▎ 摘　　要

NOVELTY - Preparing Chinese hemp straw biomass graphene-based sulfur-doped tin oxide composite gas-sensitive material comprises e.g. (i) crushing hemp straw, washing, drying, then adding into vacuum tube furnace, heating, carbonizing, mixing carbonized hemp straw carbon with potassium hydroxide aqueous solution, heating, stirring, drying, adding alkali-treated hemp straw carbon into vacuum tube furnace, heating, activating, cooling, washing, and drying to obtain hemp straw carbon template, (ii) dissolving stannous chloride dihydrate and sodium citrate in solvent, stirring, mixing hemp straw carbon template with tin precursor solution, transferring into hydrothermal reactor, reacting, washing composite precursor with distilled water and ethanol, drying, and calcining and (iii) placing hemp straw biomass graphene-based tin oxide composite material in vacuum tube furnace, adding sulfur powder, and passing nitrogen, heating, and carrying out constant temperature vulcanization reaction. USE - The Chinese hemp straw biomass graphene-based sulfur-doped tin oxide composite gas-sensitive material is useful for detecting nitrogen dioxide gas (claimed). ADVANTAGE - The material: has excellent gas-sensitive performance; and solves the problems of low sensitivity, slow response rate, poor selectivity and stability of resistance type room temperature nitrogen dioxide gas sensor, and nitrogen dioxide gas sensor including low sensitivity, slow response rate, poor selectivity and stability. DETAILED DESCRIPTION - Preparing Chinese hemp straw biomass graphene-based sulfur-doped tin oxide composite gas-sensitive material comprises (i) crushing hemp straw, washing with deionized water, and drying, then adding washed and dried hemp straw into vacuum tube furnace under the protection of nitrogen atmosphere, heating at 450-550 degrees C at a heating rate of 2-10 degrees C/minute, and carbonizing at a constant temperature for 2-2.5 hours, mixing carbonized hemp straw carbon with potassium hydroxide aqueous solution, then heating at 85-95 degrees C, stirring until water evaporates and drying to obtain hemp straw carbon after alkali treatment, then adding alkali-treated hemp straw carbon into vacuum tube furnace under the protection of nitrogen atmosphere, heating at 650-750 degrees C at a heating rate of 2-10 degrees C/minute, activating at constant temperature for 2-4 hours, then cooling to room temperature, washing with distilled water until pH is neutral, and drying to obtain hemp straw carbon template, (ii) dissolving stannous chloride dihydrate and sodium citrate in solvent, and stirring until the solution becomes clear to obtain tin precursor solution, mixing hemp straw carbon template prepared in step (i) with tin precursor solution, and allowing to stand, then transferring into hydrothermal reactor, reacting at 160-200 degrees C for 7.5-8.5 hours to obtain composite precursor, washing the composite precursor with distilled water and ethanol, drying, and calcining in muffle furnace at high temperature to obtain hemp straw biomass graphene-based tin oxide composite material, where the solvent is mixture of deionized water and absolute ethanol in a volume ratio of 1:1, and (iii) placing hemp straw biomass graphene-based tin oxide composite material prepared in step (ii) in constant temperature zone of vacuum tube furnace, then adding sulfur powder at the front end of constant temperature zone of vacuum tube furnace, and passing nitrogen as carrier gas, heating at vulcanization temperature of 500-700 degrees C, and carrying out constant temperature vulcanization reaction for 1-2 hours to obtain final product.