| In the paper,two effective electrolyte,namely borate solution(pH=5.1)and carbonate solution(pH=8.3)that is composed of dilute NaOH solution and continuous CO2 gas.The Co-BAi(BAi represents inorganic boric acid)and Mn-BAi oxygen evolution catalyst were generated in situ in H3BO3 solution with Co2+ and Mn2+,respectively.The Co-Ci(Ci represents inorganic carbonate)oxygen evolution catalyst and Ni-Ci oxygen evolution catalyst were generated in situ in carbonate solution with Co2+ and Ni2+m respectively.WO3 electrode materials was coupled with Ni-Bi(Bi represents inorganic borate)oxygen-evolution catalyst to form WO3/Ni-Bi catalyst.The main contents and conclusions are as follows:(1)The Co-BA,oxygen evolution catalyst was generated in situ by controlling constant potential in 0.1 mol/L H3BO3 solution with lmmol/L Co2+under mild condition(45℃,atmospheric pressure,near-neutral solution).The average oxygen evolution rate was 3.13×10-1μmol/h,which increased about 70 times than 4.55×10-3μmol/h of 0.1mol/L H3B03.The Mn-BAi oxygen evolution catalyst was generated in situ by controlling constant potential in 0.1 mol/L H3BO3 solution with lmmol/L Mn2+ under mild condition(25 ℃,atmospheric pressure,near-neutral solution).The average oxygen evolution rate was 1.13μmol/h,which increased about 250 times than 4.55×10-3 μmol/h of 0.1mol/L H3BO3 without Mn2.The results indicated weak acid environment can meet the requirement of electrolyte for preparating oxygen evolution catalyst.(2)Under mild conditions(room temperature,atmospheric pressure,near-neutral solution)Co-Ci oxygen evolution catalyst and Ni-Ci oxygen evolution catalyst were generated in situ through controlling potential coulometry in carbonate solution(pH=8.3)that is composed of dilute NaOH solution and continuous CO2 gas with Co2+ ion and Ni2+ ion,respectively.The oxygen evolution overpotential required η= 395 mV,η = 443 mV corresponding to the current density of 1mA/cm2 and the average oxygen evolution rate was 24.42 μmol/h,17.33 μmol/h when in above electrolyte with Co2+,Ni2+,respectively.(3)Under mild conditions(room temperature,atmospheric pressure,near-neutral solution)WO3 electrode materials that was gegerated by electrochemical methods,was coupled with Ni-Bi oxygen-evolution catalyst in K2B4O7 solution(pH=9.2)with Ni2+ ion to form WO3/Ni-Bi catalyst.The catalyst has excellent catalytic performance for water spliting.The average oxygen evolution rate was 4.50 pmol/h and the overpotential was 258mV at the current density of 1 mA/cm2. |
