▎ 摘　　要

NOVELTY - Preparing bismuth ferrite-oxidized graphene composite material comprises e.g. mixing graphite powder, sodium nitrate and potassium permanganate, adding graphite powder and sodium nitrate into beaker, adding concentrated sulfuric acid in beaker, adding graphite powder, adding potassium permanganate, subjecting to ice bath treatment, adding deionized water, adding initial graphite powder, then adding initial graphite powder into initial graphite powder, centrifuging at a speed of 2000 revolution/minute, dissolving bismuth(III) nitrate pentahydrate and iron(III) nitrate nonahydrate in deionized. USE - The method is useful for preparing bismuth ferrite-oxidized graphene composite material (claimed). ADVANTAGE - The method reduces recombination probability, improves light catalytic activity, photovoltaic conversion efficiency and photo-catalytic activity. DETAILED DESCRIPTION - Preparing bismuth ferrite-oxidized graphene composite material comprises (i) mixing graphite powder, sodium nitrate and potassium permanganate in a mass ratio of 2:1:4, adding graphite powder and sodium nitrate into beaker, adding concentrated sulfuric acid in beaker, adding 15-20 times (parts by mass) graphite powder of sum of sodium nitrate, ice bath treatment at 5 degrees C for 15-30 minutes, adding 1/3 of potassium permanganate, reacting at 5-10 degrees C for 90 minutes at low temperature, reacting at 35-40 degrees C for medium temperature for 30 minutes, subjecting to ice bath treatment at 5 degrees C for 20 minutes, adding deionized water at room temperature under ice bath process, adding 20-30 times (parts by mass) of initial graphite powder, then adding 10-15 times (parts by mass) of deionized water and 1-2 times (parts by mass) of hydrogen peroxide of initial graphite powder into initial graphite powder, reacting at 80-90 degrees C for 30 minutes at high temperature, centrifuging at a speed of 2000 revolution/minute for 10 minutes, co-centrifuging for 6 times, then solution becomes viscous, increasing centrifugal speed to 8000 revolution/minute for 10 minutes, co-centrifuging for 3 times, again increasing centrifugal speed to 10000 revolution/minute for 10 minutes, carrying centrifugal treatment once after ultrasonification, and again centrifuging at a speed of 4000 revolution/minute for 10 minutes, co-processing for 2 times to obtain enriched graphene solution, (ii) dissolving bismuth(III) nitrate pentahydrate and iron(III) nitrate nonahydrate in deionized water in a molar ratio of 1:1:50, stirring until crystals to dissolve, then preparing 2 mol/l sodium hydroxide solution, adding mixed solution containing bismuth and iron, stirring until pH is greater than 13.5, generating large number of orange precipitation, quickly stirring for 40 minutes to ensure that precipitate is mixed, adding (5-10 vol.% of deionized water) hydrogen peroxide having volume concentration of 30%, placing hot solution into reactor, carrying out hydro thermal reaction at 200 degrees C for 72 hours, centrifuging resulting solution to neutral, and drying in blast oven to obtain bismuth ferrite submicron cubic powder, and (iii) adding 2-4 times (volume ratio) graphene solution obtained in step (i) into water, diluting as dilute solution, adding (400-500 ml of dilute solution) bismuth ferrite powder obtained in step (ii), ultrasonically mixing, transferring resulting mixture into reaction vessel carrying out hydrothermal reaction at 160 degrees C for 6 hours obtaining three-dimensional complex, then dialyzing, placing in freeze dryer, and drying to obtain final product.