Abstract In recent years, the development of low-cost and flexible optoelectronic devices with minimal chemical usage has attracted increasing attention for sustainable development. This study introduces our development of a flexible visible photodetector based on a nanohybrid of copper oxide nanoflakes (2D-CuO) and reduced graphene oxide thin film (rGO), using just five initial materials. Particularly, the hydrothermal growth of 2D-CuO needs water and Cu salt, and the rGO production uses graphene oxide and hydrazine (reducing vapor). To build a flexible photodetector, instead of metal evaporation, low-power laser sintering can be employed to create electroconductive carbon electrodes from a polyimide substrate...

Abstract While biomass burning (BB) significantly affects air quality in Southeast Asia, its contribution to PM2.5 in Ho Chi Minh City (HCMC), Vietnam’s most populous city, remains poorly understood. This study aimed to identify the major BB sources contributing to PM2.5 in urban HCMC, with particular attention to the potential underestimation caused by chemical degradation of levoglucosan (Lev), a widely used BB tracer. PM2.5 samples were collected from October to December 2021 and analyzed for their chemical composition, including Lev, mannosan (Man), and potassium from BB (KBB+). The average PM2.5 mass concentration was 26.6 ± 8.8 μg m–3 and was...