors remains a challenge owing to Fermi-level pinning (FLP) caused by gap states and the inherent high Schottky barrier height (SBH) within the metal contact and channel layer. This study demonstrates that high-quality van der Waals (vdW) heterojunction-based contacts can be formed by depositing semimetallic TiS2 onto monolayer (ML) MoS2. After confirming the successful formation of a TiS2/ML MoS2 heterojunction, the contact properties of vdW semimetal TiS2 were thoroughly investigated. With clean interfaces of the TiS2/ML MoS2 heterojunctions, atomic-layer-deposited TiS2 can induce gap-state saturation and suppress FLP. Consequently, compared with conventional evaporated metal electrodes, the TiS2/ML MoS2 heterojunctions exhibit a lower SBH of 8.54 meV and better contact properties. This, in turn, substantially improves the overall performance of the device, including its on-current, subthreshold swing, and threshold voltage. Furthermore, we believe that our proposed strategy for vdW-based contact formation will contribute to the development of 2D materials used in next-generation electronics.

Catalytic co-pyrolysis of waste tea residue and waste plastics to carbon nanomaterials: Catalyst support, reaction temperature and product application

The search for cost-effective, high-performance catalysts is crucial in catalytic co-pyrolysis. Different Fe-Mo@X catalysts (X = Al2O3, MgO) and reaction temperatures (600 ℃, 700 ℃, 800 ℃, 900 ℃) were tested to optimize hydrogen production and carbon quality while also exploring CNTs degradation performance. The results indicate that both catalyst type and operating parameters are highly dependent on the growth of carbon nanotubes and hydrogen. The FeMo@Al2O3 catalyst exhibits superior catalytic activity attributed to its more abundant mesoporous structure and higher specific surface area. Specifically, FeMo@Al2O3 achieved the highest yield of carbon nanotubes (84.42%) at 700 ℃, and attained the maximum hydrogen yield (49.57%) at 900 ℃. However, the CNTs synthesized from FeMo@MgO exhibited fewer defects, higher graphitization degree and purity (Raman and TPO). CNTs/MgO significantly enhanced the degradation efficiency of Clothianidin by virtue of their superior electron transport properties and chemical bonding between MgO and CNTs.

Recent advances of Copper- BTC metal-organic frameworks for efficient degradation of organic dye-polluted wastewater: Synthesis, mechanistic insights and future outlook

Water borne emerging pollutants represents a significant challenge confronting the modern society. As a result of excessive use of dyes and pigments by the textile and other industries, substantial amount of these toxic and recalcitrant substances are widely dispersed into the aquatic sources that may raise serious health issues to all life forms besides causing potential disruption to the ecosystem. Treatments of these hazardous and non-biodegradable organic contaminants in wastewater effluents have become a focal point for researchers dedicated to environmental remediation. Notably, Metal organic frameworks (MOFs) and their composites have been reported to be promising materials for tackling such challenges. This review is dedicated to provide a concise overview by consolidating the diverse beneficial attributes of Cu-BTC MOF rendering it as a versatile material with applications spanning diverse domains, focusing on the reactivity, the role of the metal ion and its recent potential for addressing the elimination of toxic textile dye wastes from the wastewater effluent. Furthermore, it also documents the underlying mechanistic pathway governing the degradation mechanism and the superior electron transport property of Cu ̶ BTC, besides painting in detail the existing limitations that hinder their applicability at an industrial platform. Moreover, a set of future research outlooks serving as a roadmap for exploring the potentiality of Cu ̶ BTC MOFs have also been presented.

Towards the Enhanced Lithium‐Ion Batteries by Designing (N, Co, Zr, P) Tetra‐Doped Porous Carbon Anode

AbstractHeteroatom‐doped porous carbons have stable structures, high electron/ion transport efficiencies, and rich electroactive sites, which are of great significance to energy storage devices. The potential synergistic effects arising from the multi‐element doping benefit to improve the electrochemical behavior of porous carbon. In this paper, a facile doping strategy has been proposed to prepare the (N, Co, Zr, P) tetra‐doped porous carbon spheres (PCS) for enhanced lithium‐ion batteries (LIBs). The metal‐organophosphine framework (MOPF) as precursor is synthesized by utilizing riboflavin sodium phosphate as organic ligand coordinating with cobalt and zirconium ions. Through carbonizing MOPF, the (N, Co, Zr, P) tetra‐doped PCS can be obtained. As the anode for LIBs, the (N, Co, Zr, P) tetra‐doped PCS exhibits highly reversible capacity of 761 mAh g−1 at 0.1 A g−1 after 100 cycles, excellent rate performance of 126 mAh g−1 even at a high current density of 2 A g−1. The results feature that the unique 3D structure and superior local electron transport properties of (N, Co, Zr, P) tetra‐doped PCS promote the Li+ diffusion and adsorption, which improve the electrochemical properties. Moreover, the mechanism analysis realizes that the Li+ storage of (N, Co, Zr, P) tetra‐doped PCS is determined by the capacitive behavior at high scan rate, highlighting the significance of the heteroatom doping. Therefore, the (N, Co, Zr, P) tetra‐doped PCS should be considered as prominent candidate for high‐performance LIBs anodes.

Notch-δ-doped InP Gunn diodes for low-THz band applications

The viability of the indium phosphide (InP) Gunn diode as a source for low-THz band applications is analyzed based on a notch-δ-doped structure using the Monte Carlo modeling. The presence of the δ-doped layer could enhance the current harmonic amplitude (A0) and the fundamental operating frequency (f0) of the InP Gunn diode beyond 300 ​GHz as compared with the conventional notch-doped structure for a 600-nm length device. With its superior electron transport properties, the notch-δ-doped InP Gunn diodes outperform the corresponding gallium arsenide (GaAs) diodes with up to 1.35 times higher in f0 and 2.4 times larger in A0 under DC biases. An optimized InP notch-δ-doped structure is estimated to be capable of generating 0.32-W radio-frequency (RF) power at 361 ​GHz. The Monte Carlo simulations predict a reduction of 44% in RF power, when the device temperature is increased from 300 ​K to 500 ​K; however, its operating frequency lies at 280 ​GHz which is within the low-THz band. This shows that the notch-δ-doped InP Gunn diode is a highly promising signal source for low-THz sensors, which are in a high demand in the autonomous vehicle industry.

Near-Field Radiative Heat Transfer between $\\beta-$GeSe monolayers: An ab initio study

ABSTRACT We present a theoretical study of the near-field radiative heat transfer (NFRHT) between two -GeSe monolayers, each at a different temperature. (This is a relevant 2D material with superior electron transport and optical properties compared to black-phosphorus monolayers). The required optical conductivity of the monolayer is calculated using density functional theory including spin-orbit coupling, and using the Perdew-Burke-Erzenhof parametrization. Both the intra and interband transitions are taken into account, as well as the contribution of the optical phonons. This allows us to obtain more realistic predictions of the NFRHT between two monolayers of GeSe. The role of the electron doping concentration and the plasma relaxation frequency is investigated, showing a non-monotonic dependence on the radiative heat transfer with increasing doping, and having an optimal doping where the heat flux is maximize. A strong optical anisotropy in the electric conductivity is obtained from the contribution of both electrons and ions This anisotropy is explored, showing that the relative rotation of two monolayers results in modulation of the NFRHT much larger than previously found for similar 2D materials, like -GeSe. As the angle of rotation between the monolayers increases the total heat transfer decreases. Our analysis demonstrates the relevance of properly taking into account the materialelectronic and ionic contributions.

Amorphous versus crystalline CoSx anchored on CNTs as heterostructured electrocatalysts toward hydrogen evolution reaction

In this work, we have successfully constructed carbon nanotube (CNT)-a-CoSx amorphous heterostructured catalysts using a two-step method. The abundant active sites, superior electron transport properties, and large electrochemically active specific surface area enable amorphous CNT-a-CoSx to exhibit higher hydrogen evolution reaction performance than crystalline CNT-c-CoSx in acidic conditions. To deliver a cathodic current density of 10 mA cm−2, the required overpotential is only 76 mV. No significant performance degradation is observed after 60,000 s of electrochemical durability test. This facile strategy provides technical support for the design and construction of amorphous heterostructured electrocatalysts with high activity and stability for the generation of green hydrogen.

Multihyperuniform long-range order in medium-entropy alloys

Medium-entropy alloys (MEAs) and high-entropy alloys (HEAs) are alloys composed of mixtures of equal or relatively large proportions of three or more elements, and are distinctly different from traditional metallic alloys which contain one or two major components with smaller amounts of other elements. Recently MEAs and HEAs have received extensive research attention because they are found to possess superior mechanical performance, unusual thermal and electronic transport properties, and are resistant to corrosion; however, a fundamental understanding of the atomic structures of these alloys is still largely lacking. In this work, we develop a multihyperuniform (MH) model for disordered medium-entropy alloys (MEAs), in which the normalized infinite-wavelength composition fluctuations for all atomic species are completely suppressed, i.e., a model with hidden long-range order. Using SiGeSn alloy as a representative example, we show that this new type of highly efficient generic computational model results in stable lower-energy states compared to prevailing alloy models with (quasi)random structures, and captures experimentally observed atomic short-range orders in MEAs that are missing in (quasi)random alloy models. The MH model approximately realizes the Vegard’s law, which offers a rule-of-mixture type predictions of the lattice constants and electronic band gap, and thus can be considered as an ideal mixing state. The multihyperuniformity also directly gives rise to enhanced electronic band gaps and superior thermal transport properties at low temperatures compared to (quasi)random structures, which open up novel potential applications in optoelectronics and thermoelectrics. Our MH model can be readily applied and generalized to other medium- and high-entropy alloys (HEAs) with atomic short-range orders, and may account for some of the previously observed major discrepancies between theory and experiment.

Achieving High Responsivity of Photoelectrochemical Solar‐Blind Ultraviolet Photodetectors via Oxygen Vacancy Engineering

AbstractTin oxide (SnO2) is an n‐type wide‐bandgap semiconductor with the merits of superior electron transport properties and good stability, making it an attractive candidate for solar‐blind ultraviolet photodetectors (SBUV PDs). However, it is still challenging to design high‐performance SnO2‐based photoelectrochemical (PEC)‐type SBUV PDs. In this study, oxygen vacancies (OVs) engineering is proposed to manipulate the photoresponse of SnO2 nanosheets (NSs) and high‐performance SnO2‐based PEC SBUV PDs are developed. SnO2 NSs with different OVs are prepared by hydrothermal method with annealing process. PEC PDs consisting of SnO2 NSs annealed at 550 °C show record high responsivity and specific detectivity of 269.40 mA W−1 and 2.38 × 1012 Jones at a bias voltage of 0.2 V, respectively, surpassing all aqueous‐type PEC UV PDs. OVs simultaneously accelerate the carrier recombination in the SnO2 NSs and charge transfer at the interface of the SnO2 NSs and electrolyte, indicating that both excess OVs and too few OVs reduce the PEC photoresponse. Therefore, an appropriate OV's content is vital to designing high‐performance SnO2 NSs PEC PDs. Moreover, the SnO2 NSs PEC PDs have good self‐powered capability, excellent wavelength‐selectivity, multicycle and long‐term stability. The results of this study demonstrate that OVs engineering is a powerful strategy for designing high‐performance SnO2‐based PEC PDs.

Enhanced Photoelectrochemical Performance of Co/TiO2Nanotubes Prepared by Electrodeposition

TiO2nanotube arrays (NTbs) have been widely used in the field of photocatalysis due to their large surface area, good controllability and superior electron transport properties. However, due to its wide bandgap (3.2[Formula: see text]eV), pure TiO2can only be excited by ultraviolet light ([Formula: see text][Formula: see text]nm), leading to low utilization of solar energy. Second, the high recombination rate of the photogenerated electrons and holes ([Formula: see text]/[Formula: see text] pair also reduces the quantum efficiency of TiO2. In order to realize the efficient photocatalytic activity of TiO2nanomaterials, it is necessary to design the TiO2nanomaterials to optimize the utilization of the solar spectrum. In this study, TiO2NTbs were obtained by the anodizing method using titanium foil, and a series of Co/TiO2NTbs were prepared by electrochemical deposition. The effects of the deposition voltage on the physical and photocatalytic properties of the Co/TiO2NTbs were investigated. Results found that the Co/TiO2NTbs had the highest photocurrent density 0.7[Formula: see text]mA/cm2at an electrodeposition time of 60[Formula: see text]s and a voltage of 1[Formula: see text]V, and the photoelectric conversion efficiency was 15.85%, which was approximately 2.8 times that of the pure TiO2NTbs. The degradation rate of Rhodamine B of the Co/TiO2NTbs in 120[Formula: see text]min was 76.3%, whereas that of the pure TiO2NTbs was only 48.7%. The forbidden bandwidth of the Co/TiO2NTbs was reduced to 3.02[Formula: see text]eV, whereas that of the pure TiO2NTbs was 3.2[Formula: see text]eV.

Phase Formation Behavior and Thermoelectric Transport Properties of S-Doped FeSe2-xSx Polycrystalline Alloys.

Some transition-metal dichalcogenides have been actively studied recently owing to their potential for use as thermoelectric materials due to their superior electronic transport properties. Iron-based chalcogenides, FeTe2, FeSe2 and FeS2, are narrow bandgap (~1 eV) semiconductors that could be considered as cost-effective thermoelectric materials. Herein, the thermoelectric and electrical transport properties FeSe2-FeS2 system are investigated. A series of polycrystalline samples of the nominal composition of FeSe2-xSx (x = 0, 0.2, 0.4, 0.6, and 0.8) samples are synthesized by a conventional solid-state reaction. A single orthorhombic phase of FeSe2 is successfully synthesized for x = 0, 0.2, and 0.4, while secondary phases (Fe7S8 or FeS2) are identified as well for x = 0.6 and 0.8. The lattice parameters gradually decrease gradually with S content increase to x = 0.6, suggesting that S atoms are successfully substituted at the Se sites in the FeSe2 orthorhombic crystal structure. The electrical conductivity increases gradually with the S content, whereas the positive Seebeck coefficient decreases gradually with the S content at 300 K. The maximum power factor of 0.55 mW/mK2 at 600 K was seen for x = 0.2, which is a 10% increase compared to the pristine FeSe2 sample. Interestingly, the total thermal conductivity at 300 K of 7.96 W/mK (x = 0) decreases gradually and significantly to 2.58 W/mK for x = 0.6 owing to the point-defect phonon scattering by the partial substitution of S atoms at the Se site. As a result, a maximum thermoelectric figure of merit of 0.079 is obtained for the FeSe1.8S0.2 (x = 0.2) sample at 600 K, which is 18% higher than that of the pristine FeSe2 sample.

Superior Mechanical Properties of GaAs Driven by Lattice NanotwinningSupported by the National Key Research and Development Program of China (Grant No. 2018YFA0703400), the National Natural Science Foundation of China (Grant Nos. 11704044 and 11974134), the Jilin Province Outstanding Young Talents Project (Grant No. 20190103040JH), and the China Postdoctoral Science Foundation (Grant No. 2018M631870).

Gallium arsenide (GaAs), a typical covalent semiconductor, is widely used in the electronic industry, owing to its superior electron transport properties. However, its brittle nature is a drawback that has so far significantly limited its application. An exploration of the structural deformation modes of GaAs under large strain at the atomic level, and the formulation of strategies to enhance its mechanical properties is highly desirable. The stress-strain relations and deformation modes of single-crystal and nanotwinned GaAs under various loading conditions are systematically investigated, using first-principles calculations. Our results show that the ideal strengths of nanotwinned GaAs are 14% and 15% higher than that of single-crystal GaAs under pure and indentation shear strains, respectively, without producing a significantly negative effect in terms of its electronic performance. The enhancement in strength stems from the rearrangement of directional covalent bonds at the twin boundary. Our results offer a fundamental understanding of the mechanical properties of single crystal GaAs, and provide insights into the strengthening mechanism of nanotwinned GaAs, which could prove highly beneficial in terms of developing reliable electronic devices.

Bidimensional H‐Bond Network Promotes Structural Order and Electron Transport in BPyMPMs Molecular Semiconductor

AbstractThe presence of a hydrogen bond (H‐Bond) network has been proved to impact significantly the efficiency of organic light‐emitting diode (OLED) devices by promoting molecular orientation and structural anisotropy in thin films. The design of specific compounds to control H‐Bond network formation in an amorphous material, and hence to improve OLED performances, is needed. A successful example is given by the bi‐pyridyl‐based family n‐type of organic semiconductors named BPyMPM. The experimental evidences demonstrate a surprisingly higher electron mobility in thin film composed of 4,6‐bis(3,5‐di(pyridine‐4‐yl)phenyl)‐2‐methylpyrimidine (B4PyMPM (B4)), which is almost two order of magnitude higher than mobility measured for very similar member of the family, 4,6‐bis(3,5‐di(pyridine‐2‐yl)phenyl)‐2‐methylpyrimidine (B2PyMPM (B2)). Herein, a comprehensive computational study is presented, wherein classical and ab initio methods are combined, to investigate the 2D H‐Bond network in B4 and B2 thin films. The results indicate that B4 forms a larger number of intermolecular C‐H···N H‐Bonds that promote a higher orientational and positional order in B4 films, and superior electron transport properties.

Spatial configuration engineering of perylenediimide-based non-fullerene electron transport materials for efficient inverted perovskite solar cells

Abstract Due to their excellent photoelectron chemical properties and suitable energy level alignment with perovskite, perylene diimide (PDI) derivatives are competitive non-fullerene electron transport material (ETM) candidates for perovskite solar cells (PSCs). However, the conjugated rigid plane structure of PDI units result in PDI-based ETMs tending to form large aggregates, limiting their application and photovoltaic performance. In this study, to restrict aggregation and further enhance the photovoltaic performance of PDI-type ETMs, two PDI-based ETMs, termed PDO-PDI2 (dimer) and PDO-PDI3 (trimer), were constructed by introducing a phenothiazine 5,5-dioxide (PDO) core building block. The research manifests that the optoelectronic properties and film formation property of PDO-PDI2 and PDO-PDI3 were deeply affected by the molecular spatial configuration. Applied in PSCs, PDO-PDI3 with three-dimensional spiral molecular structure, exhibits superior electron extraction and transport properties, further achieving the best PCE of 18.72% and maintaining 93% of its initial efficiency after a 720-h aging test under ambient conditions.

Potassium salt promoted regioselective three-component coupling synthesis of 1,4-asymmetrical [60]fullerene bisadducts with superior electron transport properties.

An efficient one-pot three-component domino coupling reaction of phenols, C60, and bromoalkanes was developed, resulting in the highly regioselective synthesis of 1,4-asymmetrical C60 bisadducts. The reaction utilizes KOtBu as a promoter and likely proceeds by an oxyanion/carbanion rearrangement/nucleophilic addition cascade. This new methodology is particularly effective for the synthesis of 1,4-asymmetrical C60 electron transport materials. Its utility is demonstrated by the synthesis of a new efficient 1,4-C60 ETM, which possesses better performance, easier synthesis, and a lower cost compared with the commercially available PCBM.

Superior Thermoelectric Performance of Ordered Double Transition Metal MXenes: Cr2TiC2T2 (T = -OH or -F).

Using SCAN-rVV10+U, we show Cr2TiC2 and Cr2TiC2T2 (T = -F and -OH) MXenes are moderate band gap semiconductors mostly in the antiferromagnetic state. All investigated MXene structures show large Seebeck coefficients (>400 μV/K), especially Cr2TiC2 (>800 μV/K) and Cr2TiC2F2 (>700 μV/K). The hole relaxation time of p-type Cr2TiC2(OH)2 is found to be ∼8 ps, ensuring its superior electron transport properties in comparison to other investigated MXenes. It is also discovered that the surface functionalization could decrease the phonon thermal conduction and that Cr2TiC2(OH)2 has the smallest lattice thermal conductivity (∼6.5 W/m·K) and the largest electron thermal conduction (>50 W/m·K with n = 1019 cm-3). We predict the ZT value of p-type Cr2TiC2(OH)2 can reach 3.0 at 600 K with the maximum thermoelectric conversion efficiency of 20%. Overall, the thermoelectric property of Cr-based ordered double transition metal MXenes is far superior to that of any known two-dimensional structures in the MXene family.

(Invited) Two-Dimensional Layered Materials Toward Phase-Engineered Hybrid Films

2D materials have attracted much attention because of frontier electronic materials due to its superior electronic transport properties and mechanical flexibility in the future, making it a potential material for high performance and wearable electronics. Graphene is a typical 2D materials with high carrier mobility; however, it still cannot be applied in transistor due to the lack of bandgap. A new type of 2D semiconducting materials called transition metal dichalcogenides (TMDCs), which are layered structure with the strong in-plane bonding and weak out-of-plane interactions similar to graphite, have been intensively studied. Recent studies have predicted exceptional physical properties upon reduced dimensionality attracting lots of attention due to the versatile physical chemical behaviors. Nevertheless, the synthesis and the study of the fundamental physical properties of TMDs are still in early stages. The lack of a large-area and reliable synthesis method restrict exploring all the potential applications of the TMDs. Chemical vapor deposition (CVD) is a traditional approach for the growth of TMDs; nevertheless, the high growth temperature is a major drawback for its to be applied in flexible electronics. In this talk, an inductively coupled plasma (ICP) was used to synthesize Transition Metal Dichalcogenides (TMDs) through a plasma-assisted selenization process of metal oxide (MOx) at a low temperature, as low as 250 °C. Compared to other CVD processes the use of ICP facilitates the decomposition of the precursors at lower temperatures; therefore, the temperature required for the formation of TMDs can be drastically reduced. WSe2 was chosen as a model material system due to its technological importance as a p-type inorganic semiconductor with an excellent hole mobility. Large-area synthesis of WSe2 on polyimide (30 x 40 cm2) flexible substrates and 8-inch silicon wafers with good uniformity was demonstrated at the formation temperature of 250 °C as confirmed by Raman and X-ray Photoelectron (XPS) spectroscopy. Furthermore, by controlling different H2/N2 ratios, hybrid WOx/WSe2 films can be formed at the formation temperature of 250 ºC as shown by TEM and confirmed by XPS. The applications including (1) water splitting, (2) gas sensors and (3) photodetectors will be reported.

Syngas production by electrocatalytic reduction of CO2 using Ag-decorated TiO2 nanotubes

Huge efforts have been done in the last years on electrochemical and photoelectrochemical reduction of CO2 to offer a sustainable route to recycle CO2. A promising route is to electrochemically reduce CO2 into CO which, by combination with hydrogen, can be used as a feedstock to different added-value products or fuels. Herein, perpendicular oriented TiO2 nanotubes (NTs) on the electrode plate were grown by anodic oxidation of titanium substrate and then decorated by a low loading of silver nanoparticles deposited by sputtering (i.e. Ag/TiO2 NTs). Due to their quasi one-dimensional arrangement, TiO2 NTs are able to provide higher surface area for Ag adhesion and superior electron transport properties than other Ti substrates (e.g. Ti foil and TiO2 nanoparticles), as confirmed by electrochemical (CV, EIS, electrochemical active surface area) and chemical/morphological analysis (FESEM, TEM, EDS). These characteristics together with the role of the TiO2 NTs to enhance the stability of CO2·- intermediate formed due to titania redox couple (TiIV/TiIII) lead to an improvement of the CO production in the Ag/TiO2 NTs electrodes. Particular attention has been devoted to reduce the loading of noble metal in the electrode(14.5 %w/%w) and to increase the catalysts active surface area in order to decrease the required overpotential.