Mixed catalyst for fuel cell, method for preparing same, method for forming electrode by using same, and membrane-electrode assembly comprising same

A method of preparing a mixed catalyst for a fuel cell having a target BET surface area, a target micropore surface area, a target external surface area, a target total pore volume, a target micropore volume, and a target mesopore volume, the method comprising:

• a first step of determining a first catalyst including a first support and first catalytic metal particles dispersed on the first support, the first catalyst having a first BET surface area and a first total pore volume;
• a second step of determining a second catalyst including a second support and second catalytic metal particles dispersed on the second support, the second catalyst having a second BET surface area different from the first BET surface area and a second total pore volume different from the first total pore volume;
• a third step of determining a mixing ratio of the first and second catalysts;
• and
• a fourth step of mixing the first catalyst with the second catalyst at the mixing ratio using a resonant acoustic mixer,
• wherein the first and second catalysts are each independently (i) a first-type catalyst having a BET surface area of 150 m2/g or more and a total pore volume of 0.50 cm3/g or more, or (ii) a second-type catalyst having a BET surface area of less than 150 m2/g and a total pore volume of less than 0.50 cm3/g,
• wherein (a) when the first and second catalysts are catalysts of the same type, the first, second and third steps are performed such that the following Equations 13 to 18 are satisfied, and (b) when the first and second catalysts are catalysts of different types, the first, second and third steps are performed such that the following Equations 19 to 24 are satisfied:
• SBET_C1·RC1+SBET_C2·RC2≤TSBET_HC≤(SBET_C1·RC1+SBET_C2·RC2)·1.25 [Equation 13]
• (SMICRO_C1·RC1+SMICRO_C2·RC2)·0.75≤TSMICRO_HC≤SMICRO_C1·RC1+SMICRO_C2·RC2 [Equation 14]
• SEX_C1·RC1+SEX_C2·RC2≤TSEX_HC≤(SEX_C1·RC1+SEX_C2·RC2)·1.25 [Equation 15]
• VT_C1·RC1+VT_C2·RC2≤TVT_HC≤(VT_C1·RC1+VT_C2·RC2)·1.15 [Equation 16]
• (VMICRO_C1·RC1+VMICRO_C2·RC2)·0.85≤TVMICRO_HC≤VMICRO_C1·RC1+VMICRO_C2·RC2 [Equation 17]
• VMESO_C1·RC1+VMESO_C2·RC2≤TVMESO_HC≤(VMESO_C1·RC1+VMESO_C2·RC2)·1.15 [Equation 18]
• (SBET_C1·RC1+SBET_C2·RC2)·0.75≤TSBET_HC≤(SBET_C1·RC1+SBET_C2·RC2)·1.25 [Equation 19]
• (SMICRO_C1·RC1+SMICRO_C2·RC2)·0.75≤TSMICRO_HC≤(SMICRO_C1·RC1+SMICRO_C2·RC2)·1.25 [Equation 20]
• (SEX_C1·RC1+SEX_C2·RC2)·0.75≤TSEX_HC≤(SEX_C1·RC1+SEX_C2·RC2)·1.25 [Equation 21]
• (VT_C1·RC1+VT_C2·RC2)·0.85≤TVT_HC≤(VT_C1·RC1+VT_C2·RC2)·1.15 [Equation 22]
• (VMICRO_C1·RC1+VMICRO_C2·RC2)·0.85≤TVMICRO_HC≤(VMICRO_C1·RC1+VMICRO_C2·RC2)·1.15 [Equation 23]
• (VMESO_C1·RC1+VMESO_C2·RC2)·0.85≤TVMESO_HC≤(VMESO_C1·RC1+VMESO_C2·RC2)·1.15 [Equation 24]
• wherein TSBET_HC is the target BET surface area,
• SBET_C1 is the first BET surface area,
• SBET_C2 is the second BET surface area,
• RC1 is a ratio of a weight of the first catalyst to a weight of the mixed catalyst,
• RC2 is a ratio of a weight of the second catalyst to the weight of the mixed catalyst (i.e., RC2=1−RC1),
• TSMICRO_HC is the target micropore surface area,
• SMICRO_C1 is a micropore surface area of the first catalyst,
• SMICRO_C2 is a micropore surface area of the second catalyst,
• TSEX_HC is the target external surface area,
• SEX_C1 is an external surface area of the first catalyst,
• SEX_C2 is an external surface area of the second catalyst,
• TVT_HC is the target total pore volume,
• VT_C1 is the first total pore volume,
• VT_C2 is the second total pore volume,
• TVMICRO_HC is the target micropore volume,
• VMICRO_C1 is a micropore volume of the first catalyst,
• VMICRO_C2 is a micropore volume of the second catalyst,
• TVMESO_HC is the target mesopore volume,
• VMESO_C1 is a mesopore volume of the first catalyst, and
• VMESO_C2 is a mesopore volume of the second catalyst.