Recent advancements in strategies to improve performance of tungsten-based semiconductors for photocatalytic hydrogen production: a review

Multiple efforts have been made to find and utilize sustainable renewable energy to replace fossil fuels that have polluted the environment. Among many semiconductors, tungsten trioxide (WO3) is a promising semiconductor due to its narrow band gap (between 2.5 and 3 eV) and has stable chemical and physical properties. WO3 can absorb a broad range of the solar light spectrum but it is unable to produce hydrogen from water due to its lower conduction band position. However, the high oxidation power of the valence band; nontoxicity and resiliency towards harsh environments such as continuous contact to water and solar irradiation makes it a very promising photocatalyst. The current review article is a literature review on the basis of keywords including hydrogen production; tungsten-based semiconductors; heterojunction formation; band gap engineering, thermodynamics and visible light active photocatalysts. This review aims to summarize the current progress in WO3 based materials for photocatalytic H2 production along with the recent strategies employed for modifications of WO3 based materials for efficient photoactivity. Conventionally, the fundamentals along with the thermodynamics for photocatalytic hydrogen production based on heterogeneous photocatalysts have been discovered. The structural modifications of WO3 with band gap engineering for efficiency enhancement are systematically presented. Recent approaches such as coupling of semiconductors, band gap engineering, establishment of heterojunctions, Z-scheme and step-scheme development to improve the surface sensitization of a semiconductor have been thoroughly discussed. Co-doping semiconductors have proven to reduce the band gap notably and their outstanding electronic band position for visible light photocatalysis has been identified. Modification, doping or coupling of WO3 with a cocatalyst is necessary to change the band gap position. This review article summarizes progress of modifications of WO3 and discusses the future research direction for designing the most efficient WO3 composite towards hydrogen production

Recent advances in constructing heterojunctions of binary semiconductor photocatalysts for visible light responsive CO2 reduction to energy efficient fuels: A review

Photocatalysis of carbon dioxide by the assistance of solar energy has been one of the most promising approaches to reduce CO2 to renewable fuel. Several methods are pertained to enhance the photocatalytic activity for stimulating CO2 reduction to selective fuels. Even though many researchers have been exploring methods of assembling a suitable semiconductor, practical constraints such as charge carrier recombination and low light utilization limit the photocatalytic activity. In this review, recent advancement in semiconductors and their characteristics toward the photoreduction of CO2 has been comprehensively discussed. The major semiconductors that are discussed and analyzed based on their limitations in this review are TiO2, BiVO4, CdS, g-C3N4, ZnO, and MoS2-based composites. Initially, the fundamentals of heterogeneous photocatalysis such as the possible molecular pathways, product selectivity, and thermodynamics have been deliberated. Advancement in semiconductors in relation to quantum dots, heterojunction, and sacrificial reagent has been systematically analyzed. Doping and co-doping of semiconductors have proven to reduce the band gap notably and its outstanding electronic band position for the visible light photocatalysis has been identified. Furthermore, the developments of cocatalysts such as noble metals and nonmetals to stimulate photocatalysts performance in view of CO2 reduction to value-added products have been disclosed. Specific developments in binary semiconductors through Z-scheme, S-scheme, and ternary heterojunction for charge separation and their characterization has been thoroughly deliberated. In addition, the role of doping, structural defects, as well as sensitization in enhancing the light harvesting abilities of the photocatalyst has been discoursed. The developments in photocatalytic reactors with their characteristics and limitations are also assiduously discussed. Finally, conclusions and future directions for photocatalysis of carbon dioxide toward renewable fuel production have been suggested

COVID-19: psychological effects on a COVID-19 quarantined population in Bangladesh

BACKGROUND: It had been seven months since the first confirmed case (8th March, 2020) of COVID-19 in Bangladesh and people have now got a more complete picture of the extent of the pandemic. Therefore, it is time to evaluate the effects of COVID-19 on mental health. The current population-based study aimed to assess the prevalence of depression and PTSD of the quarantined people in Bangladesh during COVID-19 outbreak. METHODS: A total of 5792 individuals comprised the population of this study. Subjects were respondents to an online questionnaire that was administered through social media. The questionnaire included questions on personal information, quarantine related knowledge, items of the Impact of Event Scale-Revised (IES-R) and the Center for Epidemiologic Studies–Depression (CES-D) scale. Data were collected and analyzed by regression utilizing a using IBM SPSS-22 (Statistical Package for Social Science, Chicago, IL, USA). RESULTS: The most post-traumatic stress disorder (PTSD) symptoms had on the male (n = 1392, 75.7%) who had institutional quarantine. The most depression symptoms were on the female (n = 920, 72.8%) whose income was more than 75000 takas in Bangladeshi currency. 81.8% of respondents had PTSD and their scores ≥24 in the IES-R scale. On the other hand, the respondent's income was 40000–74999 takas in Bangladesh currency had more PTSD symptoms and the odd ratio 19.3 (95% CI: 12.5–27.3), adjusted odds ratio 22.9 (95% CI: 15.6–32.4), after adjusting all personal variables. 85.9% respondents scored 16 ≤ in the CES-D scale, meaning they were depressed. The respondents whose education level grade 10 were most depressed and the odd ratio of 3.8 (95% CI: 3.1–4.65), adjusted odds ratio of 13.19 (95% CI: 9.88–17.62) after adjusting all personal variables. CONCLUSIONS: The prevalence of depression and PTSD of the quarantined people higher than that of the affected group during the outbreak of COVID-19 in Bangladesh. If the administration and health care workers become conscious of such results, actions and policies can be taken to improve the consequential sufferings

Assessment of the association between health problems and cooking fuel type, and barriers towards clean cooking among rural household people in Bangladesh

Abstract Background In low- and middle-income countries, households mainly use solid fuels like wood, charcoal, dung, agricultural residues, and coal for cooking. This poses significant public health concerns due to the emission of harmful particles and gases. To address these issues and support Sustainable Development Goals (SDGs), adopting cleaner cooking fuels like electricity and gas are acknowledged as a viable solution. However, access to these cleaner fuels is limited, especially in rural areas. Methods This study conducted a face-to-face survey with 1240 individuals in rural Bangladesh to explore the link between health issues and cooking fuel type, as well as barriers to transitioning to clean cooking. Using a convenient sampling technique across four divisions/regions, the survey gathered socio-demographic and health data, along with information on clean cooking barriers through a semi-structured questionnaire. Binary and multivariable logistic regression analyses were then employed to identify significant associations between cooking fuel type and health problems. Results The study revealed that a majority of participants (73.3%) relied on solid fuel for cooking. The use of solid fuel was significantly correlated with factors such as lower education levels, reduced family income, location of residence, and the experience of health issues such as cough, chest pressure while breathing, eye discomfort, diabetes, asthma, and allergies. Economic challenges emerged as the foremost obstacle to the adoption of clean cooking, accompanied by other contributing factors. Conclusion The use of solid fuel in rural Bangladeshi households poses substantial health risks, correlating with respiratory, eye, cardiovascular, and metabolic issues. Lower education and income levels, along with specific residential locations, were associated with higher solid fuel usage. Economic challenges emerged as the primary obstacle to adopting clean cooking practices. These findings emphasize the need for implementing strategies to promote clean cooking, address barriers, and contribute to achieving Sustainable Development Goal targets for health and sustainable energy access in Bangladesh