▎ 摘　　要

NOVELTY - Preparing titanium-MXene-derived sodium titanium phosphate/graphene composite material involves: (1) mixing titanium carbide compound (I) and graphene in a mass ratio of 4:1 to form a stable solution (A); (2) adding 200 mu l hydrogen peroxide, 2 ml phosphoric acid and 100 mg sodium acetate to solution (A) under stirring conditions to obtain a solution (B); (3) adding the solution (B) to a hydrothermal kettle, heating at 160 degrees C for 5 hours, washing the resulting product with deionized water and ethanol, and drying in a vacuum drying oven; and (4) annealing the sample at 700 degrees C for 2 hours in an argon atmosphere. USE - The method is useful for preparing titanium-MXene-derived sodium titanium phosphate/graphene composite material used in hybrid capacitive deionization technology (all claimed). ADVANTAGE - The method is simple in operation and environmentally-friendly, does not use other chemical substances, realizes the material cyclic adsorption and desorption of chloride ions and sodium ions by controlling the size of the applied voltage and adjusting anode and cathode electrodes, and provides composite material, which has sodium chloride adsorption capacity of 251.55 mg/g, and low energy consumption of 0.19 kWhour/kg when used in hybrid capacitance deionized device with activated carbon electrode. DETAILED DESCRIPTION - Preparing titanium-MXene-derived sodium titanium phosphate/graphene composite material involves: (1) mixing a titanium carbide compound of formula: Ti3C2Tx (I) and graphene in a mass ratio of 4:1 to form a stable solution (A); (2) adding 200 mu l hydrogen peroxide, 2 ml phosphoric acid and 100 mg sodium acetate to solution (A) under stirring conditions to obtain a solution (B); (3) adding the solution (B) to a hydrothermal kettle, heating at 160 degrees C for 5 hours, washing the resulting product with deionized water and ethanol, and drying in a vacuum drying oven; and (4) annealing the sample at 700 degrees C for 2 hours in an argon atmosphere. INDEPENDENT CLAIMS are included for the following: (1) the titanium-MXene-derived sodium titanium phosphate/graphene composite material having micron size; and (2) use of the titanium-MXene-derived sodium titanium phosphate/graphene composite material in hybrid capacitive deionization technology, which involves preparing titanium-MXene-derived sodium titanium phosphate/graphene composite electrode and activated carbon electrode by (1) grinding the prepared titanium-MXene-derived sodium titanium phosphate/graphene composite material, mixing with polyvinylidene fluoride (PVDF) and acetylene black according to the mass ratio of 8:1:1, adding N-methylpyrrolidone, stirring for 6-12 hours to obtain a mixed slurry, spreading the slurry on a graphite paper collector, and vacuum drying at 60 degrees C to obtain titanium-MXene-derived sodium titanium phosphate/graphene composite electrode, (2) mixing activated carbon with PVDF and acetylene black for 6-12 hours to obtain a mixed slurry, spreading the slurry on the graphite paper collector, and vacuum drying at 60 degrees C to obtain an activated carbon electrode, (3) assembling a capacitive deionization device by assembling an organic glass water collecting tank, a diaphragm, an anion exchange membrane, the activated carbon electrode, the titanium-MXene-derived sodium titanium phosphate/graphene composite electrode, a collector, and a silica gel gasket in a device for desalting performance testing, where the collection tank is a hollow plate with water inlets and outlets to achieve the purpose of circulating water, (4) after the deionization device is assembled, executing desalination process by adopting a sodium chloride sump, a peristaltic pump, a hybrid capacitor deionization device, and a conductivity meter, where each device is connected with a hose, feeding the sodium chloride brine from the sodium chloride sump to energized hybrid capacitor deionization device by using the peristaltic pump when working, adsorbing, and circulating back to the sodium chloride sump to test the conductivity meter, and (5) realizing the desorption process by reverse connection of the power supply, where the operation is consistent with the adsorption.