To harvest the unique properties offered by 2D HSs, creation of well-defined heterointerfaces on a large scale is a prerequisite, where the chemistry and nature of heterointerfaces define the targeted applications.

Tobacco use is increasing among young people, especially in Gulf nations such as Saudi Arabia. The objectives of this study were to estimate the prevalence and behavioural patterns of tobacco use among undergraduate students at King Saud University, Riyadh, Saudi Arabia during the academic year 2008/09 and investigate factors that influenced their tobacco use. A cross-sectional study was done of a representative sample (n = 6793) of the undergraduate student population using a modified version of the global youth tobacco survey questionnaire. The prevalence of smoking was 14.5% among students, 22.2% and 2.2% among fathers and mothers and 43.1% and 14.8% for male and female siblings; 15.0% reported all or most of their friends smoked. The most important independent predictors of smoking were: friends' smoking (some: OR = 6.7 and all: OR = 54.9), sister's smoking (OR = 2.2), mother's smoking (OR = 2.1), single status (OR = 1.7) and age (OR = 1.18).

2D metal sulphides (MSs) have attracted enormous amounts of attention in developing high‐performance gas sensors. 2D noble metal sulphides and their derivatives, however, have been less studied due to their predominant nonlayered crystal structures for inefficient exfoliation, despite their surface and peculiar optoelectronic properties. Herein, we successfully synthesize 2D palladium sulphate (PdSO4) from palladium sulphide (PdS) bulk crystals by liquid‐phase exfoliation, in which the presence of oxygen species in the exfoliation solvent plays a key role in the sulphate transformation. Ultrathin 2D PdSO4 planar nanosheets, with thicknesses of ≈3 nm and submicrometer lateral dimensions, exhibit a broad absorption across the visible spectrum, a narrow bandgap of ≈1.35 eV, and a nanosecond scaled long exciton lifetime, which are all suitable for the visible‐light‐driven optoelectronic gas sensing applications. The 2D PdSO4‐based sensor demonstrates a reversible, selective, and sensitive response toward ppb‐leveled NO2 gas at blue light irradiation, featuring a response factor of ≈3.28% for 160 ppb NO2, a low limit of detection of 1.84 ppb, and a > 3 times response factor enhancement over other gases. Herein, the possibility of realizing 2D ultrathin noble metal sulphide compounds from their nonlayered crystal structures and strong potentials in developing high‐performance chemical sensors is explored.

Ultrathin transparent conductive oxides (TCOs) are emerging candidates for next-generation transparent electronics. Indium oxide (In2O3) incorporated with post-transition-metal ions (e.g., Sn) has been widely studied due to their excellent optical transparency and electrical conductivity. However, their electron transport properties are deteriorated at the ultrathin two-dimensional (2D) morphology compared to that of intrinsic In2O3. Here, we explore the domain of transition-metal dopants in ultrathin In2O3 with the thicknesses down to the single-unit-cell limit, which is realized in a large area using a low-temperature liquid metal printing technique. Zn dopant is selected as a representative to incorporate into the In2O3 rhombohedral crystal framework, which results in the gradual transition of the host to quasimetallic. While the optical transmittance is maintained above 98%, an electron field-effect mobility of up to 87 cm2 V–1 s–1 and a considerable sub-kΩ–1 cm–1 ranged electrical conductivity are achieved when the Zn doping level is optimized, which are in a combination significantly improved compared to those of reported ultrathin TCOs. This work presents various opportunities for developing high-performance flexible transparent electronics based on emerging ultrathin TCO candidates.