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A novel method using intense pulsed light (IPL) for the metal nano-island formation on carbon nanotube (CNT) was introduced. The IPL-induced photothermal dewetting process improved platinum (Pt) catalyst utilization by transforming nano-islands from Pt film on CNT and increasing the surface area for the subsequent sputtering. The irradiation of high intensity of light on the Pt film causes surface-energy-driven diffusion of Pt atoms and forms the array of nano-islands on CNT. The thickness of Pt film can change the size of nano-islands. Cyclic voltammetry showed a dramatically improved glucose oxidation at the IPL morphology modified Pt-CNT electrode compared to the Pt sputtered CNT electrode without IPL irradiation. The power densities of glucose/air biofuel cell based on the morphology modified Pt-CNT electrode and the as-sputtered Pt-CNT electrode were 0.768 microW/cm(2) and 0.178 microW/cm(2), respectively. The biofuel cell based on morphology modified Pt-CNT electrode showed highly stable output in long-term performance. The power density dropped 14.1% in 30 days. Efforts are underway to improve the interface transfer to achieve higher potential and current output., ((c) 2009 Elsevier B.V. All rights reserved.)

Carboxylated single-walled carbon nanotubes (SWCNT) chemically assembled on gold substrate was employed as netlike electrode to investigate the charge-transfer process and electrode process kinetics using uric acid as an example. The electrochemical behavior of uric acid in carboxylated SWCNT system was investigated using cyclic voltammetry, chronoamperometry, and single potential time-based techniques. The properties of raw SWCNT electrode were also studied for comparison purpose. Uric acid has better electrochemical behavior whereas ascorbic acid has no effective reaction on the carboxylated SWCNT electrode. Cyclic voltammograms indicate that the assembled carboxylated SWCNT increases more active sites on electrode surface and slows down the electron transfer between the gold electrode and uric acid in solution. The charge-transfer coefficient (alpha) for uric acid and the rate constant (k) for the catalytic reaction were calculated as 0.52 and 0.43 s(-1), respectively. The diffusion coefficient of 0.5 mM uric acid was 7.5 x 10(-6) cm2 x s(-1). The results indicate that electrode process in the carboxylated SWCNT electrode system is governed by the surface adsorption-controlled electrochemical process.

Additively printed circuits provide advantages in reduced waste, rapid prototyping, and versatile flexible substrate choices relative to conventional circuit printing. Copper (Cu) based inks along with intense pulsed light (IPL) sintering can be used in additive circuit printing. However, IPL sintered Cu typically suffer from poor solderability due to high roughness and porosity. To address this, hybrid Cu ink which consists of Cu precursor/nanoparticle was formulated to seed Cu species and fill voids in the sintered structure. Nickel (Ni) electroplating was utilized to further improve surface solderability. Simulations were performed at various electroplating conditions and Cu cathode surface roughness using the multi-physics finite element method. By utilizing a mask during IPL sintering, conductivity was induced in exposed regions; this was utilized to achieve selective Ni-electroplating. Surface morphology and cross section analysis of the electrodes were observed through scanning electron microscopy and a 3D optical profilometer. Energy dispersive X-ray spectroscopy analysis was conducted to investigate changes in surface compositions. ASTM D3359 adhesion testing was performed to examine the adhesion between the electrode and substrate. Solder-electrode shear tests were investigated with a tensile tester to observe the shear strength between solder and electrodes. By utilizing Cu precursors and novel multifaceted approach of IPL sintering, a robust and solderable Ni electroplated conductive Cu printed electrode was achieved. [ABSTRACT FROM AUTHOR]

In this study, we developed a new way to increase the efficiency of dye-sensitized solar cells by using TiO2/silver/carbon nanotube composites as the working electrode. Silver nanoparticles and multi-walled carbon nanotubes were mixed with TiO2 nanoparticles and used as working electrodes in a dye-sensitized solar cell. The effect of the silver nanoparticles and multi-walled carbon nanotubes on the efficiency of the dye-sensitized solar cell was studied as function of their volume fractions using several microscopic and spectroscopic characterization techniques such as scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultra-violet-vis and electrochemical impedance spectroscopy. It was found that the silver nanoparticles could induce surface plasmonic phenomena, where the light absorption was enhanced in the ultra-violet wavelength range. Additionally, the carbon nanotubes could increase the electron mobility in the working electrode due to their high surface-to-volume ratio and superior electrical conductivity. The efficiency of the silver/carbon nanotube/TiO2 nanocomposite working electrode was compared with that of a conventional TiO2 working electrode under one-sun illumination (100 mWcm–2, AM 1.5 G). The TiO2/Ag/carbon nanotube nanocomposite working electrode had a two-fold higher efficiency (3.76%) than the conventional pure TiO2 working electrode (1.88%). [ABSTRACT FROM PUBLISHER]

Abstract: Copper nano-ink with a drop-on-demand (DOD) piezoelectric inkjet printing method was introduced. The printed electrodes were thermally sintered to ensure high-quality electrical and mechanical performances. To check the reliability of the printed electrodes on a polymer layer, resistance changes were measured under static loading. The electrodes with various widths and thicknesses were used to find the optimal dimensions. A multifunctional composite laminate which can harvest and store a solar energy was fabricated using printed electrodes. An amorphous silicon solar cell and a thin film solid state lithium-ion battery were adhesively joined and electrically connected to a thin flexible printed circuit board (PCB). Then, the passive components such as resistor and diode were electrically connected to the printed circuit board by silver pasting. The integrated PCB was co-cured with a carbon/epoxy composite laminate by the vacuum bag molding process in an autoclave. The structural and functional performance of the final energy harvesting/storage composite laminate was tested under mechanical loading. [Copyright &y& Elsevier]

In this work, the hybrid copper inks with precursor and nanoparticles were fabricated and sintered via flash light irradiation to achieve highly conductive electrode pattern with low porosity. The hybrid copper ink was made of copper nanoparticles and various copper precursors (e.g., copper(II) chloride, copper(II) nitrate trihydrate, copper(II) sulfate pentahydrate and copper(II) trifluoroacetylacetonate). The printed hybrid copper inks were sintered at room temperature and under ambient conditions using an in-house flash light sintering system. The effects of copper precursor weight fraction and the flash light irradiation conditions (light energy and pulse duration) were investigated. Surfaces of the sintered hybrid copper patterns were analyzed using a scanning electron microscope. Also, spectroscopic characterization techniques such as Fourier transform infrared spectroscopy and X-ray diffraction were used to investigate the crystal phases of the flash light sintered copper precursors. High conductivity hybrid copper patterns (27.3 μΩ cm), which is comparable to the resistivity of bulk copper (1.68 μΩ cm) were obtained through flash light sintering at room temperature and under ambient conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Scalable Flash White Light (FWL) sintering of copper nanoparticles on silicon wafer is used to create highly conductive electrodes for crystalline silicon solar cells. After 1 s of FWL sintering, the Cu electrode has high electrical conductivity with lower cost, and no thermal damage, as compared to the state-of-the-art. Highlights • A new way to fabricate Cu electrodes using flash white light is demonstrated. • Flash white light sintering process is dramatically simple and high speed process. • Multi-pulsed FWL sintering method was developed for crystalline Si solar cells. • Artificial oxidation treatment improves the FWL sintering of Cu NPs on Si wafer. • Highly conductive Cu films were successfully produced under ambient conditions. Abstract In this work, ultra-high speed flash white light (FWL) sintering method of copper nanoparticle pastes on silicon wafer substrate, was developed to produce highly conductive and low-cost copper electrodes for crystalline silicon solar cells. FWL sintering of copper nanoparticles on silicon wafer substrate has been regarded to be very difficult, due to its high thermal conductivity (k) compared with that of polymer (PI and PET) substrates. To overcome this limitation, we applied multiple pulsed FWL to sinter copper nanoparticles (Cu NPs) printed on silicon wafer. Furthermore, bimodal Cu NPs with different size were also applied to enhance the packing density of Cu films for highly conductive Cu electrodes. Finally, this work demonstrated that Cu NP-pastes are successfully sintered on crystalline silicon wafer substrate by multiple pulsed FWL irradiations. [ABSTRACT FROM AUTHOR]

Highlights • CuS/WS 2 heterostructure was synthesized via a sputtering-CVD process for counter electrode in DSSCs. • It showed low charge transfer resistance, good electrocatalytic activity and strong electrochemical stability. • The constructed DSSC using CuS/WS 2 CE achieved high power conversion efficiency of 8.21% • That value is comparable to that of Pt CE (8.74%) and higher than that of pristine WS 2 , MoS 2 , and CuS CEs. • CuS/WS 2 CE shows promising counter electrode for DSSCs. Abstract In this work, we demonstrated CuS/WS 2 and CuS/MoS 2 heterostructures via a sputtering-CVD process for dye-sensitized solar cells (DSSCs) as a counter electrode (CE) to replace the currently preferred expensive platinum (Pt). The cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel curve studies revealed that the unique CuS/WS 2 and CuS/MoS 2 heterostructures were beneficial in achieving high electrocatalytic activity, low charge-transfer resistance at the CE/electrolyte interface, and fast reaction kinetics for the reduction of triiodide to iodide at the CE. The constructed DSSCs using these CuS/WS 2 and CuS/MoS 2 CEs exhibited high-power conversion efficiencies (PCEs) of 8.21% and 7.12%, respectively, which are comparable to conventional Pt CE (8.74%) and pristine WS 2 , MoS 2 , and CuS CEs (6.0%, 6.3% and 6.4%). This novel sulfur based heterostructure opens up opportunities for a variety of optoelectronic and photoelectrochemical applications. [ABSTRACT FROM AUTHOR]

The counter electrode has a great influence on the performance of dye-sensitized solar cells (DSSCs). In this work, efforts have been made to develop a platinum (Pt)-free, low-cost, copper sulfide (CuS) counter electrode for application in DSSCs. CuS thin film was successfully grown on a conducting and non-conducting substrate using a low temperature, one pot, solution-process method. The as-synthesized CuS thin film was utilized in the DSSCs as a counter electrode (CE). The CE demonstrated good electrocatalytic properties and a photoconversion efficiency (PCE) of 5.03% when used in DSSCs. It was also comparable with devices made using platinum counter electrodes. Synthesized CuS thin film with excellent electrocatalytic properties could serve as an alternative counter electrode in DSSC fabrication. [ABSTRACT FROM AUTHOR]

Transparent conducting electrodes (TCEs) are fabricated through the flash light sintering of reverse-offset printed Ag mesh patterns. Interestingly, the narrower printing lines require a higher flash light energy to obtain an equivalent sheet resistance even if the same Ag nanoparticle ink is used. The microstructural development of sintered Ag nanoparticles is also retarded with the decrease of line width after the same flash light sintering. The temperature calculation in the Ag mesh patterns clearly reveals that heat dissipation is affected by the print dimension. To improve the performance of Ag mesh TCEs with 3 μm wide lines, a preheating step comprised of multi-pulses is inserted before a main flash light sintering. The multi-pulsed flash light sintering is effective in decreasing the sample temperature and in removing the substrate damages or microstructural defects. As a result, the flash light-sintered Ag mesh TCEs shows a sheet resistance of 27 Ω/□ and an optical transmittance of 84.7% including an optical transmittance of substrate. [ABSTRACT FROM AUTHOR]

The electrical-resistance-change method (ERCM) is a potential smart-sensing technique for carbon-fiber-reinforced plastic (CFRP) structures. However, a practical way to fabricate electrodes on CFRP structures, such as ink-jet printing with metal nano-inks, is necessary to reduce the time required for the process. As metal nano-inks can be sintered in a few milliseconds under ambient conditions using white-flash-light irradiation from a xenon lamp, the parameters of flash-light sintering such as light energy, duration, and number of pulses were investigated. The light intensity, which is the light energy divided by duration, was found to be an indicator of whether low electrical resistance was attained along with strong adhesion to the CFRP plate. The contact resistance between the electrode and CFRP plate was also examined in a tensile test to confirm the durability. The electrode sintered by flash light with the properly selected parameters exhibited high quality and strain monitoring capability. [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical behavior of needle-like and forest-like single-walled carbon nanotube (SWCNT) electrodes, wet-chemically assembled on a gold substrate, were investigated by cyclic voltammetry and single potential time-based techniques. The results indicate that a SWCNT electrode system exhibits quasi-reversible behavior, and SWCNT electrodes exhibit better electrochemical behavior than bare gold electrodes. A forest-like SWCNT electrode possesses the best electrochemical behavior. This is explained using Randle’s equivalent circuit unit during the electron-transfer process between the redox centre and the SWCNT electrode surface, and an alternative electron-transfer mechanism was suggested for the observed electrochemical properties. [Copyright &y& Elsevier]

In typical dye-sensitized solar cells, platinum metal-based counter electrode is employed to collect electrons from the external circuit and catalyze the triiodide (I 3 ⁻) reduction in the electrolyte. However, due to the high cost of platinum, development of inexpensive material based counter electrodes is highly desirable to lower the cost of production of the devices. Herein, we report a facile strategy to deposit a cobalt-nickel sulfide nanostructured thin film showing promising electrocatalytic characteristics, as a low-cost counter electrode material. A simple one-step solution-based fabrication method for the binder-free cobalt-nickel sulfide counter electrode at low-temperature is one of the key features of this work. The as-deposited cobalt-nickel sulfide film is highly crystalline even without thermal treatment. The results demonstrate that the as-obtained cobalt-nickel sulfide thin film on a conductive substrate can be employed as a counter electrode directly in a dye-sensitized solar cell. Cyclic voltammetry, Tafel plot and electrochemical impedance spectroscopy show that the as-synthesized cobalt-nickel sulfide counter electrode exhibits an excellent electrocatalytic property competing with the state-of-the-art platinum counter electrode. As a result, the dye-sensitized solar cell based on the cobalt-nickel sulfide counter electrode yields the best power conversion efficiency of 8.86%, which closely matches the performance of the dye-sensitized solar cell based on a platinum counter electrode (9.08%). The excellent electrocatalytic property obtained from the low cost and simple synthesis process could render the cobalt-nickel sulfide nanostructure standing out as a competitive alternative to the expensive platinum counter electrode. As such, this work overlays a path for the rational design of inexpensive, and so far achieved highly-efficient cobalt-nickel sulfide counter electrode for the advanced energy applications. Cobalt-nickel sulfide (CoNi 2 S 4) can be grown on fluorine-doped tin oxide substrate via a simple facial synthesis method in an ethanol solvent, and it can be employed as a counter electrode directly in a dye-sensitized solar cell. Dye-sensitized solar cell based on the Cobalt-nickel sulfide counter electrode showed a high power conversion efficiency of 8.86% which is comparable to that of the platinum counter electrode showing the photoconversion efficiency of 9.08%. Image 1 • A simple ethanol solvent-based process is presented for CoNi 2 S 4 film formation. • Film formation is performed without using complex and pH regulating agent at 80 °C. • The as-deposited films are highly crystalline even without thermal treatment. • Films can be deposited on conducting as well as non-conducting substrates. • CoNi 2 S 4 showed an efficiency of 8.86%-competing to Platinum reference (9.06%). [ABSTRACT FROM AUTHOR]