Rapid Fabrication of Oxygen Defective α-Fe2O3(110) for Enhanced Photoelectrochemical Activities

This is the author accepted manuscript.Defect engineering is increasingly recognized as a viable strategy for boosting the performance of photoelectrochemical (PEC) water splitting by metal oxide-based photoelectrodes. However, previously developed methods for generating point defect associated with oxygen vacancies is rather time-consuming. Herein, high density oxygen deficient α-Fe2O3 with dominant (110) crystal plane is developed in very short timescale of 10 minutes by employing aerosol-assisted chemical vapor deposition and pure nitrogen as gas carrier. The oxygen defective film exhibits almost 8 times higher photocurrent density compared to hematite photoanode with low concentration of oxygen vacancies which is prepared in purified air. The existence of oxygen vacancies improves light absorption ability, accelerates charge transport in the bulk of film, and promotes charge separation at electrolyte/semiconductor interface. DFT simulations verify that oxygen defective hematite has a narrow band gap, electron-hole trapped centre, and strong adsorption energy of water molecules compared to that of pristine hematite. This strategy might bring PEC technology another step further towards large-scale fabrication for future commercialization.Universiti Kebangsaan Malaysi

The role of tin species in doped iron (III) oxide for photocatalytic degradation of methyl orange dye under UV light

Iron (III) oxide, a stable semiconductor with versatile applications, was synthesized alongside Sn-doped Fe2O3 (Sn–Fe2O3) using the sol-gel technique. Characterization via X-ray diffraction, field-emission scanning electron microscopy, and UV–visible spectroscopy confirmed the presence of α- and γ-Fe2O3 phases in the synthesized powders. Incorporation of the dopant reduced the initial band gap energy of Fe2O3 (2.2 eV) by approximately 0.1 eV. To evaluate photocatalytic performance, Fe2O3 and Sn–Fe2O3 were tested for decolorization efficiency of a methyl orange solution. Results revealed the 5 wt% Sn-doped catalyst as optimal, achieving complete degradation of methyl orange within 120 min under simulated solar light. The addition of small amounts of Sn effectively reduced the Fe2O3 band gap and significantly enhanced photocatalytic performance. Investigation of pH and dye concentration impact on photocatalytic degradation revealed superior activity under acidic conditions compared to alkaline. Furthermore, maintaining a moderate concentration of methyl orange (10 ppm) ensured optimum photocatalytic activity

Analysis of breathing patterns from thermal images using an automated segmentation method

Breathing is one of the important vital signs in diagnosing and monitoring for patients' treatment and disease. Few modalities have been used to evaluate breathing activity such as respiratory belt, thermistor and capacitive sensor. However, these requires external attachments such as electrode or sensor which might be inconvenience over long period of time. Hence, we proposed the use of thermography as a contactless monitoring device. In this study, inspiration time and expiration time of three different breathing patterns such as normal, prolonged and rapid breathing patterns were measured by using the thermography. Thermal images obtained from the subjects were processed and analysed by using an automated segmentation method which integrate the knowledge of edge-based and region-based segmentation methods into the algorithm developed. The algorithm developed in this study has shown that the tracker was able to segment the region of interest of the thermal images automatically and it provides a more accurate and stable results than manual calculation method. Thus, three different types of breathing patterns could be identified based on the inspiration time to expiration time ratio. Results shows that there was less than 5% of relative error which suggest the benefit of this algorithm

Electrodeposition of BiVO<inf>4</inf> with needle-like flower architecture for high performance photoelectrochemical splitting of water

Photoelectrochemical (PEC) water splitting is a green and sustainable approach capable of driving mass hydrogen production in the future. To realize this vision, development of a well-performing photoelectrode is highly demanded. In this comprehensive study, electrodeposition technique was applied for fabricating BiVO4 films by regulating the deposition time from 1 min until 9 min. Interestingly, the morphology, crystallinity, chemical structure, and optical properties of BiVO4 films depend strongly on the deposition time. It is found that BiVO4 layer deposited for 7 min with a cross-section thickness of around 321.1–326.5 nm showed the optimum performance, whereby the photocurrent reached up to ~0.32 mA/cm−2 at 1.23 V vs. RHE. The deposited BiVO4 represents tiny and long petals, similar to “needle” nanostructures, which is embedded closely into compact agglomerates. Such morphology enables the BiVO4 films to perform efficiently as photoanode in PEC cells. Besides, high crystallinity is detected from the sharp peaks of XRD and Raman analysis, as well as good light absorption capability that are the main contributors to the enhancement of PEC performance. In addition to the facile fabrication offered by electrodeposition method, the non-toxic attributes and the impressive PEC performance of the optimum BiVO4 layer could serve as an interesting option for other applications such as gas sensors, solar cells, degradation of pollutants and photocatalytic water splitting

WTa37O95.487 Nanocatalyst for Pollutant Degradation

This is the author accepted manuscript. The final version is available from the American Chemical Society via the DOI in this recordData Availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.The release of toxic industrial effluents has created serious impacts on human health and the aquatic ecosystem. WTa37O95.487 is a wide-band gap material that was reported in 1971, but no one has investigated its photocatalytic properties due to its wide band gap and unique crystal structure. Herein, we carried out detailed experimental and density functional theory (DFT) simulations of WTa37O95.487 nanocatalysts. The influence of temperature and light intensity on their crystallography, morphology, optical, and photocatalytic properties was studied. The powder obtained at 150 °C (WT-1) exhibited higher photocatalytic activity of 99% of methylene blue dye degradation within 30 min with a pseudo-first-order kinetics constant of 0.0643 min–1. DFT simulations revealed a good correlation between theory and experiment of electronic properties of WTa37O95.487, which consequently validate the catalytic performance of the catalyst. The WTa37O95.487 nanocatalyst is proposed as a novel and effective photocatalyst for treating dye effluents of wastewater.National University of MalaysiaCenter for Research and Instrumentation (CRIM)Engineering and Physical Sciences Research Council (EPSRC

High-humidity processed perovskite solar cells

Perovskite solar cells (PSCs) are considered the next-in-line technology in the solar industry. This technology can reduce the cost of solar energy to an unprecedented level given their remarkably high efficiency and ease of manufacturing. Hitherto, many studies have preferred well-regulated inert conditions or a low-humidity atmosphere (relative humidity < 30%) for fabricating highly efficient PSCs to avoid the adverse impact of humidity on a perovskite film. This is because humidity is the main reason for perovskite instability and can alter the film growth kinetics during the fabrication process, thereby ultimately affecting the morphology of the grown film and the device performance. The requirement for an inert or low-humidity environment can increase the capital costs of setting up the fabrication facilities and hamper the large-scale production of PSCs. Therefore, efforts have been devoted to preparing PSC devices in a high-humidity environment to comprehend perovskite crystal growth kinetics and improve the morphological properties and stability of the perovskite film. This review highlights the modifications implemented towards (1) perovskite materials, (2) charge-selective layers, and (3) deposition protocols by spin-coating, to adapt a high-humidity atmosphere (RH ≥ 30%) for developing efficient PSCs. The progress of scalable processing methods such as blade-coating, inkjet printing, slot-die coating, and spray-coating, and the translation of spin-coating-modified protocols into these methods are also discussed. Finally, this review provides the remaining challenges to realizing the high-humidity fabrication of PSCs for commercialization

Boosting photocatalytic activities of BiVO<inf>4</inf> by creation of g-C<inf>3</inf>N<inf>4</inf>/ZnO@BiVO<inf>4</inf> Heterojunction

© 2020 Elsevier Ltd BiVO4 has attracted great attention as a semiconductor for Photoelectrochemical (PEC) water splitting because of its low cost, good stability, and suitable band gap of 2.4 eV. In this research, the contribution of g-C3N4@ZnO on BiVO4 photoelectrochemical performance, light absorption, charge transportation, and morphology were investigated. Incorporation of g-C3N4/ZnO as underlying layer in heterojunction with BiVO4 boosted the photocurrent from ∼ 0.21 mA cm−2 for bare BiVO4 to 0.65 mA cm−2 for g-C3N4@ZnO/BiVO4 heterojunction composite structure at 1.23 V versus Ag/AgCl. The C and N elements derived from g-C3N4 on ZnO resulted in a tenacious interactions, lowered charge transfer resistance and increased light absorption of BiVO4. The high photoelectrochemical performance, together with good electrochemical impedance spectroscopy parameters and stability reveals g-C3N4/ZnO composite to be a suitable candidate in enhancing the performance of BiVO4 for PEC solar water splitting applications

Fabrication of exfoliated graphitic carbon nitride, (g-C<inf>3</inf>N<inf>4</inf>) thin film by methanolic dispersion

This paper reports the successful exfoliation of nanosheets from bulk g-C N by using urea as a precursor. The alteration from bulk g-C N powder, changed its semiconductor arrangements such as the optical absorption, chemical bonding, and topography images. A slow direct low thermal treatment (∼40 °C, 24 h) was proposed as a formation of a thinner layer by layer, complete and effective polymerization for an exfoliated g-C N . The photocurrent responses were more than two times higher for exfoliated g-C N compared with bulk g-C N , reaching ∼4.37 μA cm up to 10.21 μA cm at 1.23 vs. (Ag/AgCl). This fabrication method involved dispersing of the highly stable g-C N suspension onto FTO surface via spin coating, followed by a moderate post-annealing temperature at 350 °C. The monolayer g-C N act as a photoelectrode, responding to light and dark current, and maintained its own intrinsic n-types properties. The interaction of the C and N atom with molecules of methanol (CH OH) followed with vibration force (ultrasonication) produces the ultrafast drying and can transmit to disrupt the van der Waals forces within the g-C N structure. Therefore, due to the ability the good performance, the exfoliated g-C N can be envisioned as a potential application such as water splitting, solar cell, and environmental remediation. 3 4 3 4 3 4 3 4 3 4 3 4 3 4 3 3 4 3 4 −2 −