Abstract: A bismuth molybdate gas sensor which provides stable sensitivity to gases such as alcohol, ketones, alkenes, and long chain alkanes is disclosed. Sensors comprising a mixture of the Bi.sub.2 Mo.sub.3 O.sub.12 and Bi.sub.2 MoO.sub.6 phases of bismuth molybdate; or, bismuth iron molybdate are particularly effective. The bismuth molybdate mixture; or, the bismuth iron molybdate may be deposited as a thin film on a substrate or may take the form of a sintered powder.

Abstract: Compositions of the formula MX.sub.2 :Y, wherein MX.sub.2 is a layer type transition metal dichalcogenide, M is a metal selected from the group consisting of niobium, tantalum, molybdenum and tungsten, X is a chalcogen selected from the group consisting of sulfur and selenium and Y is a material located between layers of MX.sub.2. The compositions may be prepared by the steps of first forming a suspension of the MX.sub.2 in a body of water. A liquid which is immiscible with water is added to the suspension. The suspension and immiscible liquid are agitated together to form a temporary emulsion. The emulsion is allowed to rest until the water and the liquid separate with an interface therebetween. A sheet-like composition of MX.sub.2 :Y forms at the interface. Preferably, the MX.sub.2 is in exfoliated, singular molecular thickness layers suspended in the water.

Abstract: A novel flocculated methanation, hydrogenation or hydrodesulfurization catalyst of the form MS.sub.2 :Y:Z wherein MS.sub.2 is a single layer transition metal dichalcogenide sulfide, Y is a promoter substance and Z is a support substance, is disclosed.

Abstract: Novel single layer materials of the form MX.sub.2, where MX.sub.2 is a layer-type dichalcogenide such as MoS.sub.2, TaS.sub.2, WS.sub.2, or the like, exfoliated by intercalation of an alkali metal, and immersion in water, are disclosed. MoS.sub.2 has been exfoliated into monolayers by intercalation with lithium followed by reaction with water. X-ray diffraction analysis demonstrates that the exfoliated MoS.sub.2 in suspension is in the form of one-molecule-thick sheets. X-ray patterns from dried and re-stacked films of exfoliated MoS.sub.2 indicate that the layers are randomly stacked. By adsorbing monolayers or precipitating clusters of various species such as compounds of Co, Ni, Pb, Cd, Al, Ce, In and Zn, on MoS.sub.2 while the sulfide is suspended as single layers and then recrystallizing, a new group of inclusion compounds can be formed. In the re-crystallized or re-stacked materials, the inter-layer spacing can be expanded or contracted compared to MoS.sub.2.