Advanced humidity sensing properties of CuO ceramics.

This research explores the capacitive humidity sensing properties of CuO ceramic, selected for its simplicity as an oxide and ease of fabrication, in addition to its remarkable dielectric properties. The CuO sample was fabricated by sintering at 980 °C for 5 h. A microstructure with a relative density of 88.9% was obtained. X-ray diffraction confirmed the formation of a pure CuO phase. Broadband dielectric spectroscopy revealed that the observed giant dielectric properties at room temperature (RT) were attributed to extrinsic effects, including the internal barrier layer capacitor and sample-electrode contact effects. A key focus of this study was to examine the giant dielectric properties of CuO ceramic as a function of relative humidity (RH) at RT and frequencies of 102 and 103 Hz. It was observed that the capacitance of CuO continuously increased with rising RH levels, ranging from 30 to 95%. Notably, the maximum hysteresis errors were constrained to 2.3 and 3.3% at 102 and 103 Hz, respectively. Additionally, the CuO ceramic demonstrated very fast response and recovery times, approximately 2.8 and 0.95 min, respectively. The repeatability of the humidity response of the capacitance was also established. Overall, this research highlights the high potential of CuO as a giant dielectric material for application in humidity sensors.

Photoinduced charge generation of nanostructured carbon derived from human hair biowaste for performance enhancement in polyvinylidene fluoride based triboelectric nanogenerator.

Carbon nanostructures derived from human hair biowaste are incorporated into polyvinylidene fluoride (PVDF) polymer to enhance the energy conversion performance of a triboelectric nanogenerator (TENG). The PVDF filled with activated carbon nanomaterial from human hair (AC-HH) exhibits improved surface charge density and photoinduced charge generation. These remarkable properties are attributed to the presence of graphene-like nanostructures in AC-HH, contributing to the augmented performance of PVDF@AC-HH TENG. The correlation of surface morphologies, surface charge potential, charge capacitance properties, and TENG electrical output of the PVDF composites at various AC-HH loading is studied and discussed. Applications of the PVDF@AC-HH TENG as a power source for micro/nanoelectronics and a movement sensor for detecting finger gestures are also demonstrated. The photoresponse property of the fabricated TENG is demonstrated and analyzed in-depth. The analysis indicates that the photoinduced charge carriers originate from the conductive reduced graphene oxide (rGO), contributing to the enhanced surface charge density of the PVDF composite film. This research introduces a novel approach to enhancing TENG performance through the utilization of carbon nanostructures derived from human biowaste. The findings of this work are crucial for the development of innovative energy-harvesting technology with multifunctionality, including power generation, motion detection, and photoresponse capabilities.

Thermally Deposited Palladium-Tungsten Carbide and Platinum-Tungsten Carbide Counter Electrodes for a High Performance Dye-Sensitized Solar Cell Based on Organic T-/T2 Electrolyte.

Tungsten carbide (WC) particles (~1 µm) were dispersed in DI water and dropped onto conductive glass. The resulting WC films were used as dye-sensitized solar cell (DSSC) counter electrodes. The performance of the WC DSSC based on the organic thiolate/disulfide (T-/T2) electrolyte was ~0.78%. The cell efficiency was greatly improved after decorating palladium (Pd) or platinum (Pt) nanoparticles on WC particles with a promising efficiency of ~2.15% for Pd-WC DSSC and ~4.62% for Pt-WC DSSC. The efficiency improvement of the composited (Pd-WC and Pt-WC) cells is attributed to co-functioning catalysts, the large electrode interfacial area and a low charge-transfer resistance at the electrolyte/counter electrode interface.

A dye sensitized solar cell using natural counter electrode and natural dye derived from mangosteen peel waste.

Mangosteen peel is an inedible portion of a fruit. We are interested in using these residues as components of a dye sensitized solar cell (DSSC). Carbonized mangosteen peel was used with mangosteen peel dye as a natural counter electrode and a natural photosensitizer, respectively. A distinctive mesoporous honeycomb-like carbon structure with a rough nanoscale surface was found in carbonized mangosteen peels. The efficiency of a dye sensitized solar cell using carbonized mangosteen peel was compared to that of DSSCs with Pt and PEDOT-PSS counter electrodes. The highest solar conversion efficiency (2.63%) was obtained when using carbonized mangosteen peel and an organic disulfide/thiolate (T2/T(-)) electrolyte.

Quasi-solid-state dye-sensitized solar cells based on TiO2/NiO core-shell nanocomposites.

The core-shell nanocomposites of titanium dioxide (TiO2) and nickel oxide (NiO) used as modified photoelectrode materials in a quasi-solid-state dye-sensitized solar cell (quasi-DSSC) were synthesized using TiO2 P-25 and a nickel acetate precursor, via ball milling. The as-obtained intermediate products were annealed at 350, 450, and 550 degrees C. The structural properties of the NiO/TiO2 nanocomposites were well characterized via X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The results imply that NiO-shell-coated TiO2 nanoparticles can be obtained with the assistance of sufficient thermal energy in the system. The crystallite size of the composite increased as the annealing temperature increased. Among all the prepared conditions, the composite with 0.1 wt% NiO exhibited the best performance, with an optimized solar-energy conversion efficiency of 2.29% and with a short-circuit current density of 7.21 mA/cm2. The significant enhancement of the device's current density may be associated with the charge recombination suppression by the NiO shell, which acted as a potential barrier in the composite. The decrease in the recombination of the photo-injected electrons, and the increase in the number of electrons tunneling through the NiO layer at the interface, may have resulted from the presence of a NiO layer on the TiO2 nanoparticles.

Solid-state dye-sensitized solar cells fabricated by coupling photoelectrochemically deposited poly(3,4-ethylenedioxythiophene) (PEDOT) with silver-paint on cathode.

A PEDOT-based dye-sensitized solar cell (DSC) is successfully improved by coupling photoelectrochemically deposited PEDOT layer with an Ag paste-paint on the cathode. With a 9.3 µm thick mesoscopic nanocrystalline TiO(2) film, a maximum cell performance of 3.2% with relatively high V(oc) of around 780 mV is achieved.