Ni@C was prepared according to the method of Liu . Weigh 0.03 mol of Ni (NO3)•6H2O and citric acid and dissolve them in 20 ml of absolute ethanol. The mixture was stirred at 70 ℃ for 8 h and dried at 100 ℃ for 48 h after stirring. The dried green solid was ground into a powder and calcined in an N2 atmosphere for 3 h, the calcining temperature was 700 ℃. The black solid obtained after calcination was washed with1M H2SO4 until it was colorless, and then washed with deionized water until the pH of the waste liquid was 7, and then the solid was freeze-dried at -48 ℃ for 12 h to obtain Ni@C. Place 10ml of tetrabutyl titanate and 10ml of ethanol in the lining of a 100ml polytetrafluororeactor, stir for 5 minutes, add 150 mg of Ni@C and 3 ml of deionized water, and magnetically stir at room temperature for 3 hours. After that, the autoclave reactor (Anhui Kemi Machinery Technology Co., Ltd, Anhui, China) was heated at 150°C for 12 hours. When it was cooled to room temperature washed and filtered.